ATMEL ATSHA204-MAH-DA-T Atmel cryptoauthentication Datasheet

Atmel ATSHA204
Atmel CryptoAuthentication
DATASHEET
Features
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Secure authentication and validation device
Integrated capability for both host and client operations
Superior SHA-256 hash algorithm, HMAC option
Best-in-class, 256-bit key length; storage for up to 16 keys
Guaranteed unique 72-bit serial number
Internal, high-quality Random Number Generator (RNG)
4.5-Kbit EEPROM for keys and data
512 OTP (One Time Programmable) bits for fixed information
Multiple I/O options
• High-speed, single-wire interface
• 1MHz I2C interface
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2.0V – 5.5V supply voltage range
1.8V – 5.5V communications
<150nA sleep current
Extended, multi-level hardware security
8-lead SOIC, 8-lead TSSOP, 3-lead SOT23, 8-pad UDFN, and
3-lead Contact packages
Applications
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Figure 1.
Pin Name
Pin Configurations
Function
SDA
Serial Data
SCL
Serial Clock Input
GND
Ground
VCC
Power Supply
Anti-clone protection for accessories, daughter cards, and consumables
Secure boot validation, software anti-piracy
Network and computer access control
Key exchange for encrypted downloads
Authenticated/encrypted communications for control networks
8-lead SOIC
3-lead Contact
1
2
SDA
NC
NC
NC
GND
1
8
VCC
2
7
3
6
4
5
NC
SCL
SDA
NC
NC
NC
GND
1
8
VCC
VCC 8
1 NC
2
7
6
4
5
NC 7
SCL 6
SDA 5
2 NC
3
NC
SCL
SDA
GND
VCC
GND
3 NC
4 GND
Bottom View
3-lead SOT23
3
8-lead UDFN
8-lead TSSOP
2
VCC
1
SDA
3
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1.
Introduction
The following sections introduce the features and functions of the Atmel® ATSHA204 authentication device.
1.1
Applications
The ATSHA204 is a member of the Atmel CryptoAuthentication™ family of high-security hardware authentication devices. It
has a flexible command set that allows use for many applications, including the following:
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1.2
Anti-counterfeiting
Validate that a removable, replaceable, or consumable client is authentic. Example clients could be printer ink tanks,
electronic daughter cards, or other spare parts. It can also be used to validate a software/firmware module or
memory storage element.
Protection for Firmware or Media
Validate code stored in flash memory at boot to prevent unauthorized modifications (aka secure boot), encrypt
downloaded media files, and uniquely encrypt code images to be usable on a single system only.
Session Key Exchange
Securely and easily exchange stream encryption keys for use by an encryption/decryption engine in the system
microprocessor to manage such things as a confidential communications channel or an encrypted download.
Secure Data Storage
Store secret keys for use by crypto accelerators in standard microprocessors. It can also be used to store small
quantities of data necessary for configuration, calibration, ePurse value, consumption data, or other secrets.
Programmable protection up through encrypted/authenticated reads and writes.
User Password Checking
Validate user entered passwords without letting the expected value become known, map simple passwords to
complex ones, and securely exchange password values with remote system.
Device Features
The ATSHA204 includes an Electrically Erasable Programmable Read-only Memory (EEPROM) array that can be used for
storage of keys, miscellaneous read/write, read-only or secret data, consumption logging, and security configuration. Access
to the various sections of memory can be restricted in a variety of ways and the configuration then locked to prevent changes.
See Section 2.1, “EEPROM Organization,” for more details on the EEPROM organization.
The ATSHA204 features a wide array of defensive mechanisms specifically designed to prevent physical attacks on the device
itself or logical attacks on the data transmitted between the device and the system (See Section 3.4, “Security Features,” for
more details). Hardware restrictions on the ways in which keys are used or generated, described in Section 3.3, “Key Values,”
provide further defense against certain styles of attack.
Access to the device is through a standard I2C interface at speeds up to 1Mbit/sec (See Section 6 for details on this interface).
It is compatible with standard serial EEPROM I2C interface specifications. The device also supports a single-wire interface that
can reduce the number of GPIOs required on the system processor and/or reduce the number of pins on connectors. The
single-wire interface is described in more detail in Section 5, “Single-wire Interface.”
Using either the I2C or single-wire interface, multiple ATSHA204 devices can share the same bus, which saves processor
GPIO usage in systems with multiple clients such as different color ink tanks or multiple spare parts. See Section 4.2, “Sharing
the Interface,” and Section 8.10, “Pause Command,” for more details on the way in which this is implemented.
Each ATSHA204 ships with a guaranteed unique 72-bit serial number. Using the cryptographic protocols supported by the
device, a host system or remote server can prove that the serial number is both authentic and not a copy. Serial numbers are
often stored in a standard serial EEPROM, but these can be easily copied, and there is no way for the host to know if the serial
number is authentic or a clone.
The Atmel ATSHA204 can generate high-quality random numbers and employ them for any purpose, including as part of the
crypto protocols of this device. Because each 256-bit random number is guaranteed to be unique from all numbers ever
generated on this or any other device, their inclusion in the protocol calculation ensures that replay attacks (re-transmitting a
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previously successful transaction) always fail. Further information is found in Section 3.4.2, “Random Number Generator,” and
Section 8.11, “Random Command.”
System integration is eased with a wide supply voltage range (2.0V through 5.5V) and an ultra-low sleep current of <100nA.
Complete DC parameters are found in Section 7, which describes multiple package options, including a tiny SOT23 package
with a footprint of only 2.5mm x 3mm. See Section 11, “Package Drawings,” for more details and ordering codes.
See Section 9, “Compatibility,” for information regarding compatibility with the Atmel AT88SA102S and Atmel AT88SA10HS,
previous members of the Atmel CryptoAuthentication family.
1.3
Cryptographic Operation
The ATSHA204 supports a standard challenge-response protocol to simplify programming. At its most basic, the host system
sends a challenge to the device in the client, which combines that challenge with a secret key via the MAC command from the
system, described in Section 8.8, “MAC Command,” and sends the response back to the system. The device uses a
cryptographic hash algorithm for the combination, which prevents an observer on the bus from deriving the value of the secret
key, but allows the recipient to verify that the response is correct by performing the same calculation (combining the challenge
with the secret) with a stored copy of the secret.
Due to the flexible command set of the ATSHA204, however, this basic operation can be expanded in many ways. Using the
GenDig command (Section 8.5, “GenDig Command”) the values in other slots can be included in the response digest, which
provides an effective way of proving that a data read really did come from the device, as opposed to being inserted by a manin-the-middle attacker. This same command can be used to combine two keys with the challenge, which is useful when there
are multiple layers of authentication to be performed.
The DeriveKey command (Section 8.3, “DeriveKey Command”) implements a key rolling scheme. Depending on the command
mode parameter, the resulting operation can be similar to that implemented in a remote-controlled garage door opener. Each
time the key is used, the current value of the key is cryptographically combined with a value specific to that system, and the
result forms the key for the next cryptographic operation. Even if an attacker gets the value of one key, that key will be gone
forever with the next use.
DeriveKey can also be used to generate new random keys that might be valid only for a particular host ID, for a particular time
period, or for some other restricted environment. Each generated key is different from any other key ever generated on any
device. By “activating” a host-client pair in the field in this manner, a clone of a single client would not work on any other host.
In a host-client configuration where the host (for instance, a mobile phone) needs to verify a client (for instance, an OEM
battery), there is a need to store the secret in the host in order to validate the response from the client. The CheckMac
command (Section 8.2, “CheckMac Command”) allows the host device to securely store the client secret and hide the correct
response value from the pins, returning only a yes/no answer to the system.
Where a user-entered password is a requirement, the CheckMac command also provides a way to both verify the password
without exposing it on the communications bus as well as map the password to a stored value that can have much higher
entropy. See Section 3.3.6 for more details.
Finally, the hash combination of a challenge and secret key can be kept on the device and XORed with the contents of a slot
to implement an encrypted read (Section 8.12, “Read Command”) , or it can be XORed with encrypted input data to implement
an encrypted write (Section 8.14, “Write Command”).
Each of these operations can be protected against replay attacks by including a random nonce (Section 8.9, “Nonce
Command,”) in the calculation.
All security functions are implemented using the industry-standard SHA-256 secure hash algorithm, which is part of the latest
set of high-security cryptographic algorithms recommended by various governments and cryptographic experts. Section 3.1,
“SHA-256,” includes a reference to the algorithm details. If desired, the SHA-256 algorithm can also be included in an HMAC
sequence (See Section 3.2, “HMAC/SHA-256,” and Section 8.6, “HMAC Command”). The ATSHA204 employs full-sized,
256-bit secret keys to prevent any kind of exhaustive attack.
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2.
Device Organization
The device contains the following memory blocks:
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2.1
EEPROM
SRAM
EEPROM Organization
The EEPROM contains a total of 5312 bits, and is divided into the following zones:
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Data
A 512-byte (4-Kbit) zone split into 16 general-purpose, read-only, or read/write memory slots of 32 bytes (256 bits)
each that can be used to store keys, calibration data, model number, or other information related to the item to which
the Atmel ATSHA204 device is attached. Each slot may have different access restrictions based on the values
stored in the configuration zone. Within this document the nomenclature slot[yy] indicates the 32-byte value stored in
slot yy of the data zone.
Configuration
An 88-byte (704-bit) zone that contains serial number and other ID information as well as access permission
information for each slot of the data memory. Within this document the nomenclature SN[a:b] indicates a range of
bytes within a field of the configuration section. The 88 bytes are accessible from within a three-block address
space.
OTP (One Time Programmable)
A 64-byte (512-bit) zone which can be used to store read-only data. Prior to locking the OTP zone, the bits may be
freely written using the standard Write command. The OTP zone is accessible from within a two-block address
space. Within this document the nomenclature OTP[bb] indicates a byte within the OTP zone, while OTP[aa:bb]
indicates a range of bytes.
Within this document, the terms “slot” and “block” are used interchangeably to mean a single, 256-bit (32-byte) area of a
particular memory zone. The industry SHA-256 documentation uses the term “block” to indicate a 512-bit section of the
message input. In addition, the I/O section of this document uses the term “block” to indicate a variable-length aggregate
element transferred between the system and the device.
Many sections of this document refer to a keyID, which is equivalent to the slot number for those slots designated to hold key
values. Key #1 (sometimes referred to as key[1]) is stored in Slot[1], and so on. While all 16 slots can potentially hold keys,
those slots for which clear reads are permitted would not normally be used as keys by the crypto commands.
In this specification, the nomenclature mode:b indicates bit b of the parameter mode.
On shipment from Atmel, the EEPROM contains factory test data that can be used for fixed-value board testing. This data
must be overwritten with the desired contents prior to locking the configuration and/or data sections of the device. See the
Atmel website for the document containing the specific shipment values.
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2.1.1
Configuration Zone
The 88 bytes in the configuration zone contain manufacturing identification data, general device and system configuration, and
access restriction control values for the slots within the data zone. The values of these bytes can always be obtained using the
Read command. The bytes of this zone are arranged as shown in Table 2-1.
Table 2-1.
Configuration Zone
Byte #
Name
Description
Write
Read
03
SN[0:3]
Part of the serial number value
Never
Always
Never
Always
Never
Always
See the Section 2.1.1.2, “Special Memory Values in the Config Zone (Bytes 0
– 12)”
47
RevNum
Device revision number
See the Section 2.1.1.2, “Special Memory Values in the Config Zone (Bytes 0
– 12)”
8  12
SN[4:8]
Part of the serial number value
See the Section 2.1.1.2, “Special Memory Values in the Config Zone (Bytes 0
– 12)”
13
14
Reserved
Set by Atmel
Never
Always
I2C_Enable
Bit 0:
Never
Always
Never
Always
If config
unlocked
Always
0 = the device operates in single-wire interface mode
2
1 = the device operates in I C interface mode
Bits 1-7 are ignored:
These bits are set at the Atmel factory, depending on the part number, and
cannot be changed.
15
Reserved
Set by Atmel
16
I2C_Address
Bit 0: Ignored
2
Bits 1-7: For I C interface parts, the most-significant seven bits of this byte
form the device address value to which this device will respond. Bits 1, 2, and
4-7 are ignored for single-wire interface parts.
Bit 3 (TTLenable):
1 = the input levels are VCC referenced
0 = the input levels use a fixed reference
See Section 7.4.1 for more information.
2
For devices in which the I C interface is enabled this byte has a default value
of 0xC9 on shipment from Atmel.
17
RFU
Reserved for future use, must be written to 0x00.
If config
unlocked
Always
18
OTPmode
0xAA (Read-only mode) = Writes to the OTP zone are forbidden when the
OTP zone is locked. Reads of all words are permitted.
If config
unlocked
Always
If config
unlocked
Always
If config
unlocked
Always
0x55 (Consumption mode) = Not supported at this time
Contact Atmel for more information.
0x00 (Legacy mode) = When the OTP zone is locked, writes to the OTP zone,
reads of words 0 and 1, and 32-byte reads are all forbidden. See Section 9 for
more information on compatibility with the Atmel AT88SA102S device.
All other values of OTP mode are reserved and should not be used.
19
SelectorMode
If 0, then Selector can always be written with UpdateExtra.
If non-zero, Selector can only be written if it currently has a value of zero.
See Section 8.13 for more details.
20  51
SlotConfig
Two bytes of access and usage permissions and controls for each slot of the
data zone. See the SlotConfig (Bytes 20 – 51) section below for more details.
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Byte #
Name
Description
Write
Read
52,54,56,58
60,62,64,66
UseFlag
For “single use” keys (Section 3.3), this byte indicates how many times a key
may be used before such use is disabled. Applies to keys #0-7 only (byte 52
corresponds to Key0, 54 to Key1, and so on). Initialized to 0xFF.
If config
unlocked
Always
If config
unlocked
Always
If config
unlocked
Always
See Section 3.3.
53,55,57,59
61,63,65,67
UpdateCount
For keys that can be updated with DeriveKey, these bytes indicate how many
times this operation has been performed. Applies to keys #0-7 only, (byte 53
corresponds to Key0, 55 to Key1, and so on).
Initialized to 0x00.
See Sections 3.3 and 8.2.
68  83
LastKeyUse
128 bits to control limited use for KeyID 15.
Initialized to 0xFF.
See Section 3.3.
84
UserExtra
1-byte value that can be modified via the UpdateExtra command after the
data zone has been locked.
Via
update
extra
cmd only
Always
85
Selector
Selects which device will remain in active mode after the execution of the
pause command.
Via
update
extra
cmd only
Always
Via lock
command
only
Always
Via lock
command
only
Always
See Sections 8.10 and 8.13 for more details.
86
LockValue
Controls the ability to write the OTP and data zones.
0x55 = unlocked
0x00 = locked
On shipment from Atmel, this byte has a value of 0x55 corresponding to the
“unlocked” state. After the lock command has been run, this byte will have a
value of 0x00, corresponding to “locked.” See Sections 2.1.2 and 8.7 for more
details.
When locked, the OTP zone can be modified only with the Write command,
and slots in the data zone can be modified only if the corresponding
WriteConfig field so indicates.
When unlocked, the Read command is prohibited within these two zones.
87
LockConfig
Controls the ability to modify the configuration zone.
0x55 = unlocked
0x00 = locked
On shipment from Atmel this byte has a value of 0x55 corresponding to the
“unlocked” state. After the lock command has been run, this byte will have a
value of 0x00, corresponding to”locked.”
See Sections 2.1.2 and 8.7 for more details.
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2.1.1.1 SlotConfig (Bytes 20 – 51)
The 16 SlotConfig elements are used to configure the access protections for each of the 16 slots within the ATSHA204. Each
configuration element consists of 16 bits, which control the usage and access for that particular slot/key. The SlotConfig field is
interpreted according to the following table when the data zone is locked. When the data zone is unlocked, these restrictions
do not apply — all slots may be freely written and none may be read.
Table 2-2.
SlotConfig Bits (per slot)
Bit #
Name
Description
03
ReadKey
Use this keyID to encrypt data being read from this slot using the Read command. If zero,
then this slot can be the source for the CheckMac copy operation (see Section 3.3.6). See
the description for bit 6 in this table, the Read command description in Section 8.12, and
Table 2-3 for more details.
Note: Do not use zero as a default. Do not set this field to zero unless the CheckMac
copy operation is explicitly desired, regardless of any other read/write restrictions.
4
CheckOnly
1 = The key stored in the slot can be used only for CheckMac command. It can also be
used for GenDig if the subsequent use of TempKey is CheckMac. The key cannot be
used by any other command, either directly as KeyID in the input parameter list or via
TempKey.
0 = The key stored in the slot can be used by all crypto commands.
5
SingleUse
1 = The key stored in the slot is “single use.” See Section 3.3 for more details.
Ignored for keys in slots 8-14.
0 = There are no usage limitations.
6
EncryptRead
1 = Reads from this slot will be encrypted using the procedure specified in the Read
command description (Section 8.12) using ReadKey (bits 0 – 3 in this table) to
generate the encryption key. No input MAC is required. If this bit is set, then IsSecret
must also be set (see also Table 2-3).
0 = Clear text reads may be permitted.
7
IsSecret
1 = The contents of this slot are secret: Clear text reads are prohibited, and both 4-byte
reads and writes are prohibited. This bit must be set if EncryptRead is one or if
WriteConfig has any value other than <Always> to ensure proper operation of the
device.
0 = The contents of this slot should not contain confidential data or keys.
See Table 2-3 for additional information.
8  11
WriteKey
Use this key to validate and encrypt data written to this slot.
See Section 8.14 for additional information.
12  15
WriteConfig
Controls the ability to modify the data in this slot.
See Table 2-4 and Section 8.14 for additional information.
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Read operations depend on the state of IsSecret and EncryptRead according to the following table:
Table 2-3.
Read Operation Permission
IsSecret
EncryptRead
Description
0
0
Clear text reads are always permitted from this slot.
Slots set to this state should never be used as key storage.
Either 4 or 32 bytes may be read at a time.
0
1
Prohibited. No security is guaranteed for slots using this code.
1
0
Reads are never permitted from this slot.
Slots set to this state can still be used for key storage.
1
1
Reads from this slot are encrypted using the encryption algorithm documented in the Read
command description (See Section 8.12).
The encryption key is in the slot specified by ReadKey. 4-byte reads and writes are prohibited.
The 4-bit WriteConfig field is interpreted by the Write and DeriveKey commands as shown in Table 2-4 and Table 2-5, where
X means “don’t care.”
Note:
The tables overlap. For example, a code of 0110 indicates a slot that can be written in encrypted form using the
write command and also can be the target of an unauthorized DeriveKey command with the target as the source.
Table 2-4.
Write Configuration Bits – Write Command
Bit 15
Bit 14
Bit 13
Bit 12
Mode Name
0
0
0
X
Always
Clear text writes are always permitted on this slot. Slots set to
“always” should never be used as key storage. Either 4 or 32 bytes
may be written to this slot.
0
0
1
X
Never
Writes are never permitted on this slot using the Write command
Slots set to “never” can still be used as key storage.
1
0
X
X
Never
Writes are never permitted on this slot using the Write command
Slots set to “never” can still be used as key storage.
X
1
X
X
Encrypt
Table 2-5.
Description
Writes to this slot require a properly computed MAC, and the input
data must be encrypted by the system with WriteKey using the
encryption algorithm documented in the Write command description
(Section 8.13). 4-byte writes to this slot are prohibited.
Write Configuration Bits – Derivekey Command
(1)
Bit 15
Bit 14
Bit 13
Bit 12
0
X
1
0
Target
DeriveKey command can be run without authorizing MAC (Roll).
1
X
1
0
Target
Authorizing MAC required for DeriveKey command (Roll).
0
X
1
1
Parent
DeriveKey command can be run without authorizing MAC (Create).
1
X
1
1
Parent
Authorizing MAC required for DeriveKey command (Create).
X
X
0
X
–
Note:
1.
Source Key
Description
Slots with this value in the WriteConfig field may not be used as the
target of the DeriveKey command.
The source key for the computation performed by the DeriveKey command can either be the key directly
specified in Param2 (the “Target”) or the key at slotConfig[Param2].WriteKey (the “Parent”)
See Section 3.3 for more details.
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The IsSecret bit controls internal circuitry necessary for proper security for slots in which reads and/or writes must be
encrypted or are prohibited altogether. It must also be set for all slots that are to be used as keys, including those created or
modified with DeriveKey. Specifically, to enable proper device operation, this bit must be set unless WriteConfig is “always.”
4-byte accesses are prohibited to/from slots in which this bit is set.
Slots used to store key values should always have IsSecret set to one and EncryptRead set to zero (reads prohibited) for
maximum security. For fixed key values, WriteConfig should be set to “never.” When configured in this way, there is no way to
read or write the key after the data zone is locked – it may only be used for crypto operations.
Some security policies require that secrets be updated from time to time. The ATSHA204 supports this capability in the
following way: WriteConfig for the particular slot should be set to “Encrypt” and SlotConfig.WriteKey should point back to the
same slot by setting WriteKey to the slot ID. A standard Write command can be then used to write a new value to this slot
provided that the authentication MAC is computed using the old (current) key value.
2.1.1.2 Special Memory Values in the Config Zone (Bytes 0 – 12)
Various fixed information is included in the ATSHA204 that can never be written under any circumstances and can always be
read, regardless of the state of the lock bits.
•
•
2.1.2
SerialNum
Nine bytes (SN[0:8]) which together form a unique value that is never repeated for any device in the
CryptoAuthentication family. The serial number is divided into two groups:
1. SN[0:1] and SN[8]
The values of these bits are fixed at manufacturing time in most versions of the Atmel ATSHA204. Their
default value is 0x01 23 EE. These 24 bits are always included in the SHA-256 computations made by the
Atmel ATSHA204.
2. SN[2:3] and SN[4:7]
The values of these bits are programmed by Atmel during the manufacturing process and are different for
every die. These 48 bits are optionally included in some SHA-256 computations made by the Atmel
ATSHA204.
RevNum
Four bytes of information that are used by Atmel to provide manufacturing revision information. These bytes can be
freely read as RevNum[0:3], but should never be used by system software, as they may vary from time to time.
Device Locking
There are two separate lock states for the device:
1.
2.
One to lock the configuration zone (controlled by LockConfig, byte 87)
Second to lock both the OTP and data zones (controlled by LockValue, byte 86)
These lock bits are stored within separate bytes in the configuration zone, and can be modified only through the Lock
command. After a memory zone is locked, there is no way to unlock it.
The device should be personalized at the system manufacturer with the desired configuration information, after which the
configuration zone should be locked. When this lock is complete, all necessary writes of public and secret information into the
EEPROM slots should be performed, using encrypted writes if appropriate. Upon completion of any writes, the data and OTP
sections should be locked. Contact Atmel for optional secure personalization services.
It is vital that the data and OTP sections be locked prior to release of the system containing the device into the field. Failure to
lock these zones may permit modification of any secret keys and may lead to other security problems.
Any attempt to read or write the data or OTP sections prior to locking the configuration section causes the device to return an
error.
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2.1.2.1 Configuration Zone Locking
Certain bytes within the configuration zone cannot be modified, regardless of the state of LockConfig. Access to the remainder
of the bytes within the zone is controlled using the LockValue byte in the configuration zone, as shown in the following table.
Throughout this document, if LockConfig is 0x55, the configuration zone is said to be unlocked; otherwise it is locked.
Table 2-6.
Configuration Zone Locking
Read Access
Write Access
LockValue == 0x55 (unlocked)
Read
Write
LockValue != 0x55 (locked)
Read
<never>
2.1.2.2 Data Zone Locking
Throughout this document, if LockValue is 0x55, then both the OTP and data zones are said to be unlocked; otherwise they
are locked.
Note:
There is neither read nor write access to the OTP and data zones prior to locking of the configuration zone.
Table 2-7.
Data zone access restrictions
LockValue == 0x55 (unlocked)
LockValue != 0x55 (locked)
Read Access
Write Access
<never>
Write
Read
Write**
2.1.2.3 OTP Zone Locking
Reads and writes of the OTP zone depend on the state of the LockConfig, LockValue, and OTPmode bytes in the
configuration zone. See Section 2.1.3 for more information.
2.1.3
One Time Programmable (OTP) Zone
This zone of 64 bytes (512 bits) is part of the EEPROM array, and can be used for read-only storage or consumption logging
purposes.
Prior to locking the configuration section (using lockConfig), the OTP zone is inaccessible and can be neither read nor written.
After configuration locking, but prior to locking of the OTP zone (using lockValue), the entire OTP zone can be written using
the Write command. If desired, the data to be written can be encrypted. When unlocked, this zone cannot be read at all.
Once the OTP zone is locked, the OTPmode byte in the configuration zone controls the permissions of this zone, as follows:
•
•
•
Read-only Mode
In this mode, the data cannot be modified, and would be used to store fixed model numbers, calibration information,
manufacturing history, or other data that should never change. The Write command will always return an error and
leave the memory unmodified.
All 64 bytes within the OTP section are always available for reading using either 4- or 32-byte reads.
Consumption Mode
This mode is not currently supported. Contact Atmel for further information.
Legacy Mode
In this mode, the operation of the OTP zone is consistent the fuse array on the Atmel ATSA102S. Reads of words
zero and one are always prohibited, while reads of the remaining 14 words are always permitted. Only 32-bit reads
are permitted, and any attempt to execute a 256-bit read will result in an error return code. All write operations to the
OTP zone are prohibited. See Section 9 or more of the Atmel ATSA102S compatibility details.
All OTP zone bits have a value of one on shipment from the Atmel factory.
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2.2
Static RAM (SRAM)
The device includes an SRAM array that is used to store the input command or output result, intermediate computation values,
and/or an ephemeral key. The entire contents of this memory are always invalidated whenever the device goes into sleep
mode or the power is removed. The ephemeral key is named TempKey, and can be used as an input to the MAC, HMAC,
CheckMac, GenDig, and DeriveKey commands. It is also used as the data protection (encryption or decryption) key by the
Read and Write commands. See below for more details on TempKey.
2.2.1
TempKey
TempKey is a storage register in the SRAM array that can be used to store an ephemeral result value from the Nonce or
GenDig commands. The contents of this register can never be read from the device (although the device itself can read and
use the contents internally).
This register contains the elements shown in Table 2-8.
Table 2-8.
Name
TempKey Storage Register
Length
TempKey
256 bits
(32 bytes)
Description
Nonce (from nonce command) or Digest (from GenDig command)
KeyID
4 bits
If TempKey was generated by GenDig (see the GenData and CheckFlag bits), these bits
indicate which key was used in its computation. The four bits represent one of the slots of
the data zone.
SourceFlag
1 bit
The source of the randomness in TempKey:
0 = Internally generated random number (Rand).
1 = Input seed only, no internal random generation (Input).
GenData
1 bit
0 = TempKey.KeyID is not meaningful, and is ignored.
1 = The contents of TempKey were generated by GenDig using one of the slots in the data
zone (and TempKey.KeyID will be meaningful).
CheckFlag
1 bit
If 1, the contents of TempKey were generated by the GenDig command and at least one of
the keys used in that generation is restricted to the CheckMac command
(SlotConfig.CheckOnly is 1). Otherwise, this bit will be 0.
Valid
1 bit
0 = The information in TempKey is invalid.
1 = The information in TempKey is valid.
In this specification, the name “TempKey” refers to the contents of the 256-bit data register. The remaining bit fields are
referred to as TempKey.SourceFlag, TempKey.GenData, and so on.
The TempKey.Valid bit is cleared to zero under any of the following circumstances:
•
•
•
•
Power up, sleep, brown out, watchdog expiration, or tamper detection. The contents of TempKey, however, are
retained when the device enters idle mode.
After the execution of any command other than Nonce or GenDig, regardless of whether or not the command
execution succeeds. It may be cleared by the CheckMac command unless a successful copy takes place. It is not
cleared if there is a communications problem, as evidenced by a cyclic redundancy check (CRC) error.
An error during the parsing or execution of GenDig and/or Nonce.
Execution of GenDig replaces any previous output of the Nonce command with the output of the GenDig command.
Execution of the Nonce command likewise replaces any previous output of the GenDig command.
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3.
Cryptographic Information
The ATSHA204 implements a challenge-response protocol using either SHA-256 or HMAC/SHA-256, details are below. The
response is always a 256-bit digest.
The Nonce command (see Section 8.9) accepts an input challenge from the system and optionally combines it with an
internally generated random number to generate a nonce (number used once) for the calculation. This seed is then combined
with a secret key as part of the authentication calculation for any of the crypto commands (MAC, HMAC, Read, Write, or
GenDig). For compatibility reasons, the input challenge may be passed directly to the MAC command; however, this operation
is deprecated.
The device can guarantee the uniqueness of the Nonce only if the device has included the output of its random number
generator in the calculation, because the system input may or may not be unique. Every random Nonce is guaranteed to be
unique when compared to all previous nonces, ensuring that each transaction is unique over all time.
3.1
SHA-256
The ATSHA204 MAC command calculates the digest of a secret key concatenated with the challenge or nonce. It optionally
includes various other pieces of information stored on the device within the digested message.
The ATSHA204 computes the SHA-256 digest based on the algorithm documented here:
http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
The complete SHA-256 message processed by the ATSHA204 is listed in Sections 8.5 and 8.9 for each of the particular
commands (GenDig and Nonce) that use the algorithm. Most standard software implementations of the algorithm
automatically add the appropriate number of pad and length bits to this message to match the operation the device performs
internally.
The SHA-256 algorithm is also used for encryption by taking the output digest of the hash algorithm and XORing it with the
plain text data to produce the ciphertext. Decryption is the reverse – the ciphertext is XORed with the digest, and the result is
the plain text.
3.2
HMAC/SHA-256
The response to the challenge can also be computed using the HMAC algorithm based on SHA-256 documented here:
http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
Because of the increased computation complexity, the HMAC command is not as flexible as the MAC command and the
computation time for HMAC is extended. While the HMAC sequence is not necessary to ensure the security of the digest, it is
included for compatibility with various software packages.
3.3
Key Values
All keys within the CryptoAuthentication family are 256 bits long. The ATSHA204 uses these keys as part of the messages
hashed with the MAC, CheckMac, HMAC, and GenDig commands. Any slot in the data zone of the EEPROM can be used to
store a key, though the value will be secret only if the read and write permissions are properly set within SlotConfig (including
the IsSecret bit).
Except for the GenDig command, all but the least-significant four bits of the KeyID parameter are ignored in determining the
source of key data. Only the least-significant four bits are used to select one of the slots of the data zone. See Section 3.3.7,
below, for information on how GenDig uses other KeyID values.
In all cases for which a SHA-256 calculation is performed using Param2, the entire 16-bit KeyID as input is included in the
message.
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3.3.1
Diversified Keys
If the host or validating entity has a place to securely store secrets, the key values stored in the EEPROM slot(s) can be
diversified with the serial number embedded in the device (SN[0:8]). In this manner, every client device can have a unique key,
which can provide extra protection against known plaintext attacks and permit compromised serial numbers to be identified
and blacklisted.
To implement this, a root secret is externally combined with the device serial number during personalization using some
cryptographic algorithm and the result written to the ATSHA204 key slot.
The ATSHA204 CheckMac command provides a mechanism of securely generating and comparing diversified keys,
eliminating this requirement from the host system.
Consult the following application note for more details:
http://www.atmel.com/dyn/resources/prod_documents/doc8666.pdf
3.3.2
Rolled Keys
In order to prevent repeated use of the same key value, the ATSHA204 supports key rolling. Normally, after a certain number
of uses (perhaps as few as one), the current key value is replaced with the SHA-256 digest of its current value combined with
some offset, which may either be a constant, something related to the current system (for example, a serial number or model
number), or a random number.
This capability is implemented using the DeriveKey command. Prior to execution of the DeriveKey command, the Nonce
command must be run to load the offset into TempKey. Each time the roll operation is performed on slots 0-7, the
UpdateCount field for that slot is incremented.
One use for this capability is to permanently remove the original key from the device, replacing it with a key that is only useful
in a particular environment. After the key is rolled, there is no possible way to retrieve the old value, which improves the
security of the system.
Note:
3.3.3
Any power interruption during the execution of the DeriveKey command in Roll mode may cause either the key
or the UpdateCount to have an unknown value. If writing to a slot is enabled using bit number 14 of SlotConfig,
such keys can be written in encrypted and authenticated form using the Write command. Alternatively, multiple
copies of the key can be stored in multiple slots so that failure of a single slot does not incapacitate the system.
Created Keys
In order to support unique ephemeral keys for every client, the ATSHA204 also supports key creation. In this mechanism, a
“parent” key (specified by slotConfig.writeKey) is combined with a fixed or random nonce to create a unique key, which is then
used for any cryptographic purpose.
The ability to create unique keys is especially useful if the parent key has usage restrictions (see “Single-use Keys” and
“Limited-use Key” in the following sections). In this mode, the limited use parent key can be employed to create an unlimited
use child key. Because the child key is useful only for this particular host-client pair, attacks on its value are less valuable.
This capability is also implemented using the DeriveKey command. Prior to execution of the DeriveKey command, the Nonce
command must be run to load the Nonce value into TempKey. Each time the create operation is performed on slots 0-7; the
UpdateCount field for that slot is incremented.
3.3.4
Single-use Keys
For the KeyID values corresponding to slots 0-7 in the data section of the EEPROM, repeated usage of the key stored in the
slot can be strictly limited. This feature is enabled if the SingleUse bit is set in the SlotConfig field. The SingleUse bit is ignored
for slots 8-14. The number of remaining uses is stored as a bit map in the UseFlag byte corresponding to the slot in question.
Prior to execution of any cryptographic command that uses this slot as a key, the following takes place:
•
•
If SlotConfig[keyId].SingleUse is set and UseFlag[KeyID] is 0x00, the device returns an error.
Starting at bit seven of UseFlag[keyID], clear to zero the first bit that is currently a one.
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In practice, this procedure permits SingleUse keys to be used eight times between “refreshes” using the DeriveKey command.
If power is lost during the execution of any command referencing a key that has this feature enabled, one of the use bits in
UseFlag may still be cleared even though the command did not complete. For this reason, Atmel recommends that the key be
used a single time only, with the other bits providing a safety margin for errors.
Under normal circumstances, all eight UseFlag bytes should be initialized to 0xFF. If it is the intention to permit fewer than
eight uses of a particular key, these bytes should be initialized to 0x7F (seven uses), 0x3F (six uses), 0x1F (five uses), 0x0F
(four uses), 0x07 (three uses), 0x03 (two uses), or 0x01 (one use). Initialization to any other value besides these values or
0xFF is prohibited.
The Read, Write, and DeriveKey commands operate slightly differently:
•
•
3.3.5
Read and Write
These commands ignore the state of the SingleUse bit and the UseFlag byte does not change as a result of their
execution. SingleUse slots in which the UseFlag is exhausted (value of 0x00) can still be read or written (subject to
the appropriate SlotConfig limitations) although the value in the slot cannot ever be used as a key for cryptographic
commands.
If SlotConfig.WriteKey for slot X points back to X, but UseFlag[X] is exhausted, encrypted writes to the slot will
never succeed because the prior GenDig command will have returned an error due to the usage limitation. A similar
situation occurs with reads and ReadKey. Slots used as keys should never have IsSecret set to zero or WriteConfig
set to Always.
DeriveKey
If the parent key is used for either authentication or as the source, then if SingleUse (for the parent) is set and
UseFlag (also for the parent) is 0x00, the DeriveKey command returns an error. The SingleUse and UseFlag bits are
ignored for the target key. When successfully executed, DeriveKey always resets the UseFlag to 0xFF for the target
key – this is the only mechanism to reset the UseFlag bits.
Use of the DeriveKey command is optional – it is legal to be run only if WriteConfig: 13 is set for this slot. In some
situations, it may be advantageous to simply have a key that can be used eight times, in which case the other crypto
commands will clear the bits in UseFlag one at a time until all are cleared, and at which time the key is disabled.
Limited-use Key
If Slot[15].SingleUse is set, usage of key number 15 is limited through a different mechanism than the single-use limitation
described above, which applies only to slots 0-7.
Prior to any use of key 15 by a cryptographic command, the following takes place:
•
•
If all bytes in LastKeyUse are 0x00, return error.
Starting at bit seven of the first byte of LastKeyUse (byte 68 in config zone), clear to zero the first bit that is currently
a zero. If byte 68 is 0x00, check bit seven of byte 69, and so on up through byte 83. Only a single bit is cleared each
time prior to using key 15.
There is no reset mechanism for this limitation – after 128 uses (or the number of one bits set in LastKeyUse on
personalization), key 15 is permanently disabled. This capability is not susceptible to power interruptions – even if the power is
interrupted during execution of the command, only a single bit in LastKeyUse will be unknown; all other bits in LastKeyUse will
be unchanged and the key will remain unchanged.
If fewer than 128 uses are desired for key 15, then some of the bytes within this array should not be initialized to 0xFF. As with
UseFlag, the only legal values for bytes within this field (besides 0xFF) are 0x7F, 0x3F, 0x1F, 0x0F, 0x07, 0x03, 0x01, or
0x00. The total number of bits set to one indicates the number of uses. One example of how to set 16 uses is as follows: 0xFF,
0xFF, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00.
The SingleUse bit is ignored by the Read and Write commands, and lastKeyUse does not change as a result of their
execution. The SingleUse bit is ignored by the copy function of the CheckMac command. The SingleUse bit is honored for the
parent key in the DeriveKey command, but is ignored for the target key.
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3.3.6
Password Checking
Many applications require a user to enter a password to enable features, decrypt stored data, or some other purpose.
Typically, the expected password has to be stored somewhere in memory and is, therefore, subject to discovery. The
ATSHA204 can securely store the expected password and perform a number of useful operations on it. The password is never
passed in the clear to the device, nor can it be read from the device. It is hashed with a random number in the system software
before being passed to the device.
The copy capability of the CheckMac command enables the following types of password checking options:
1.
2.
3.
4.
CheckMac does an internal comparison with the expected password and returns a Boolean to the system to indicate
whether the password was correctly entered or not.
If the device determines that the correct password has been entered, then the value of the password can optionally
be combined with a stored or ephemeral value to create a key that can be used by the system for data protection
purposes.
If the device determines that the correct password has been entered, the device can use this fact to optionally
release a secondary, high entropy secret, which can be used for data protection without risk of any exhaustive
dictionary attack.
If the password has been lost, an entity with knowledge of a parent key value can optionally write a new password
into the slot. Also optionally, the current value can be encrypted with a parent key and read from the device.
Passwords should be stored in even-numbered slots. If the password is to be mapped to a secondary value (use #3 above),
then the target slot containing this value is located in the next higher slot number (the password slot number plus one).
Otherwise, the target slot is the same as the password slot.
ReadKey for the target slot must be set to zero to enable this capability. In order to prevent fraudulent or unintended usage of
this capability, do not set ReadKey for any slot to zero unless this CheckMac/copy capability is specifically required. In
particular, do not assume that other bits in the configuration word for a particular slot override the enablement of this capability
specified by ReadKey = 0.
This capability is enabled only if the mode parameter to CheckMac has a value of 0x01, indicating:
a.
b.
The first 32 bytes of the SHA-256 message are stored in a data slot in the EEPROM (the password).
The second 32 bytes of the SHA-256 message must be a randomly generated nonce in the TempKey register.
If the above conditions are met and the input response matches the internally generated digest, then the contents of the target
key are copied to TempKey. The other TempKey register bits are set as follows:
•
•
•
•
3.3.7
SourceFlag is set to one (not random)
GenData is set to zero (not generate by the GenData command)
CheckFlag is set to zero (TempKey is not restricted to the CheckMac command)
Valid is set to one
Transport Keys
The ATSHA204 device includes an internal hardware array of keys (transport keys) that are intended for secure
personalization prior to locking of the data section. The values of the hardware keys are kept secret, and are made available to
qualified customers upon request to Atmel. These keys can be used with the GenDig command only, and are indicated by a
KeyID value ≥ 0x8000.
This is the intended personalization command flow:
1.
2.
3.
Write intended values to the configuration zone, and then lock the configuration zone.
Write non-secret slots and OTP zone, data should be passed to the device in the clear.
Generate a random personalization key in any one of the secret slots with the following sequence:
a.
Nonce command to generate a random nonce in TempKey
b.
c.
d.
Gendig specifying a transport key ≥ 0x8000
Gendig using the compliance (default) value stored in the slot to be used for personalization
Encrypted Write to that same slot (overwrites the compliance value)
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4.
5.
Use that personalization key to write all the secret slots, ending with the final value of the personalization key slot
itself, using the following sequence repeated as necessary:
a.
Nonce command to generate a random nonce in TempKey
b.
Gendig specifying the personalization key
c.
Encrypted write to the target slot
Lock the data zone
For GenDig and all other commands, KeyID values less than 0x8000 always reference keys that are stored in the data zone of
the EEPROM. In these cases, only the four least-significant bits of KeyID are used to determine the slot number, while the
entire 16-bit KeyID as input is used in any SHA-256 message calculation.
3.4
Security Features
3.4.1
Physical Security
The ATSHA204 incorporates a number of physical security features designed to protect the EEPROM contents from
unauthorized exposure. The security measures include:
•
•
•
•
•
An Active Shield over the part
Internal Memory Encryption
Secure Test Modes
Glitch Protection
Voltage Tamper Detection
Pre-programmed transport keys stored on the ATSHA204 are encrypted in such a way as to make retrieval of their values
using outside analysis very difficult.
Both the logic clock and logic supply voltage are internally generated, preventing any direct attack on these two signals using
the pins of the device.
3.4.2
Random Number Generator (RNG)
The ATSHA204 includes a high-quality random number generator that returns 32 random bytes to the system. The device
combines this generated number with a separate input number to form a nonce that is stored within the device in TempKey
and may be used by subsequent commands.
The system may use this random number generator for any purpose. One common purpose would be as the input challenge
to the MAC command on a separate CryptoAuthentication device. The device provides a special Random command for such
purposes, which does do not affect the internally stored nonce.
To simplify system testing, prior to config locking the random number generator always returns the following value:
ff ff 00 00 ff ff 00 00 …
where ff is the first byte read from the device and the first byte into the SHA message.
To prevent replay attacks on encrypted data that is passed to or from the ATSHA204, the device requires that a new, internally
generated nonce be included as part of the encryption sequence used to protect the data being written or read. To implement
this requirement, the data protection key generated by GenDig and used by the Read or Write command must use the internal
random number generator during the creation of the Nonce.
Random numbers are generated from a combination of the output of a hardware random number generator and an internal
seed value, which is not externally accessible. The internal seed is stored in the EEPROM, and is normally updated once after
every power-up or sleep/wake cycle. After the update, this seed value is retained in registers within the device that are
invalidated if the devicez enters sleep mode or the power is removed.
Because there is an EEPROM endurance specification that limits the number of times the EEPROM seed can be updated, the
host system should manage power cycles to minimize the number of required updates. In certain circumstances, the system
may choose to suppress the EEPROM seed update using the mode parameter to the Nonce and Random commands.
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Because this may affect the security of the system, it should be used with caution. See Section 8.9 and Section 8.11 for more
information about how the EEPROM seed update is controlled.
4.
General I/O Information
Communications with the ATSHA204 are achieved through one of two different protocols, and selected using the part number
that is ordered:
•
Single-wire Interface
This mode uses a single GPIO connection on the system microprocessor connected to SDA on the device. It permits
the fewest number of connector pins to any removable/replaceable entity. The bit rate is up to 26-Kbits/sec.
•
I2C Interface
This mode is compatible with the Atmel AT24C16B Serial EEPROM interface. Two pins, Serial Data (SDA) and
Serial Clock (SCL) are required. The I2C interface supports a bit rate of up to 1Mbit/sec.
The lowest levels of the I/O protocols are described below in Sections 5 and 6. Above the I/O protocol level, however, exactly
the same bytes are transferred to and from the device to implement the cryptographic commands and error codes documented
in Section 8.
Note:
4.1
The device implements a failsafe internal watchdog timer that forces it into a very low power mode after a certain
time interval, regardless of any current activity. System programming must take this into consideration. See
Section 8.1.6 for more details.
Byte and Bit Ordering
CryptoAuthentication uses a common ordering scheme for bytes and also for the way in which numbers and arrays are
represented in this datasheet:
•
•
All multi-byte aggregate elements are treated as arrays of bytes and are processed in the order received or
transmitted with index #0 first.
16-bit (2-byte) integers, typically Param2 appear on the bus least-significant byte first.
In this document, the most-significant bit or nibble of a byte or 16-bit word appears towards the left hand side of the page.
The bit order is different depending on the I/O channel used:
•
•
4.1.1
On the one-wire interface, data is transferred to/from the Atmel ATSHA204 least-significant bit first on the bus.
On the I2C interface, data is transferred to/from the Atmel ATSHA204 most-significant bit first on the bus.
Output Example
The following bytes will be returned in this order on the bus by a 32-byte read of the configuration section with an input
address of 0x0000:
SN[0], SN[1], SN[2], SN[3], RevNum[0], RevNum[1], RevNum[2], RevNum[3], SN[4], SN[5], SN[6], SN[7], SN[8], reserved,
I2C Enable, reserved, I2C_Address, TempOffset, OTPmode, SelectorMode, SlotConfig[0].Read, SlotConfig[0].Write,
SlotConfig[1].Read, SlotConfig[1].Write, SlotConfig[2].Read, SlotConfig[2].Write, SlotConfig[3].Read, SlotConfig[3].Write,
SlotConfig[4].Read, SlotConfig[4].Write, SlotConfig[5].Read, SlotConfig[5].Write
4.1.2
MAC Message Example
The following bytes will be passed to the SHA engine for a MAC command using a mode value of 0x71 and a KeyID of slot x.
In the example below, K[x] indicates the KeyID of slot x in the data zone, with K[0] being the first byte on the bus for a read
from or write to that slot. OTP[0] indicates the first byte on the bus for a read of the OTP zone at address zero, and so on.
K[0], K[1], K[2], K[3] … K[31], TempKey[0], TempKey[1], TempKey[2], TempKey[3] … TempKey[31], Opcode (=0x08),
Mode (=0x71), Param2(LSB = x), Param2(MSB = 0), OTP[0], OTP[1], OTP[2], OTP[3], OTP[4], OTP[5], OTP[6],
OTP[7], OTP[8], OTP[9], OTP[10], SN[8], SN[4], SN[5], SN[6], SN[7], SN[0], SN[1], SN[2], SN[3].
For more details regarding MAC messages, see Section 8.8, “MAC Command.”
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4.2
Sharing the Interface
Multiple CryptoAuthentication devices may share the same interface, as follows:
a.
b.
System issues a Wake token (see Section 5.1) to wake up all devices.
The system issues the Pause command to put all but one of the devices into idle mode. Only the remaining device then
sees any commands the system sends. When the system has completed talking to the one active device, it sends an
idle flag, which the idle devices ignore but which puts the single remaining active device into the idle mode. See Section
8.10, “Pause Command,” for more details.
Steps a and b are repeated for each device on the wire. If the system has completed communications with the final device, it
should wake all the devices up and then put all the devices to sleep to reduce total power consumption.
The device uses the selector byte within the configuration zone to determine which device stays awake – only that device with
a selector value that matches the input parameter of the Pause command stays awake. In order to facilitate late configuration
of systems that use the multi-device sharing mode, the following three update capabilities for the selector byte are supported:
1.
Unlimited Updates
At any time, the UpdateExtra command can be executed to write the value in the selector field of the configuration
zone. To enable this mode, set the SelectorMode byte in the configuration zone to zero.
One-time Field Update
If the SelectorMode byte is set to a non-zero value and the selector byte is set to a zero value prior to locking the
configuration zone, then at any time after the configuration zone is locked the UpdateExtra command can be used
one time to set Selector to a non-zero value. The UpdateExtra command is not affected by the LockValue byte.
Fixed Selector Value
The selector byte can never be modified after the configuration zone is locked if both SelectorMode and Selector are
set to non-zero values. The UpdateExtra command will always return an error code.
2.
3.
5.
Single-wire Interface
In this mode, communications to and from the ATSHA204 take place over SDA, a single, asynchronously timed wire, and the
SCL pin is ignored.
Note:
The sleep current specification values are guaranteed only if the SCL pin is held low or left unconnected.
The overall communications structure is a hierarchy:
Tokens
I/O tokens implement a single data bit transmitted on the bus, or the wake-up event.
Flags
Flags consist of eight tokens (bits) that convey the direction and meaning of the next group of bits (if any)
that may be transmitted.
Blocks
Blocks of data follow the command and transmit flags. They incorporate both a byte count and a checksum
to ensure proper data transmission.
Packets
Packets of bytes form the core of the block (minus the byte count and CRC). They are either the input or
output parameters of a CryptoAuthentication command or status information from the Atmel ATSHA204.
See the Atmel website for the appropriate application notes for more details on how to use any microprocessor to easily
generate the signaling necessary to send these elements to the device, including C source code libraries. Also, see Section
10.2, “Wiring Configuration for Single-wire Interface,” for more information about how to connect the device in the single-wire
interface mode.
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5.1
I/O Tokens
There are a number of I/O tokens that may be transmitted over the single-wire interface:
Input:
(to the Atmel ATSHA204)
Wake
Wake the device up from either sleep or idle states.
Zero
Send a single bit from the system to the device with a value of zero.
One
Send a single bit from the system to the device with a value of one.
Output: (from the Atmel ATSHA204)
ZeroOut
Send a single bit from the device to the system with a value of zero.
OneOut
Send a single bit from the device to the system with a value of one.
The waveforms are the same in either direction. There are some differences in timing, however, based on the expectation that
the host has a very accurate and consistent clock, while the ATSHA204 has significant part-to-part variability in its internal
clock generator, due to normal manufacturing and environmental fluctuations.
The bit timings are designed to permit a standard UART running at 230.4K baud to transmit and receive the tokens efficiently.
Each byte transmitted or received by the UART corresponds to a single bit received or transmitted by the device.
The Wake token is special in that it requires an extra long low pulse on the SDA pin, which cannot be confused with the
shorter low pulses that occur during a data token (Zero, One, ZeroOut, OneOut). Devices that are in either the idle or sleep
state ignore all data tokens until they receive a legal Wake token. Do not send a Wake token to devices that are awake, as
they will lose synchronization because the waveform can be resolved to neither a legal one nor zero. See Section 5.3.2 for the
procedure to regain synchronization.
5.2
I/O Flags
The system is always the bus master, so before any I/O transaction, the system must send an 8-bit flag to the device to
indicate the I/O operation to be subsequently performed, as shown in Table 5-1.
Table 5-1.
I/O flags
Value
Name
Meaning
0x77
Command
After this flag, the system starts sending a command block to the device.
The first bit of the block can follow immediately after the last bit of the flag.
0x88
Transmit
This command tells the device to wait for a bus turnaround time and then start transmitting its
response to the previously transmitted command block.
0xBB
Idle
Upon receipt of an idle flag, the device goes into the idle mode and remains there until the next
wake token is received.
0xCC
Sleep
Upon receipt of a sleep flag, the device enters the low-power sleep mode until the next Wake token
is received.
All other values are reserved and should not be used
5.2.1.1 Transmit Flag
The transmit flag is used to turn the bus around so that the ATSHA204 can send data back to the system. The bytes that the
device returns to the system depend on the current state of the device, and may include either status, error code, or command
results.
When the device is busy executing a command, it ignores the SDA pin and any flags sent by the system. See Table 8-4 for
execution delays in the device for each command type. The system must observe these delays after sending a command to
the device.
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5.2.1.2 Idle Flag
The idle flag is used to transition the ATSHA204 to the idle state, which causes the input/output buffer to be flushed. It does
not invalidate the contents of the TempKey and RNG seed registers. This flag can be sent to the device at any time when it will
accept a flag. When the device is in the idle state, the watchdog timer is disabled.
5.2.1.3 Sleep Flag
The sleep flag transitions the ATSHA204 to the low-power sleep state, which causes a complete reset of the device, including
invalidation of the contents of the SRAM and all volatile registers. This flag can be sent to the device at any time when it will
accept a flag.
5.3
Synchronization
Because the communications protocol is half-duplex, there is the possibility that the system and the ATSHA204 will fall out of
synchronization with each other. In order to speed recovery, the device implements a timeout that forces it to sleep under
certain circumstances.
5.3.1
I/O Timeout
After a leading transition for any data token has been received, the ATSHA204 will expect the remaining bits of the token to be
properly received by the device within the tTIMEOUT interval. Failure to send enough bits or the transmission of an illegal token
(a low pulse exceeding tZLO) will cause the device to enter the sleep state after the tTIMEOUT interval.
The same timeout applies during the transmission of the command block. After the transmission of a legal command flag, the
I/O timeout circuitry is enabled until the last expected data bit is received.
Note:
The timeout counter is reset after every legal token, and so the total time to transmit the command may exceed
the tTIMEOUT interval while the time between bits may not.
The I/O timeout circuitry is disabled when the device is busy executing a command.
5.3.2
Synchronization Procedures
If the device is not busy when the system sends a transmit flag, the device should respond within tTURNAROUND. If tEXEC time has
not already passed, the device may be busy, and the system should poll or wait until the maximum tEXEC time has elapsed. If
the device still does not respond to a second transmit flag within tTURNAROUND, it may be out of synchronization. At this point, the
system may take the following steps to reestablish communication:
1.
2.
3.
4.
5.
6.
7.
Wait tTIMEOUT.
Send the transmit flag.
If the device responds within tTURNAROUND, then the system may proceed with more commands.
Send a Wake token.
Wait tWHI.
Send the transmit flag.
The device should respond with a 0x11 status within tTURNAROUND, at which time system may proceed with
commands.
Any command results in the I/O buffer may be lost when the system and device lose synchronization.
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6.
I2C Interface
The I2C interface uses the SDA and SCL pins to indicate various I/O states to the ATSHA204. This interface is designed to be
compatible at the protocol level with the AT24C16B Serial EEPROM operating at 1MHz.
The SDA pin is normally pulled high with an external pull-up resistor, as the ATSHA204 includes only an open-drain driver on
its output pin. The bus master may be either open–drain or totem pole, and if the latter, then it should be tri-stated when the
ATSHA204 is driving results on the bus. The SCL pin is an input, and must be driven both high and low at all times by an
external device
6.1
I/O Conditions
The device responds to the following I/O conditions:
6.1.1
Device is Asleep
When the device is asleep, it ignores all but the wake condition
Wake:
If SDA is held low for a period greater than tWLO, the device exits low-power mode and, after a delay of tWHI,
is ready to receive I2C commands. The device ignores any levels or transitions on the SCL pin when the
device is idle or asleep and during tWLO. At some point during tWHI, the SCL pin is enabled and the conditions
listed in Section 6.1.2, “Device is Awake,” are honored.
The wake condition requires either that the system processor manually drive the SDA pin low for tWLO, or that a data byte of
0x00 is transmitted at a clock rate sufficiently slow that SDA is low for a minimum period of tWLO. When the device is awake,
the normal processor I2C hardware and/or software can be used for device communications up to and including the I/O
sequence required toput the device back into low power (sleep) mode.
When there are multiple ATSHA204 devices on the bus and the I2C interface is run at 133KHz or slower, the transmission of
certain data patterns (such as 0x00) will cause all the ATSHA204 devices on the bus to wake up. Because subsequent device
addresses transmitted along the bus will only match the desired devices, the unused devices will remain idle and not cause
any bus conflicts.
In I2C mode, the device will ignore a wake sequence sent when the device is already awake.
6.1.2
Device is Awake
When the device is awake, it honors the conditions listed below.
Data Zero:
If SDA is low and stable while SCL goes from low to high to low, then a zero bit is being transferred on the
bus. SDA can change while SCL is low.
Data One:
If SDA is high and stable while SCL goes from low to high to low, then a one bit is being transferred on the
bus. SDA can change while SCL is low.
2
Figure 6-1. Data Bit Transfer on I C Interface
SDA
SCL
Data line stable;
Data valid
Change of
data allowed
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Start:
A high-to-low transition of SDA with SCL high is a start condition, which must precede all commands.
Stop:
A low-to-high transition of SDA with SCL high is a stop condition. After this condition is received by the
device, the current I/O transaction ends. On input, if the device has sufficient bytes to execute a command,
the device transitions to the busy state and begins execution. The stop condition should always be sent after
any packet sent to the device.
2
Figure 6-2. Start and Stop Conditions on I C Interface
SDA
SCL
S
P
Start
Condition
Stop
Condition
Acknowledge (ACK): On the ninth clock cycle after every address or data byte is transferred, the receiver will pull the
SDA pin low to acknowledge proper reception of the byte.
Not Acknowledge (NACK): Alternatively, on the ninth clock cycle after every address or data byte is transferred, the
receiver can leave the SDA pin high to indicate that there was a problem with the reception of the byte or
that this byte completes the block transfer.
2
Figure 6-3. NACK and ACK Conditions on I C Interface
Data Output
by Transmitter
Not Acknowledge
Data Output
by Receiver
Acknowledge
SCL from
Master
1
S
Start
Condition
2
8
9
Clock Pulse for
Acknowledgement
2
Multiple ATSHA204 devices can easily share the same I C interface if the I2C_Device address byte is programmed differently
for each device on the bus. Because six of the bits of the device address are programmable, the ATSHA204 can also share
the I2C interface with any standard I2C device, including any serial EEPROM. Bit 3 (also known as TTL Enable) must be
programmed according the input thresholds desired, and is fixed in a particular application.
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6.2
I2C Transmission to the Atmel ATSHA204 Device
The transmission of data from the system to the AT88SA102S is summarized in Figure 6-4. The order of transmission is:
•
•
•
•
•
Start Condition
Device Address Byte
Word Address Byte
Optional Data Bytes (1 through N)
Stop Condition
Figure 6-4. Normal I2C Transmission to an Atmel ATSHA204
SDA
1-7
SCL
8
9
R/W
ACK1
1-7
8
9
1-7
8
9
1-7
8
9
1-7
8
9
P
S
Device
Start
Condition Address
Note:
Word
Address
ACK1
Data 1
ACK1
Data 2
ACK1
Data N
ACK1
Stop
Condition
SDA is driven low by the Atmel ATSHA204 during the ACK periods
The tables below label the bytes of the I/O transaction. The I2C name column provides the names of the bytes as described in
the AT24C16B datasheet.
Table 6-1.
2
I C Transmission to Atmel ATSHA204
2
Atmel ATSHA204
I C Name
Description
Device Address
Device Address
This byte selects a particular device on the I2C interface. The Atmel ATSHA204 is
selected if bits 1-7 of this byte match bits 1-7 of the I2C_Address byte in the
configuration zone. Bit 0 of this byte is the standard I2C R/W bit, and should be
zero to indicate a write operation (the bytes following the device address travel
from the master to the slave).
Word Address
Word Address
This byte should have a value of 0x03 for normal operation.
See Sections 6.2.2 and 6.6, below, for more information.
Command
Data1-n
The command block, consisting of the count, command packet, and the two-byte
CRC. The CRC is calculated over the size and packet bytes. See Section 8.1.
2
Because the device treats the command input buffer as a FIFO, the input block can be sent to the device in one or many I C
command blocks. The first byte sent to the device is the count, and so after the device receives that number of bytes, it will
ignore any subsequently received bytes until execution is finished.
The system must send a stop condition after the last command byte to ensure that the ATSHA204 will start the computation of
the command. Failure to send a stop condition may eventually result in a loss of synchronization (See Section 6.7 for recovery
procedures).
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6.2.1
Word Address Values
During an I2C write packet, the ATSHA204 interprets the second byte sent as the word address, which indicates the packet
function, as described in the following table.
Table 6-2.
6.2.2
Word Address Values
Name
Value
Description
Reset
0x00
Reset the address counter. The next read or write transaction will start with the
beginning of the I/O buffer.
Sleep
(low power)
0x01
The Atmel ATSHA204 goes into the low-power sleep mode and ignores all subsequent
I/O transitions until the next Wake flag. The entire volatile state of the device is reset.
Idle
0x02
The Atmel ATSHA204 goes into the idle state and ignores all subsequent I/O transitions
until the next Wake flag. The contents of TempKey and RNG seed registers are
retained.
Command
0x03
Write subsequent bytes to sequential addresses in the input command buffer that follow
previous writes. This is the normal operation.
Reserved
0x04 – 0xFF
These addresses should not be sent to the device.
Command Completion Polling
After a complete command has been sent to the ATSHA204, the device will be busy until the command computation
completes. The system has two options for this delay:
•
•
6.3
Polling
The system should wait tEXEC (typical) and then send a read sequence (See Section 6.5). If the device NACKs the
device address, then it is still busy. The system may delay for some time or immediately send another read
sequence, again looping on NACK. After a total delay of tEXEC (max), the device will have completed the computation
and return the results.
Single Delay
The system should wait tEXEC (max), after which the device will have completed execution and the result can be read
from the device using a normal read sequence.
Sleep Sequence
Upon completion of system use of the ATSHA204, the system should issue a sleep sequence to put the device into low-power
mode. This sequence consists of the proper device address followed by the value of 0x01 as the word address followed by a
stop condition. This transition to the low-power state causes a complete reset of the device internal command engine and
input/output buffer. It can be sent to the device at any time when it is awake and not busy.
6.4
Idle Sequence
If the total sequence of required commands exceeds tWATCHDOG, then the device will automatically go to sleep and lose any
information stored in the volatile registers. This action can be prevented by putting the device into the idle state prior to
completion of the watchdog interval. When the device receives the wake token, it will then restart the watchdog timer, and
execution can be continued.
The idle sequence consists of the proper device address followed by the value of 0x02 as the word address followed by a stop
condition. It can be sent to the device at any time when it is awake and not busy.
If TempKey was created as a result of the copy mode of the CheckMac command, it will not be retained when the part goes
into an idle state.
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6.5
I2C Transmission from the Atmel ATSHA204 Device
When the ATSHA204 is awake and not busy, the bus master can retrieve the current buffer contents from the device using an
I2C read. If valid command results are available, the size of the block returned is determined by the particular command that
has been run (See Section 8. “Commands”), otherwise the size of the block (and the first byte returned) will always be four:
count, status/error, and 2-byte CRC. The bus timing is shown in Figure 7-3 in Section 7.3.2.
Table 6-3.
I2C transmission from Atmel ATSHA204
2
Atmel ATSHA204
I C Name
Direction
Description
Device Address
Device Address
To slave
This byte selects a particular device on the I2C interface, and the Atmel
ATSHA204 will be selected if bits 1-7 of this byte match bits 1-7 of the
I2C_Address byte in the configuration zone. Bit 0 of this byte is the
standard I2C R/W pin, and should be one to indicate that the bytes
following the device address travel from the slave to the master (read).
Data
Data1,N
To master
The output block, consisting of the count and status/error byte or the
output packet followed by the two-byte CRC per Section 8.1.
The status, error, or command outputs can be read repeatedly by the master. Each time a read command is sent to the
2
ATSHA204 along the I C interface, the device transmits the next sequential byte in the output buffer. See the following section
for details on how the device handles the address counter.
If the ATSHA204 is busy, idle, or asleep, it will NACK the device address on a read sequence. If a partial command has been
sent to the device, then it will NACK the device address, but float the bus during the data intervals.
6.6
Address Counter
Writes to and/or reads from the ATSHA204 I/O buffer over the I2C interface are treated as if the device were a FIFO. Either the
I2C byte or block write/read protocols can be used. The number of bytes transferred with each block sequence does not affect
the operation of the device.
The first byte transmitted to the device is treated as the size byte. Any attempt to send more than this number of bytes or any
attempts to write beyond the end of the I/O buffer (84 bytes) will cause the ATSHA204 to NACK those bytes.
After the host writes a single command byte to the input buffer, reads from the host are prohibited until after the device
completes command execution. Attempts to read from the device prior to the last command byte being sent will result in an
ACK of the device address but all ones (0xFF) on the bus. If the master attempts to send a read byte to the device during
command execution, the device will NACK the device address.
Data may be read from the device under the following three conditions:
•
•
•
On power up, the single byte, 0x11 (See Section 8.1.3), can be read inside a four byte block.
If a complete block has been received by the device, but there are any errors in parsing or executing the command,
a single byte of error code is available, also inside a four byte block.
Upon completion of command execution, from 1-32 bytes of command result are available to be read inside a block
of 4-35 bytes.
Any attempt to read beyond the end of the valid output buffer returns 0xFF to the system – the address counter does not wrap
around to the beginning of the buffer.
There may be situations where the system may wish to re-read the output buffer; for example, when the CRC check reveals
an error. In this case, the master should send a two-byte sequence to the ATSHA204 consisting of the correct device address
and a word address of 0x00 (Reset, per Table 6-2), followed by a stop condition. This causes the address counter to be reset
to zero, and permits the data to be re-written (re-read) to (from) the device. This address reset sequence does not prohibit
subsequent read operations if data was available for reading in the I/O buffer prior to the sequence execution.
After one or more read operations to retrieve the results of a command execution, the first write operation resets the address
counter to the beginning of the I/O buffer.
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6.7
I2C Synchronization
It is possible for the system to lose synchronization with the I/O port on the ATSHA204, perhaps due a system reset, I/O noise,
or other condition. Under this circumstance, the ATSHA204 may not respond as expected, may be asleep, or may be
transmitting data during an interval when the system is expecting to send data. Any command results in the I/O buffer may be
lost when the system and device lose synchronization.
To re-synchronize, the following procedure should be followed:
1.
2.
3.
To ensure an I/O channel reset, the system should send the standard I2C software reset sequence, as follows:
•
A start condition
•
Nine cycles of SCL with SDA held high
•
Another start condition
•
A stop condition
It should then be possible to send a read sequence, and, if synchronization has completed properly, the ATSHA204
will ACK the device address. The device may return data or may leave the bus floating (which the system will
interpret as a data value of 0xFF) during the data periods.
If the device does ACK the device address, the system should reset the internal address counter to force the
ATSHA204 to ignore any partial input command that may have been sent. This can be accomplished by sending a
write sequence to word address 0x00 (Reset), followed by a stop condition.
If the device does not respond to the device address with an ACK, then it may be asleep. In this case, the system
should send a complete wake token and wait tWHI after the rising edge. The system may then send another read
sequence, and, if synchronization has completed, the device will ACK the device address.
If the device still does not respond to the device address with an ACK, then it may be busy executing a command.
The system should wait the longest tEXEC (max) and then send the read sequence, which will be acknowledged by
the device.
7.
Electrical Characteristics
7.1
Absolute Maximum Ratings*
Operating Temperature ............................... −40°C to +85°C
*Notice:
Storage Temperature................................ −65°C to + 150°C
Maximum Operating Voltage ........................................ 6.0V
DC Output Current ..................................................... 5.0mA
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent
damage to the device. This is a stress rating
only, and functional operation of the device at
these or any other condition beyond those
indicated in the operational sections of this
specification is not implied. Exposure to
absolute maximum rating conditions for
extended periods may affect device reliability.
Voltage on any pin ............................... -0.5V to (VCC + 0.5V)
7.2
Reliability
The ATSHA204 is fabricated with the high reliability of the Atmel CMOS EEPROM manufacturing technology.
Table 7-1.
EEPROM reliability
Parameter
Write Endurance (each byte at 25°C)
Min
Typical
Max
Units
100,000
Write Cycles
Data Retention (at 55°C)
10
Years
Data Retention (at 35°C)
30
Read Endurance
50
Years
Unlimited
Read Cycles
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7.3
AC Parameters – All I/O Interfaces
Figure 7-1. AC Timing Diagram – All I/O Interfaces
Wake
Data Comm
tWLO
tWHI
Noise
Suppression
tLIGNORE
Table 7-2.
tHIGNORE
AC Parameters – All I/O Interfaces
Parameter
Symbol
Direction
Min
Wake Low
Duration
tWLO
To Crypto
Authentication
60
Wake High
Delay to
Data Comm.
tWHI
To Crypto
Authentication
High Side
Glitch Filter
@ Active
tHIGNORE_A
Low Side
Glitch Filter
@ Active
Max
Unit
-
µs
SDA can be stable in either high or low
levels during extended sleep intervals.
2.5
ms
SDA should be stable high for this entire
duration.
To Crypto
Authentication
45(1)
ns
Pulses shorter than this in width will be
ignored by the device, regardless of its
state when active.
tLIGNORE_A
To Crypto
Authentication
45(1)
ns
Pulses shorter than this in width will be
ignored by the device, regardless of its
state when active.
High Side
Glitch Filter
@ Sleep
tHIGNORE_S
To Crypto
Authentication
15(1)
µs
Pulses shorter than this in width will be
ignored by the device when in sleep
mode.
Low Side
Glitch Filter
@ Sleep
tLIGNORE_S
To Crypto
Authentication
15(1)
µs
Pulses shorter than this in width will be
ignored by the device when in sleep
mode.
Watchdog
Reset
tWATCHDOG
To Crypto
Authentication
0.7
s
Max. time from wake until device is
forced into sleep mode (See Section
8.1.6).
Note:
1.
Typ
1.3
1.7
Notes
These parameters are guaranteed through characterization, but not tested.
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7.3.1
AC Parameters – Single-wire Interface
Figure 7-2. AC Timing Diagram – Single-wire Interface
LOGICØ
tSTART
tZHI
tZLO
tBIT
LOGIC 1
tSTART
Table 7-3.
AC Parameters – Single-wire Interface
Applicable from TA = −40°C to +85°C, VCC = +2.0V to +5.5V, CL =100pF (unless otherwise noted)
Parameter
Symbol
Direction
Min
Typ
Max
Unit
Start Pulse
Duration
tSTART
To Crypto
Authentication
4.1
4.34
4.56
µs
From Crypto
Authentication
4.6
6.0
8.6
µs
To Crypto
Authentication
4.1
4.34
4.56
µs
From Crypto
Authentication
4.6
6.0
8.6
µs
To Crypto
Authentication
4.1
4.34
4.56
µs
From Crypto
Authentication
4.6
6.0
8.6
µs
To Crypto
Authentication
37
39
-
µs
From Crypto
Authentication
41
54
78
µs
From Crypto
Authentication
28
60
95
µs
The Atmel ATSHA204 will initiate the first
low-going transition after this time interval
following the end of the last bit (tBIT) of the
Transmit flag.
To Crypto
Authentication
15
µs
After the Atmel ATSHA204 transmits the last
bit of a block, the system must wait this
interval before sending the first bit of a flag.
To Crypto
Authentication
45
ms
The Atmel ATSHA204 may transition to the
sleep state if the bus is inactive longer than
this duration. See Section 5.3.1 for specific
details.
Zero
Transmission
High Pulse
tZHI
Zero
Transmission
Low Pulse
tZLO
Bit Time(1)
tBIT
Turnaround
Delay
I/O Timeout
Note:
1.
tTURNAROUND
tTIMEOUT
65
85
Notes
If the bit time exceeds tTIMEOUT, then the
Atmel ATSHA204 may enter the sleep state.
See Section 5.3.1 for specific details.
tSTART, tZLO, tZHI, and tBIT are designed to be compatible with a standard UART running at 230.4K baud for both
transmit and receive. The UART should be set to seven data bits, no parity, and one stop bit.
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7.3.2
AC Parameters – I2C Interface
Figure 7-3. I2C Synchronous Data Timing
tHIGH
tF
tR
tLOW
SCL
tLOW
tHD.DAT
tHD.STA
tSU.STA
tSU.STO
tSU.DAT
SDA IN
tAA
tDH
tBUF
SDA OUT
Table 7-4.
AC Characteristics of I2C Interface
Applicable over recommended operating range from TA = −40°C to + 85°C, VCC = +2.0V to +5.5V, CL = 1 TTL gate and 100pF
(unless otherwise noted)
Symbol
Parameter
Min
Max
Units
fSCK
SCK Clock Frequency
0
1
MHz
SCK Clock Duty Cycle
30
70
percent
tHIGH
SCK High Time
400
ns
tLOW
SCK Low Time
400
ns
tSU.STA
Start Setup Time
250
ns
tHD.STA
Start Hold Time
250
ns
tSU.STO
Stop Setup Time
250
ns
tSU.DAT
Data in Setup Time
100
ns
tHD.DAT
Data in Hold Time
0
ns
tR
Input rise time (1)
(1)
300
ns
100
ns
550
ns
tF
Input Fall Time
tAA
Clock Low to Data Out Valid
50
tDH
Data Out Hold Time
50
ns
tBUF
Time bus must be free before a new transmission can start. (1)
500
ns
Notes:
1.
Values are based on characterization, but are not tested.
2. AC measurement conditions:



RL (connects between SDA and VCC): 2.0kΩ (for VCC +2.0V to +5.0V)
Input pulse voltages: 0.3VCC to 0.7VCC
Input rise and fall times: ≤ 50ns
Input and output timing reference voltage: 0.5VCC
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7.4
DC Parameters – All I/O Interfaces
Table 7-5.
DC Parameters – All I/O Interfaces
Parameter
Symbol
Min
Typ
Max
Unit
Ambient Operating
Temperature
TA
-40
85
°C
Power Supply
Voltage
VCC
2.0
5.5
V
Active Power
Supply Current
ICC
Idle Power Supply
Current
I IDLE
700
Sleep Current
I SLEEP
30
1
-
3
150
Notes
mA
0°C +70°C, VCC = 3.3V
mA
-40°C +85°C, VCC = 5.5V
µA
When device is in idle mode, VCC = 3.3V,
VSDA & VSCL < 0.3V or > > VCC-0.3
nA
When device is in sleep mode, VCC ≤ 3.6V,
VSDA & VSCL < 0.3V or > VCC-0.3, TA ≤ 55°C
µA
When device is in sleep mode
Output Low Voltage
VOL
0.4
V
When device is in active mode, VCC = 2.5 – 5.5V
Output Low Current
IOL
4
mA
When device is in active mode, VCC = 2.5 – 5.5V,
VOL = 0.4V
VIH and VIL Specifications
The input voltage thresholds when in sleep or idle mode are dependent on the VCC level as follows:
Figure 7-4. VIH and VIL When in Sleep or Idle Mode
VIH, VIL when in Sleep or Idle Mode
1.60
1.40
1.20
Vin
7.4.1
2
VIH
VIL
1.00
0.80
0.60
0.40
2.0
3.0
4.0
5.0
6.0
VCC
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When the device is active (not in sleep or idle mode), the input voltage thresholds are different, depending on the state of
TTLenable (bit three) within the I2C_Address byte stored in the configuration zone of the EEPROM. When a common voltage
is used for the ATSHA204 VCC pin and the input pull-up resistor, then this bit should be set to a one, which permits the input
thresholds to track the supply as follows:
Figure 7-5. VIH and VIL (Device Active, TTLenable = 1) – All I/O Interfaces
VIH, VIL when TTLenable is 1
3.20
3.00
2.80
2.60
2.40
2.20
Vin
2.00
VIH
1.80
VIL
1.60
1.40
1.20
1.00
0.80
0.60
0.40
2.0
3.0
4.0
5.0
6.0
Vcc
If the voltage supplied to the VCC pin of the ATSHA204 is different from the system voltage to which the input pull-up resistor is
connected, then the system designer may chose to set TTLenable to zero, which enables a fixed input threshold according to
the following table.
Table 7-6.
VIL and VIH (Device Active, TTLenable = 0) – All I/O Interfaces
Parameter
Symbol
Min
Input Low Voltage
VIL
Input High Voltage
VIH
Typ
Max
Unit
Notes
GND0.5
0.5
V
When device is active and TTLenable bit in
configuration memory is zero; otherwise, see
above.
1.5
VCC +
0.5
V
When device is active and TTLenable bit in
configuration memory is zero; otherwise, see
above.
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8.
Commands
8.1
I/O Blocks
Regardless of the I/O protocol being used (single-wire or I2C), commands are sent to the device, and responses received from
the device, within a block that is constructed in the following way:
Table 8-1.
I/O blocks
Byte #
Name
Meaning
0
Count
Number of bytes to be transferred to (or from) the device in the block, including count byte,
packet bytes, and checksum bytes. The count byte should, therefore, always have a value of
(N+1), where N is equal to the number of bytes in the packet plus the two checksum bytes. Thus,
for a block with one count byte, 50 packet bytes, and two checksum bytes, the count byte should
be set to 53. The maximum size block (and value of count) is 84 bytes, and the minimum size
block is four bytes. Values outside this range will cause unpredictable operation.
1 to (N-2)
Packet
Command, parameters and data, or response. See below for more details.
N-1, N
Checksum
CRC-16 verification of the count and packet bytes. The CRC polynomial is 0x8005. The initial
register value should be zero. After the last bit of the count and the packet have been
transmitted, the internal CRC register should have a value that matches the checksum bytes in
the block. The first CRC byte transmitted (N-1) is the least-significant byte of the CRC value, and
so the last byte of the block is the most-significant byte of the CRC.
The ATSHA204 is designed in such a way that the count value in the input block should be consistent with the size
requirements specified in the command parameters. If the count value is inconsistent with the command opcode and/or
parameters within the packet, the ATSHA204 will respond in different ways, depending on the specific command. Either the
response may include an error indication or some input bytes may be silently ignored.
8.1.1
Command Packets
The command packet is broken down as shown in Table 8-2.
Table 8-2.
Command packets
Byte #
Name
Meaning
0
Opcode
The Command Code – see Section 8.1.4
1
Param1
The First Parameter – always present
2-3
Param2
The Second Parameter – always present
4+
Data
Optional remaining input data
After the ATSHA204 receives all the bytes in a block, the device transitions to the busy state and attempts to execute the
command. Neither status nor results can be read from the device when it is busy. During this time, the device’s I/O interface
ignores all SDA transitions regardless of the I/O interface selected. The command execution delays are listed in Section 8.1.4.
If insufficient bytes are sent to the device when it is in one-wire mode, the device automatically transitions to the low-power
sleep state after the tTIMEOUT interval. In I2C mode, the device continues to wait for the remaining bytes until the watchdog timer
limit, tWATCHDOG, is reached or a start/stop condition is received by the device.
In the individual command description tables below in Sections 8.2 through 8.13, the size column describes the number of
bytes in the parameter documented in each particular row. If the input block size for a particular command is incorrect, the
device does not attempt to execute the command; instead, the device returns an error.
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8.1.2
Status/Error Codes
The device does not have a dedicated status register, and so the output FIFO is shared among status, error, and command
results. All output from the device is returned to the system as complete blocks, which are formatted identically to input blocks:
•
•
•
Count
Packet
2-byte CRC
After the device receives the first byte of an input command block, the system cannot read anything from the device until the
system has sent all the bytes to the device.
After wake and after execution of a command, there will be error, status, or result bytes in the device’s output register that can
be retrieved by the system. When the length of that block is four bytes, the codes returned are detailed below in Table 8-3.
Some commands return more than four bytes when they execute successfully: the resulting packet description is listed in the
command section below.
CRC errors are always returned before any other type of error. They indicate that some sort of I/O error occurred and that the
command may be resent to the device. If a command includes both parse and execution errors, there is no particular
precedence enforced – an execution error may occur before a parse error and/or the reverse.
Table 8-3.
Status/error Codes in 4-byte Blocks
State Description
Error/Status
Description
Successful
Command Execution
0x00
Command executed successfully.
Checkmac
Miscompare
0x01
The CheckMac command was properly sent to the device, but the input client
response did not match the expected value.
Parse Error
0x03
Command was properly received, but the length, command opcode, or parameters
are illegal, regardless of the state (volatile and/or EEPROM configuration) of the
ATSHA204.
Changes in the value of the command bits must be made before it is re-attempted.
Execution Error
0x0F
Command was properly received, but could not be executed by the device in its
current state.
Changes in the device state or the value of the command bits must be made
before it is re-attempted.
After Wake, but prior
to first command
0x11
Indication that the ATSHA204 has received a proper wake token.
CRC or other
Communications
Error
0xFF
Command was not properly received by the ATSHA204, and should be
re-transmitted by the I/O driver in the system.
No attempt was made to parse or execute the command.
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8.1.3
Command Opcodes, Short Descriptions, and Execution Times
During parsing of the parameters and subsequent execution of a properly received command, the device will be busy and not
respond to transitions on the pins. The interval during which the device will be busy varies depending on the command and its
parameter values, the state of the device, the environmental conditions, and other factors per the table below.
Table 8-4.
Command Opcodes, Short Descriptions, and Execution Times
Typ. Exec.
1
Time , ms
Max. Exec.
2
Time , ms
Derive a target key value from the target or parent key.
14
62
0x30
Return device revision information.
0.4
2
GenDig
0x15
Generate a data protection digest from a random or input seed and a
key.
11
43
HMAC
0x11
Calculate response from key and other internal data using
HMAC/SHA-256.
27
69
CheckMac
0x28
Verify a MAC calculated on another Atmel CryptoAuthentication device.
12
38
Lock
0x17
Prevent further modifications to a zone of the device.
5
24
MAC
0x08
Calculate response from key and other internal data using SHA-256.
12
35
Nonce
0x16
Generate a 32-byte random number and an internally stored nonce.
22
60
Pause
0x01
Selectively put just one device on a shared bus into the idle state.
0.4
2
Random
0x1B
Generate a random number.
11
50
Read
0x02
Read four bytes from the device, with or without authentication and
encryption.
0.4
4
UpdateExtra
0x20
Update bytes 84 or 85 within the configuration zone after the
configuration zone is locked.
8
12
Write
0x12
Write 4 or 32 bytes to the device, with or without authentication and
encryption.
4
42
Command
Opcode
Description
DeriveKey
0x1C
DevRev
Notes:
1.
Typical execution times are representative of the duration to execute the command assuming no error
conditions, fastest mode setting, no optional internal actions such as limited use keys, and favorable
environmental conditions. For best performance, delay for this interval and then start polling to determine actual
command completion.
2. Maximum execution times are representative of the longest duration of a successful command execution with all
mode and internal actions enabled under extended statistical and environmental conditions. Execution time may
extend beyond these values in extreme situations. In most but not all cases, failing commands will return
relatively quickly, often well before the typical execution time.
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8.1.4
Address Encoding
The Read and Write commands include a single address in Param2 that indicates the memory to be accessed. All Reads and
Writes are in units of four bytes (one word). The most-significant byte of a legal ATSHA204 address is always zero. All unused
address bits should always be set to zero. The least-significant bits in the address describe the offset to the first word to be
accessed within the block/slot, while the upper bits specify the block/slot number per the table below:
Table 8-5.
Zone
Address Encoding (Param2)
Byte 1
Byte 0
Unused
Unused
Block/Slot
Offset
Config
Bits 0  7
Bits 5  7
Bits 3  4
Bits 0  2
OTP
Bits 0  7
Bits 4  7
Bit 3
Bits 0  2
Data
Bits 0  7
Bit 7
Bits 3  6
Bits 0  2
Within each zone, there are various access restrictions per the table below:
Table 8-6.
Legal Block/slot Values
Legal Block/Slot
(inclusive)
Zone
Notes
Config
0-2
Addresses below 16 (block 0, offset 16) and above 87 (block 2, offset 23) can never be written.
Addresses above 87 can never be read. Both 4- and 32-byte reads/writes are permitted
OTP
0-1
When OTPmode is read-only, all offsets in both blocks are available to use with 4- or 32-byte
reads.
If OTPmode is consumption, then writes are also permitted to all offsets.
See Section 2.1.3 if OTPmode is Legacy.
Data
0-15
All offsets in all slots available for both read and write.
4-byte access permitted on a particular slot only if SlotConfig.IsSecret is zero.
In the table below, “Byte Address” is the byte address within the data zone for the first byte in the respective slot. Because all
Reads and Writes with the ATSHA204 are performed on a word (4-byte or 32-bit) basis, the word address in the table below
should be used for the address parameter passed to the Read and Write commands.
Table 8-7.
Data Zone Slots
Slot #
Byte Address
(Hex)
Word Address
(Hex)
Slot #
Byte Address
(Hex)
Word Address
(Hex)
0
0x0000
0x0000
8
0x0100
0x0040
1
0x0020
0x0008
9
0x0120
0x0048
2
0x0040
0x0010
10
0x0140
0x0050
3
0x0060
0x0018
11
0x0160
0x0058
4
0x0080
0x0020
12
0x0180
0x0060
5
0x00A0
0x0028
13
0x01A0
0x0068
6
0x00C0
0x0030
14
0x01C0
0x0070
7
0x00E0
0x0038
15
0x01E0
0x007F
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8.1.5
Zone Encoding
The value in Param1 controls which zone the command accesses. See Section 2.1.2.1, “Configuration Zone Locking,” to
obtain more information on what controls the “locked” and “unlocked” states for each zone. All other zone values are reserved,
and should not be used.
Table 8-8.
8.1.6
Zone Encoding (Param1)
Zone
Name
Param1
Value
Config
Size
Read
Write
0
512 bits,
64 bytes,
2 slots
Always available
Partially, when unlocked
Never when locked
Never encrypted
OTP
1
512 bits,
64 bytes,
2 slots
Never when unlocked. Always
when locked, except in legacy
mode. See Section 2.1.3
All writeable when unlocked using Write
When locked, write permissions depend on OTPmode
See Section 2.1.3
Data
2
4096 bits,
512 bytes,
16 slots
Never when unlocked.
Otherwise, controlled by
IsSecret and EncryptRead.
All writeable when unlocked
When locked, writes controlled by WriteConfig
Watchdog Failsafe
A watchdog counter starts within the device after the ATSHA204 receives a wake token. After tWATCHDOG, the device enters
sleep mode, regardless of whether some I/O transmission or command execution is in progress. There is no way to reset the
counter other than to put the device into sleep or idle mode and then wake it up again.
The watchdog timer is implemented as a failsafe mechanism so that no matter what happens on either the system side or
inside the device, including any I/O synchronization issue, power consumption will fall to the ultra-low sleep level automatically.
The device resets the values stored in the SRAM and internal status registers when it transitions to the sleep state. However, if
the device is explicitly put into the idle mode through the appropriate I/O sequence, the device retains the contents of the two
SRAM registers (TempKey and RNG seed).
Normally, all command sequences must complete within tWATCHDOG if they require state that is stored in the SRAM registers.
The system software can use this idle mode mechanism to implement a longer command sequence than can be completed
during a single watchdog interval.
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8.2
CheckMac Command
The CheckMac command calculates a MAC response that would have been generated on a CryptoAuthentication device and
compares that with an input value. It returns a Boolean to indicate the success or failure of the comparison.
Prior to running this command, the Nonce and/or GenDig commands may have been optionally run to create a key or nonce
value in TempKey. The input mode parameter determines the source of the “key” (the first 32 bytes of the SHA message) and
“challenge/nonce” (the second 32 bytes of the SHA message).
If the comparison matches, then the target EEPROM slot value may be copied into TempKey. If KeyID is even, then the target
slot is KeyID+1, else the target slot is KeyID. For the copy to take place, the mode parameter to CheckMac must have a value
of 0x01 and SlotConfig.ReadKey for the target key must be zero. When CheckMac is loaded in this manner, it will not be
retained when the device enters the idle state
Table 8-9.
Input parameters
Name
Size
Notes
Opcode
CHECKMAC
1
0x28
Param1
Mode
1
Bit 0: If zero, the second 32 bytes of the SHA message are taken from the input
ClientChal parameter. If one, the second 32 bytes of the message are taken
from TempKey.
Bit 1: If zero, use key[KeyID] in first SHA block. If one, use TempKey.
Bit 2: If Mode:0 or Mode:1 are set, then the value of this bit must match the value in
TempKey.SourceFlag or the command will return an error.
Bit 5: If one, use 64 bits of OTP zone in calculation. If zero, use 64 zeros.
Bits 3-4 and 6-7: Must be zero.
Param2
KeyID
2
Which internal key is to be used to generate the response. All but bits 0:3 are ignored.
Data1
ClientChal
32
Challenge sent to client. If Mode:0 is one, then the value of this parameter will be
ignored (though these 32 bytes MUST still appear in the input stream).
Data2
ClientResp
32
Response generated by the client.
Data3
OtherData
13
Remaining constant data needed for response calculation.
Table 8-10. Output parameter
Name
Size
Result
1
Notes
Returns a single byte with a value of zero if ClientResp matches the internally
computed digest, one if there is a mismatch.
The message that will be hashed with the SHA-256 algorithm consists of the following information:
32 bytes
key[KeyID] or TempKey (depending on mode)
32 bytes
ClientChal or TempKey (depending on mode)
4 bytes
OtherData[0:3]
8 bytes
OTP[0:7] (or 0s depending on mode)
3 bytes
OtherData[4:6]
1 byte
SN[8]
4 bytes
OtherData[7:10]
2 bytes
SN[0:1]
2 bytes
OtherData[11:12]
Atmel ATSHA204 [DATASHEET]
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8.3
DeriveKey Command
The device combines the current value of a key with the Nonce stored in TempKey using SHA-256, and places the result into
the target key slot. SlotConfig[TargetKey]. Bit13 must be set or DeriveKey will return an error.
If SlotConfig[TargetKey].Bit12 is zero, the source key that will be combined with TempKey is the target key specified in the
command line (Roll Key operation). If SlotConfig[TargetKey].Bit12 is one, the source key is the parent key of the target key,
which is found in SlotConfig[TargetKey].WriteKey (Create Key operation).
Prior to execution of this command, the Nonce command must have been run to create a valid nonce in TempKey. Depending
on the state of bit two of the input mode, this nonce must have been created with the internal random number generator, or it
must have been fixed.
If SlotConfig[TargetKey].Bit15 is set, an input MAC must be present and have been computed as:
SHA-256(ParentKey, Opcode, Param1, Param2, SN[8], SN[0:1])
where the ParentKey ID is always SlotConfig[TargetKey].WriteKey.
If SlotConfig[TargetKey].Bit12 or SlotConfig[TargetKey].Bit15 is set and SlotConfig[ParentKey].SingleUse is also set,
DeriveKey returns an error if UseFlag[ParentKey] is 0x00. DeriveKey ignores SingleUse and UseFlag for the target key if
SlotConfig[TargetKey].Bit12 and SlotConfig[TargetKey].Bit15 are both zero.
For slots 0-7 only, if input parsing and the optional MAC check succeed, UseFlag[TargetKey] gets set to 0xFF and
UpdateCount[TargetKey] is incremented. If UpdateCount currently has a value of 255, it wraps to zero. If the command fails for
any reason, these bytes are not updated. The value of UpdateCount may be corrupted if power is interrupted during the
execution of DeriveKey.
Note:
If the source and target key are the same, there is a risk of permanent loss of the key value if power is
interrupted during the write operation. If the configuration bits permit it, the key slot may be recovered using an
authenticated and encrypted write based on the parent key.
Table 8-11. Input Parameters
Name
Size
Notes
Opcode
DERIVEKEY
1
0x1C
Param1
Random
1
Bit 2: The value of this bit must match the value in TempKey.SourceFlag or the
command will return an error.
Bits 0:1, 3:7: Must be zero.
Param2
TargetKey
Data
Mac
2
0 or 32
Key slot to be written.
Optional MAC used to validate operation.
Table 8-12. Output parameter
Name
Success
Size
1
Notes
Upon successful completion, the ATSHA204 returns a value of zero.
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The key written to the target slot is the result of a SHA-256 of the following message:
32 bytes
Target or parent key (depending on SlotConfig Bit12)
1 byte
Opcode
1 byte
Param1
2 bytes
Param2
1 byte
SN[8]
2 bytes
SN[0:1]
25 bytes
Zeros
32 bytes
TempKey.value
The data flow for this command is shown graphically in the figure below:
Figure 8-1. Data Flow for DeriveKey Command
Parent
Key
Target
Key
Mode
SHA
(AUTH)
Source
Key
Nonce
SHA
(Derive)
Input MAC
Match
Atmel ATSHA204 [DATASHEET]
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8.4
DevRev Command
DevRev command returns a single four-byte word representing the revision number of the device. Software should not depend
on this value as it may change from time to time.
Table 8-13. Input Parameters
Name
Size
Notes
Opcode
DEVREV
1
0x30
Param1
Mode
1
Must be zero.
Param2
-
2
Must be zero.
Data
-
0
-
Table 8-14. Output Parameters
Name
Success
Size
4
Notes
The current device revision number.
Atmel ATSHA204 [DATASHEET]
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8.5
GenDig Command
Uses SHA-256 to combine a stored value with the contents of TempKey, which must have been valid prior to the execution of
this command. The stored value can come from one of the data slots, either of the OTP pages, either of the first two pages of
the configuration zone, or retrieved from the hardware transport key array. The resulting digest is retained in TempKey, and
can be used in one of three ways:
1.
2.
3.
It can be included as part of the message used by the MAC, CheckMac, or HMAC commands. Because the MAC
response output incorporates both the data used in the GenDig calculation and the secret key from the MAC
command, it serves to authenticate the data stored in the data and/or OTP zones.
A subsequent Read or Write command can use the digest to provide authentication and/or confidentiality for the
data, in which case it is known as a data protection digest.
You can use this command for secure personalization by using a value from the transport key array. The resulting
data protection digest would then be used by the Write Command.
If Zone is two (Data) and KeyID is ≤15, the GenDig command sets TempKey.GenData to one and TempKey.KeyID to the input
KeyID; otherwise, TempKey.GenData is set to zero.
Regardless of how the resulting digest is computed, it can never be read from the device.
If TempKey.Valid is invalid, this command returns an error. Upon command completion, the TempKey.Valid bit is set,
indicating that a digest has been loaded and is ready for use. The TempKey.Valid bit is cleared when the next command is
executed. See Section 2.2 for more details.
For all KeyID values less than 0x8000, the device uses the least-significant four bits of KeyID to determine the slot number
from which to retrieve the key value from the data zone of the EEPROM. KeyID values above 0x8000 reference keys stored in
the masks of the design. In any event, all 16 bits of KeyID as input to the device are used as Param2 in the SHA-256
calculation.
If the Zone parameter points to the configuration zone, then this command returns an error if the configuration zone is
unlocked.
When the key specified on input to GenDig has the CheckOnly bit set, GenDig can be used to generate ephemeral keys
matching those generated on client CryptoAuthentication devices using the DeriveKey command. Keys that have the
CheckOnly bit set represent situations in which the device is acting as a host. In this case, the opcode and parameter bytes
that would normally be included in the SHA calculation are replaced with bytes from the input stream.
Table 8-15. Input parameters
Name
Size
Notes
Opcode
GENDIG
1
0x15
Param1
Zone
1
If 0x00 (Config): Use KeyID to specify either the first (KeyID=0) or second (KeyID = 1)
256-bit block of the configuration zone.
If 0x01 (OTP): Use KeyID to specify either the first or second 256-bit block of the OTP
zone.
If 0x02 (Data): KeyID specifies a slot in the data zone or a transport key in the hardware
array.
All other values are reserved and must not be used.
Param2
KeyID
2
Identification number of the key to be used, or selection of which OTP block.
Data
OtherData
4 or 0
4 bytes of data for SHA calculation when using a CheckOnly key; otherwise ignored.
Table 8-16. Output parameter
Name
Success
Size
1
Notes
Upon successful execution, the Atmel ATSHA204 returns a value of zero.
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If Zone is data and SlotConfig[KeyID].CheckOnly is one, the SHA-256 message body used to create the resulting new
TempKey consists of the following bytes:
32 bytes
Data.slot[KeyID]
4 bytes
OtherData
1 byte
SN[8]
2 bytes
SN[0:1]
25 bytes
Zeros
32 bytes
TempKey.value
In all other cases, the message use to create TempKey is as follows:
32 bytes
Config[KeyID] or OTP[KeyID] or Data.slot[KeyID] or TransportKey[KeyID]
1 byte
Opcode
1 byte
Param1
2 bytes
Param2
1 byte
SN[8]
2 bytes
SN[0:1]
25 bytes
Zeros
32 bytes
TempKey.value
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8.6
HMAC Command
Computes a HMAC/SHA-256 digest of a key stored in the device, a challenge, and other information on the device. The output
of this command is the output of the HMAC algorithm computed over this key and message. If the message includes the serial
number of the device, the response is said to be diversified.
The normal command flow to use this command is as follows:
1.
Run Nonce command to load input challenge and optionally combine it with a generated random number. The result
of this operation is a nonce stored internally on the device.
Optionally run GenDig command to combine one or more stored EEPROM locations in the device with the nonce.
The result is stored internally in the device.
Run this HMAC command to combine the output of steps one (and step two if desired) with an EEPROM key to
generate an output response.
2.
3.
Step two addresses multiple use models. If the data in the EEPROM is a key, GenDig has the effect of authenticating the
challenge with multiple secret keys. Alternatively, if the contents of the slot are data (which does not have to necessarily even
be secret), GenDig has the effect of authenticating the value stored in that location.
Table 8-17. Input parameters
Name
Size
Notes
Opcode
HMAC
1
0x11
Param1
Mode
1
Controls which fields within the device are used in the message.
Param2
KeyID
2
Which key is to be used to generate the response.
Bits 0:3 only are used to select a slot but all 16 bits are used in the HMAC message.
Data
-
0
-
Table 8-18. Output parameter
Name
Size
Response
32
Notes
HMAC digest
The HMAC digest is computed using the key at KeyID as the HMAC key over a message consisting of the following
information:
32 bytes
Zeros
32 bytes
TempKey
1 byte
Opcode (always 0x11)
1 byte
Mode
2 bytes
KeyID
8 bytes
OTP[0:7] (or zeros, see Table 8-19)
3 bytes
OTP[8:10] (or zeros, see Table 8-19)
1 byte
SN[8] bits (never zeroed out)
4 bytes
SN[4:7] bits (or zeros, see Table 8-19)
2 bytes
SN[0:1] (never zeroed out)
2 bytes
SN[2:3] (or zeros, see Table 8-19)
Atmel ATSHA204 [DATASHEET]
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See the NIST HMAC specification for a complete description of how the various digests are calculated using SHA-256, the
HMAC key, and appropriate padding. See http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf. The padding is part of the
SHA-256 message (see Section 3.1). HMAC is a construct that sits on top of SHA-256.
Table 8-19. Mode Encoding
Bits
Meaning
7
Must be zero.
6
If set, include the 48 bits SN[2:3] and SN[4:7] in the message.
Otherwise, the corresponding message bits are set to zero.
5
Include the first 64 OTP bits (OTP[0] through OTP[7]) in the message.
Otherwise, the corresponding message bits are set to zero.
If Mode[4] is set, the value of this mode bit is ignored.
4
Include the first 88 OTP bits (OTP[0] through OTP[10]) in the message.
Otherwise, the corresponding message bits are set to zero.
3
Must be zero.
2
The value of this bit must match the value in TempKey.SourceFlag or the command will return an error.
0-1
Must be zero.
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8.7
Lock Command
Write either LockConfig or LockValue to 0xFF, thereby changing the permissions in the designated zone.
This command fails if the designated zone is already locked.
Prior to locking the device, the ATSHA204 uses the CRC-16 algorithm to generate a summary digest of the designated
zone(s). The calculation is made identically to the CRC computed over the input and output blocks.
•
•
For the configuration zone, the CRC is calculated over all 88 bytes.
For the data and OTP zones, their contents are concatenated in that order to create the input to the CRC algorithm.
If the input summary does not match that computed on the device, an error is returned and the personalization process should
be repeated.
Table 8-20. Input Parameters
Name
Size
Notes
Opode
LOCK
1
0x17
Param1
Zone
1
Bit 0: Zero for config zone, 1 for data and OTP zones.
Bits 1-6: Must be zero.
Bit 7: If one, the check of the zone CRC is ignored and the zone is locked, regardless
of the state of the memory. Atmel does not recommend using this mode.
Param2
Summary
2
Summary of the designated zones, or should be 0x0000 if Zone[7] is set.
Data
-
0
-
Table 8-21. Output Parameter
Name
Success
Size
1
Notes
Upon successful execution, the Atmel ATSHA204 returns a value of zero.
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8.8
MAC Command
Computes a SHA-256 digest of a key stored in the device, a challenge, and other information on the device. The output of this
command is the digest of this message. If the message includes the serial number of the device, the response is said to be
diversified.
The normal command flow to use this command is as follows:
1.
Run Nonce command to load input challenge and optionally combine it with a generated random number. The result
of this operation is a nonce stored internally on the device.
Optionally run GenDig command to combine one or more stored EEPROM locations in the device with the nonce.
The result is stored internally in the device. This capability permits two or more keys to be used as part of the
response generation.
Run this MAC command to combine the output of step one (and step two if desired) with an EEPROM key to
generate an output response (or digest).
2.
3.
Alternatively, data in any slot (which does not have to necessarily even be secret) can be accumulated into the response
through the same GenDig mechanism. This has the effect of authenticating the value stored in that location.
Table 8-22. Input Parameters
Name
Size
Notes
Opcode
MAC
1
0x08
Param1
Mode
1
Controls which fields within the device are used in the message.
Param2
KeyID
2
Which internal key is to be used to generate the response.
Bits 0:3 only are used to select a slot but all 16 bits are used in the SHA-256 message.
Data
Challenge
0 or 32
Input portion of message to be digested, ignored if Mode:0 is one.
Table 8-23. Output Parameter
Name
Size
Response
32
Notes
SHA-256 digest
The message that will be hashed with the SHA-256 algorithm consists of the following information:
32 bytes key[KeyID] or TempKey (See Table 8-24)
32 bytes Challenge or TempKey (See Table 8-24)
1 byte
Opcode (always 0x08)
1 byte
Mode
2 bytes Param2
8 bytes OTP[0:7] (or zeros, see Table 8-24)
3 bytes OTP[8:10] (or zeros, see Table 8-24)
1 byte
SN[8] bits (never zeroed out)
4 bytes SN[4:7] bits (or zeros, see Table 8-24)
2 bytes SN[0:1] (never zeroed out)
2 bytes SN[2:3] (or zeros, see Table 8-24)
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Table 8-24. Mode Encoding
Bits
Meaning
7
Must be zero.
6
If set, include the 48 bits SN[2:3] and SN[4:7] in the message.
Otherwise, the corresponding message bits are set to zero.
5
Include the first 64 OTP bits (OTP[0] through OTP[7]) in the message.
Otherwise, the corresponding message bits are set to zero.
If Mode[4] is set, the value of this mode bit is ignored.
4
Include the first 88 OTP bits (OTP[0] through OTP[10]) in the message.
Otherwise, the corresponding message bits are set to zero.
3
Must be zero.
2
If either Mode:0 or Mode:1 are set, Mode:2 must match the value in TempKey.SourceFlag or the command will
return an error.
1
If zero, the first 32 bytes of the SHA message are loaded from one of the data slots.
If one, the first 32 bytes are filled with TempKey.
0
If zero, the second 32 bytes of the SHA message are taken from the input Challenge parameter.
If one, the second 32 bytes are filled with the value in TempKey. This mode is recommended for all use.
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8.9
Nonce Command
This command generates a nonce for use by a subsequent GenDig, MAC, HMAC, Read, or Write command by combining an
internally generated random number with an input value from the system. The resulting Nonce is stored internally in TempKey
and the generated random number is returned to the system.
The input value is designed to prevent replay attacks against the host ─ it must be externally generated by the system and
passed into the device using this command. It may be any value that changes consistently, such as a nonvolatile counter,
current real time of day, and so on, or it can be an externally generated random number.
To provide a Nonce value for subsequent crypto commands, the input number and output random number are hashed
together per the information listed below. The resulting digest (nonce) is always stored in the TempKey register,
TempKey.Valid is set, and TempKey.SourceFlag is set to “Rand.” The Nonce can be used by a subsequent GenDig, Read,
Write, HMAC, or MAC command – thus, the system must externally compute this digest value and store it externally to
complete the execution of those commands.
Alternatively, this command can also be run in a pass-through mode if a fixed nonce is required for subsequent commands. In
this case, the input value must be 32 bytes long, and it is passed directly to TempKey without modification. No SHA-256
calculation is performed, and TempKey.SourceFlag is set to “Input.” The nonce value in TempKey may not be used with Read
or Write commands. If operated in this mode and with a repeated input number value, the device provides no protection
against replay attacks.
Prior to the configuration section being locked, the random number generator produces a value of 0xFF FF 00 00 FF FF 00 00
to facilitate testing. This test value is combined with the input value in the manner described above.
Table 8-25. Input Parameters
Name
Size
Notes
Opode
Nonce
1
0x16
Param1
Mode
1
Controls the mechanism of the internal random number generator and seed update.
Param2
Zero
2
Must be 0x0000.
Data
NumIn
20,32
Input value from system.
Table 8-26. Output Parameter
Name
Size
RandOut
1 or 32
Notes
The output of the random number generator or a single byte with a value of zero if
Mode[0:1] is three.
If Mode[0:1] is zero or one, the input NumIn parameter must be 20 bytes long, and the SHA-256 message body used to create
the nonce stored internally in TempKey consists of the following:
32 bytes
RandOut
20 bytes
NumIn from input stream
1 byte
Opcode (always 0x16)
1 byte
Mode
1 byte
LSB of Param2 (should always be 0x00)
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Upon completion of the command, TempKey.SourceFlag is set to “Rand.”
If Mode[0:1] is three, this command operates in pass-through mode, the input parameter (NumIn) must be 32 bytes long, and
TempKey is loaded with NumIn. No SHA-256 calculation is performed, no data is returned to the system, and
TempKey.SourceFlag is set to “Input.”
If Mode[0:1] is one, the automatic seed update is suppressed. See Section 3.4.2 for more details.
Table 8-27. Mode Encoding
Bits
Meaning
2-7
Must be zero.
0-1
0: Combine new random number with NumIn, store in TempKey. Automatically update EEPROM seed only if
necessary prior to random number generation. Recommended for highest security.
1: Combine new random number with NumIn, store in TempKey. Generate random number using existing
EEPROM seed, do NOT update EEPROM seed.
2: Invalid
3: Operate in pass-through mode and write TempKey with NumIn.
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8.10
Pause Command
All devices on the bus for which the configuration Selector byte does not match the input selector parameter will go into the
idle state. This command is used to prevent bus conflicts in a system that includes multiple ATSHA204 devices sharing the
same bus.
This command differs from the idle flag/sequence in that individual devices on the single pin bus may be selected to go into
the idle state, as opposed to the idle flag which causes all the CryptoAuthentication devices on the bus into the idle state.
If the EEPROM Selector byte does not match the input selector parameter, the device will immediately go to the idle state and
no result information will be available. If the input selector parameter does match the configuration selector byte, the device
returns a success code of 0x00.
The pause command cannot be used to put the devices into the sleep state.
Table 8-28. Input Parameters
Name
Size
Notes
Opode
PAUSE
1
0x01
Param1
Selector
1
All devices that do not match this value go to idle state.
Param2
Zero
2
Must be 0x0000
Data
-
0
-
Table 8-29. Output Parameter
Name
Success
Size
1
Notes
If the command indicates that some other device should idle, the Atmel ATSHA204
returns a value of 0x00.
If this device goes to idle, no value is returned.
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8.11
Random Command
This command generates a random number for use by the system.
Random numbers are generated through a combination of the output of a hardware random number generator and an internal
seed value stored in the EEPROM or SRAM. The external system may choose to update the internally stored EEPROM seed
value prior to the generation of the random number as part of the execution of the nonce or random command, though the
endurance limitations of the EEPROM limit the number of times that this update can be performed. After the endurance limit
has been reached, attempts to update the EEPROM seed return an error.
The random command does not provide a mechanism to integrate an input number with the internal stored seed. If this
functionality is desired, the system should use the Nonce command and ignore the generated nonce.
Prior to the configuration section being locked, the random number generator produces a value of 0xFF, 0xFF, 0x00, 0x00,
0xFF, 0xFF, 0x00, 0x00 to facilitate testing.
Note:
The same internally stored seeds are used for both the Nonce and Random commands. Use of Mode=0 ensures
that the EEPROM is updated, if necessary.
Table 8-30. Input Parameters
Name
Size
Notes
Opode
RANDOM
1
0x1B
Param1
Mode
1
Controls the mechanism of the internal random number generator and seed update.
Param2
Zero
2
Must be 0x0000
Data
-
0
-
Table 8-31. Output Parameter
Name
Size
RandOut
32
Notes
The output of the random number generator.
Table 8-32. Mode Encoding
Bits
Meaning
1-7
Must be zero.
0
0: Automatically update EEPROM seed only if necessary prior to random number generation
Recommended for highest security.
1: Generate random number using existing EEPROM seed; do not update EEPROM seed.
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8.12
Read Command
Reads words (one 4-byte word or an 8-word block of 32 bytes) from one of the memory zones of the device. The data may
optionally be encrypted before being returned to the system. See also Section 8.1.5, “Zone Encoding,” and Section 8.1.4,
“Address Encoding,” for data zone byte and word addressing information.
If reading from a slot in which SlotConfig.EncryptRead is set, the GenDig command must have been run prior to the execution
of this command to generate the key that will be used for encryption. The input nonce to GenDig must have been a random
number, and the key specified in SlotConfig.ReadKey must have been used in the GenDig calculation.
The device encrypts data to be read by XORing each byte read from the EEPROM with the corresponding byte from
TempKey. Encrypted reads of the configuration and/or OTP zones are not permitted.
The byte addresses to be read should be divided by four (drop the least-significant two bits) before being passed to the device.
If 32 bytes are being read, the least-significant three bits of the input address are ignored. Addresses beyond the end of the
specified zone result in an error.
The following restrictions apply to the three zones:
Config
The words within this zone are always readable using this command, regardless of the value of LockConfig.
See Section 2.1.1, as some bytes are unreadable under any circumstances, and any attempt to read these
bytes result in an error.
OTP
If the OTP zone is unlocked, this command returns an error. Once locked, if OTPmode is set to a non-zero
value and the address points to either word zero or one, then the command also returns an error. Otherwise,
the corresponding word within the OTP zone is returned in the clear. If OTPmode is Legacy, then only four
byte reads are permitted.
Data
If the data zone is unlocked, this command returns an error. Otherwise, the values within the corresponding
SlotConfig word control access to the data slot. If SlotConfig.IsSecret is set and a four byte read is
attempted, the device returns an error. If EncryptRead is set, this command encrypts the data as specified
above. If IsSecret is set and EncryptRead is clear, this command returns an error. If IsSecret is clear and
EncryptRead is clear, this command returns the desired slot in the clear.
Table 8-33. Input Parameters
Name
Size
Notes
Opcode
READ
1
0x02
Param1
Zone
1
Bits 0 and 1: Select among config, OTP, or data. See Section 8.1.5.
Bits 2-6: Must be zero.
Bit 7: If one, 32 bytes are read; otherwise four bytes are read. Must be zero if reading from
OTP zone.
Param2
Address
2
Address of first word to be read within the zone. See Section 8.1.4.
Data
-
0
-
Table 8-34. Output Parameter
Name
Contents
Size
4 or 32
Notes
The contents of the specified memory location.
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If reading the data zone and the EncryptRead bit is set in the corresponding SlotConfig word, the following actions are taken to
encrypt the data:
All of the TempKey register bits must be properly set as follows, or this command returns an error:
TempKey.Valid == 1
TempKey.GenData == 1
TempKey.KeyID == SlotConfig.ReadKey
TempKey.SourceFlag == “Rand”
XOR the data from the memory zone with TempKey. Return as “Contents.”
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8.13
UpdateExtra Command
This command is used to update the values of the two “extra” bytes within the configuration zone (location 84 and 85) after the
configuration zone has been locked.
If the mode parameter indicates UserExtra at address 84:
If the current value in UserExtra (byte 84 of configuration zone) is zero, then UpdateExtra writes this byte with the LS byte
of NewValue and returns success.
If the current value in UserExtra is non-zero, the command returns an execution error.
If the mode parameter indicates selector at address 85:
If SelectorMode (byte 19 of the configuration zone) is non-zero and Selector (byte 85 of the configuration zone) is zero,
this command will write Selector with the LS byte of NewValue and return success. Once written to a non-zero value, it is
then locked against further updating.
If SelectorMode has a value of zero, indicating that no check of the current Selector should be made, this command
always updates Selector and always succeeds.
Table 8-35. Input Parameters
Name
Size
Notes
Opode
UPDATEEXTRA
1
0x20
Param1
Mode
1
Bit 0: If zero, update config byte 84.
If one, update config byte 85.
Bits1-7: Must be zero
Param2
NewValue
2
LSB: Value to optionally be written to location 84 or 85 in configuration zone.
MSB: Must be 0x00.
Data
-
0
-
Table 8-36. Output Parameter
Name
Success
Size
1
Notes
If the memory byte was updated, this command returns a value of 0x00
Otherwise, it returns an Execution error.
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8.14
Write Command
Writes either a one 4-byte word or an 8-word block of 32 bytes to one of the EEPROM zones on the device. Depending on the
value of the WriteConfig byte for this slot the data may be required to be encrypted by the system prior to being sent to the
device.
The following restrictions apply to writes within zones using this command:
Config
If the Config zone is locked or Zone:6 is set, this command returns an error. Otherwise the bytes are written
as requested. Any attempt to write any byte for which Writes are permanently prohibited (per Section 2.1.1)
results in a command error with no modifications to the EEPROM.
OTP
If the OTP zone is unlocked, all bytes can be written with this command. If the OTP zone is locked and the
OTPmode byte is read-only or legacy, then this command returns an error. Otherwise, OTP mode should be
consumption and this command sets to zero those bits in the OTP zone that correspond to the zero bits in
the input parameter value. When the OTP zone is locked, encrypted writes to it are never permitted
regardless of OTPmode.
Data
If the data zone is unlocked, all bytes in all zones can be written with either plain text or encrypted data.
After the data zone is locked, the values within the WriteConfig bytes control access to the data slots. If the
WriteConfig bits for this slot are set to “always”, the input data should be passed to the device in the clear. If
Bit:14 of SlotConfig is set to one, the input data should be encrypted and an input MAC calculated.
Four byte writes are only permitted in the data and OTP zones if all four of the following conditions are met:
•
•
•
•
SlotConfig.IsSecret must be zero.
SlotConfig.WriteConfig must be “always.”
The input data must not encrypted.
The data/OTP zones must be locked.
Four byte writes will return an error under all other circumstances.
The least significant three bits of Param2, Address[0:2], indicate the word within the block, or are ignored if an entire 32 byte
block is being written. Address[3:6] contains the slot number for writes to the data zone, or the block number for the Config
and OTP zones. Address values beyond the size of the specified zone result in the command returning an error.
Any attempt to write the OTP and/or data zones prior to the configuration section being locked results in the device returning
an error code.
8.14.1 Input Data Encryption
The input data may be encrypted to prevent snooping on the bus during personalization or system operation. The system
should encrypt the data by XOR’ing the plain text with the current value in TempKey. Upon receipt the device will XOR the
input data with TempKey to restore the plain text prior to writing to the EEPROM.
Whenever the input data is encrypted an authorizing input MAC is always required when writing the data zone. This MAC is
computed as:
SHA-256(TempKey, Opcode, Param1, Param2, SN[8], SN[0:1], <25 bytes of 0’s>, PlainTextData )
Prior to locking of the OTP/Data zones, Zone:6 is used to indicate to the device whether or not the input data is encrypted.
After locking of the OTP/Data zones, Zone:6 is ignored and only bit 14 of the slotConfig corresponding to the slot being written
is used to determine whether or not the input data is encrypted.
If data encryption is indicated, TempKey must be valid prior to this command being called, it must be the result of GenDig.
Specifically, this means that TempKey.Valid and TempKey.GenDig must both be set to one. Prior to data locking, any key can
be used to generate TempKey. After locking, the last slot used by GenDig for TempKey creation and stored in
TempKey.KeyID must match that in SlotConfig.WriteKey and the random number generator must have been used to originally
generate TempKey prior to GenDig.
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Table 8-37. Input Parameters
Name
Size
Notes
Opcode
Write
1
0x12
Param1
Zone
1
Bits 0 and 1: Select among config, OTP or data. See Section 8.1.5.
Bits 2-5: Must be zero.
Bit 6: If one, the input data must be encrypted. Must be zero if data/OTP zones are
locked.
Bit 7: If one, 32 bytes will be written; otherwise, four bytes are written.
Param2
Address
2
Address of first word to be written within the zone. See Section 8.1.4.
Data_1
Value
4 or 32
Information to be written to the zone; may be encrypted.
Data_2
Mac
0 or 32
Message authentication code to validate address and data.
Ignored if zone is unlocked.
Table 8-38. Output parameter
Name
Success
Size
1
Notes
Upon successful completion, the Atmel ATSHA204 returns a value of zero.
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9.
Compatibility
The ATSHA204 is designed to be upwards compatible with the AT88SA102S for field operation. Most systems designed to
use the AT88SA102S in client devices will work perfectly with the ATSHA204 in the client devices without any modification to
the host system software or hardware.
Host systems that utilize the AT88SA10HS host device will also interoperate properly with the ATSHA204 client device in
place of a previously used AT88SA102S client. However, the AT88SA10HS itself cannot be replaced with the ATSHA204
without software modifications. With the appropriate software updates, the ATSHA204 can implement all the functions of an
AT8810HS host device and continue to properly communicate with client AT88SA102S devices.
For compatibility with the AT88SA102S, the following values should be written to the memory of the ATSHA204:
1.
2.
3.
4.
5.
During configuration, OTPmode should be set to Legacy to hide the values of the first 64 bits of the OTP section,
which contain a secret in the Atmel AT88SA102S.
The same secret and status information that would have been written to the first 88 fuse bits of the Atmel
AT88SA102S should be written to the first 88 bits of the OTP section on the Atmel ATSHA204.
OTP bits 88 through 127 should be written with copies of the values stored in SN[4:8] within the configuration section
of the Atmel ATSHA204 device. The read command on legacy systems will always use the values in the OTP
section while the Atmel ATSHA204 always uses the values in the configuration zone during the computation of
cryptographic results.
The key slot identified by the least significant four bits of the Atmel AT88SA102S KeyID assigned to a particular
customer should be loaded with the Atmel-provided value for that key.
The SlotConfig bits for the key slot identified in step four should be set to: CheckOnly=0, SingleUse=0,
EncryptRead=0, IsSecret=1, WriteConfig=1000.
The following compatibility exceptions apply:
•
•
Those Atmel AT88SA102S systems using the BurnFuse command on the client device cannot be replaced with the
Atmel ATSHA204, as the corresponding command is not available on the Atmel ATSHA204. The same capability is
implemented with the Write command, but system software modifications are necessary.
Those Atmel AT88SA102S systems in which the system software reads and depends on a fixed value for the device
revision number (RevNum at ROM address one) will find a different value in the Atmel ATSHA204.
Note: This value is not guaranteed to be identical for all Atmel AT88SA102S devices.
•
•
•
•
Systems including multiple Atmel AT88SA102S and/or Atmel AT88SA10HS devices on a shared single-wire bus
cannot be replaced with the Atmel ATSHA204, as the Pause command operates differently.
The key diversification strategy implemented by the Atmel ATSHA204 (when operating as a host) is different from
the similar strategy used by the Atmel AT88SA10HS. The Atmel ATSHA204 can be used as a host authentication
device for Atmel ATSHA204 clients that include diversified keys, but those clients will not work interchangeably with
Atmel AT88SA102S clients.
Because of the difference in the nonvolatile memory technology and size, the secure personalization mechanism is
different on the Atmel ATSHA204 as compared to the Atmel AT88SA10HS and Atmel AT88SA102S. Users will need
to modify their manufacturing processes and procedures accordingly.
The Atmel ATSHA204 cannot replace a client Atmel AT88SA100S device used for batteries and other self-powered
systems.
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10.
Mechanical
10.1
Pinout
The device is offered in multiple packages: 3-lead SOT23, 8-lead SOIC, 8-lead TSSOP, 8-pad UDFN and a 3-lead contact
package intended for mechanical, not soldered, connection. The pinouts are as follows:
Table 10-1. Package Pinouts
10.2
Name
SOT23-3LD
SOIC-8LD, TSSOP-8LD, UDFN-8 pad
3-lead Contact
SDA
1
5
1
SCL
−
6
-
VCC
2
8
3
GND
3
4
2
NC
−
1, 2, 3, 7
-
Wiring Configuration for Single-wire Interface
Using the single-wire interface allows the connection of the ATSHA204 to a host using only a single pin (SDA) to transfer data
in both directions. This interface does not use the SCL pin. In this configuration, no bypass capacitor is required to connect the
device to the system.
To prevent forward biasing the internal diode and drawing current across power planes in the system, the resistor pull-up on
the SDA pin should either be connected to the same supply that is connected to the VCC pin or to a lower voltage rail.
If the signal levels for SDA are different from the VCC voltage, consult the parametric specifications section of this document to
ensure that the signal levels are such that excessive leakage current will be minimized when in sleep modes. This situation
might occur if the ATSHA204 device is physically distant from the bus master device and the supply voltage for the bus master
is different from the supply voltage for the ATSHA204.
Figure 10-1. Three-wire Configuration for Single-Wire Interface
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11.
Package Drawings
11.1
3-lead SOT23
e1
COMMON DIMENSIONS
(Unit of Measure = mm)
1. Dimension D does not include mold flash, protrusions or gate burrs. Mold flash,
protrusions or gate burrs shall not exceed 0.25mm per end. Dimension E1 does
not include interlead flash or protrusion. Interlead flash or protrusion shall not
exceed 0.25mm per side.
2. The package top may be smaller than the package bottom. Dimensions D and E1
are determined at the outermost extremes of the plastic body exclusive of mold
flash, tie bar burrs, gate burrs and interlead flash, but including any mismatch
between the top and bottom of the plastic body.
3. These dimensions apply to the flat section of the lead between 0.08mm and
0.15mm from the lead tip.
SYMBOL
A
A1
A2
D
E
E1
L1
e1
b
MIN
NOM
MAX
0.89
1.12
0.01
0.10
0.88
1.02
2.80 2.90 3.04
2.10
2.64
1.20 1.30 1.40
0.54 REF
1.90 BSC
0.30
0.50
NOTE
1,2
1,2
3
This drawing is for general information only. Refer to
JEDEC Drawing TO-236, Variation AB for additional
information.
Package Drawing Contact:
[email protected]
11/5/08
TITLE
3TS1, 3-lead, 1.30mm Body, Plastic Thin
Shrink Small Outline Package (Shrink SOT)
GPC
TBG
DRAWING NO.
REV.
3TS1
A
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
59
11.2
8-lead TSSOP
C
1
Pin 1 indicator
this corner
E1
E
L1
N
L
Top View
End View
A
b
A1
e
COMMON DIMENSIONS
(Unit of Measure = mm)
A2
SYMBOL
D
Side View
Notes:
1. This drawing is for general information onl
y. Refer to JEDEC
Drawing MO-153,
VariationAA, for proper dimensions,
tolerances, datums, etc.
2. Dimension D does not include mold Flash, protrusions or gate
burrs. Mold Flash, protrusions and gate burrs shall not exceed
0.15 mm (0.006 in) per side.
3. Dimension E1 does not include inter-lead Flash or protrusions.
Inter-lead Flash and protrusions shall not exceed 0.25 mm
(0.010 in) per side.
4. Dimension b does not include Dambar protrusion.
Allowable
Dambar protrusion shall be 0.08 mm total in excess of the b
dimension at maximum material condition. Dambar cannot be
located on the lower radius of the foot. Minimum space between
protrusion and adjacent lead is 0.07 mm.
5. Dimension D and E1 to be determined at Datum Plane H.
MIN
NOM
MAX
A
-
-
1.20
A1
0.05
-
0.15
A2
0.80
1.00
1.05
D
2.90
3.00
3.10
E
NOTE
2, 5
6.40 BSC
E1
4.30
4.40
4.50
3, 5
b
0.19
–
0.30
4
e
0.65 BSC
L
0.45
0.60
0.75
L1
1.00 REF
C
0.09
-
0.20
6/22/11
TITLE
GPC
Package Drawing Contact:
8X, 8-lead 4.4mm Body, Plastic Thin
[email protected] Shrink Small Outline Package (TSSOP)
TNR
DRAWING NO.
8X
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
REV.
D
60
11.3
8-pad UDFN
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
61
11.4
8-lead SOIC
C
1
E
E1
L
N
Ø
TOP VIEW
END VIEW
e
b
COMMON DIMENSIONS
(Unit of Measure = mm)
A
A1
D
SIDE VIEW
Notes: This drawing is for general information only.
Refer to JEDEC Drawing MS-012, Variation AA
for proper dimensions, tolerances, datums, etc.
SYMBOL MIN
A
1.35
NOM
MAX
–
1.75
A1
0.10
–
0.25
b
0.31
–
0.51
C
0.17
–
0.25
D
4.80
–
5.05
E1
3.81
–
3.99
E
5.79
–
6.20
e
L
NOTE
1.27 BSC
0.40
–
1.27
0°
–
8°
6/22/11
TITLE
Package Drawing Contact:
8S1, 8-lead (0.150” Wide Body), Plastic Gull
[email protected] Wing Small Outline (JEDEC SOIC)
GPC
SWB
DRAWING NO.
REV.
8S1
G
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
62
11.5
3-lead Contact
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
63
12.
Ordering Information
Atmel ordering code
Package type
Interface configuration
ATSHA204-SH-CZ-T
8-lead SOIC, tape and reel
Single-wire
ATSHA204-SH-DA-T
8-lead SOIC, tape and reel
I2 C
ATSHA204-SH-DA-B
8-lead SOIC, bulk in tubes
I2 C
ATSHA204-TH-CZ-T
8-lead TSSOP, tape and reel
Single-wire
ATSHA204-TH-DA-T
8-lead TSSOP, tape and reel
I2 C
ATSHA204-TSU-T
3-lead SOT23, tape and reel
Single-wire
ATSHA204-MAH-CZ-T
8-pad UDFN, tape and reel
Single-wire
ATSHA204-MAH-DA-T
8-pad UDFN, tape and reel
I2 C
ATSHA204-RBH-T
3-lead Contact, tape and reel
Single-wire
The part number (Atmel ordering code) does NOT appear on the package. These packages are marked only with a
manufacturing lot number which will likely change from shipment to shipment. Do not use the package marking for any
incoming inspection process.
13.
14.
Revision History
Doc. Rev.
Date
Comments
8740D
03/2012
Added RBH – 3-lead contact package.
8740C
07/2011
Table 8-4, Command Opcodes, Short Descriptions, and Execution Times.
- Change Update Extra command for Typ from 4 to 8 and Max from 6 to 12.
Change Mode:6 to Zone:6.
Edit/update Write Command section.
Update template.
8740B
04/2011
Document update.
8740A
03/2011
Initial document release.
Errata
The design should ensure that all I/O pin levels are within the datasheet limits of VSS-0.5V and VCC+0.5V. The same power
supply signal net should be used for both the I/O driver, the VCC pin on the SHA204 and any pull-up resistor on the SDA pin.
Failure to adhere to these requirements may result in increased susceptibility to latchup.
Atmel ATSHA204 [DATASHEET]
8740D−CRYPTO−3/12
64
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© 2012 Atmel Corporation. All rights reserved. / Rev.: 8740D−CRYPTO−3/12
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