ATMEL AT88SA100S Atmel cryptoauthentication battery authentication chip Datasheet

Atmel AT88SA100S
Atmel CryptoAuthentication Battery Authentication Chip
DATASHEET
Features
•
•
•
•
•
•
•
•
Secure battery authentication
Superior SHA-256 hash algorithm
Best in class 256-bit key length
Guaranteed unique 48-bit serial number
High speed single wire interface
Supply voltage: 2.7 – 5.25 V
<150 nA sleep current
Green compliant (exceeds RoHS) 3-pin SOT-23 package and
8-lead TSSOP or SOIC
Applications
•
•
•
•
•
•
Cell phones
PDA and smart phones
Portable media players
Digital cameras & camcorders
Cordless tools
Handheld devices
Figure 1.
Pin configurations
Pin name
Function
SIGNAL
Serial data, single-wire clock, and data
GND
Ground
VCC
Power supply
3-lead SOT-23
8-lead SOIC
NC
1
8
NC
NC
2
7
3
6
GND
4
5
VCC
NC
NC
SIGNAL
2
GND
8-lead TSSOP
VCC
3
1
SIGNAL
NC
NC
NC
GND
1
8
2
7
3
6
4
5
VCC
NC
NC
SIGNAL
8558F−CRYPTO−9/11
1.
Introduction
The Atmel® AT88SA100S is a small authentication chip that can be used to validate battery packs and other replaceable items
that contain a power source. It uses the industry leading SHA-256 hash algorithm to provide the ultimate level of security.
An industry leading key length of 256-bits prevents exhaustive attacks while multiple physical security features prevent
unauthorized disclosure of the secret key stored within the chip. This key is automatically erased when power is removed from
the AT88SA100S.
It is shipped with a guaranteed unique 48-bit serial number that is used in combination with an input challenge and the stored
secret key to generate a response that is unique for every individual AT88SA100S.
The chip also includes 80 one-time fuses that can be used to configure the system and/or retain permanent status. The values
in these fuses can also be locked to prevent modification.
1.1
Memory Resources
Sram
256-bits of SRAM are used for storage of a key. The LoadSram command provides a mechanism to
securely initialize this block during personalization. This memory will retain its value when the chip is
put/goes to sleep, so long as a supply voltage in excess of VRETAIN is still supplied to the chip.
MemValid
A single bit that tells whether or not SRAM contains valid data. It’s cleared when power is lost and set
when the SRAM is loaded with a secret key.
Fuse
Block of 128-fuse bits that can be read and written through the one wire interface. The first 8-bits are
lock bits that control burn ability on 16-bit words of the array. Fuse[88-95] are part of the manufacturing
ID values fixed by Atmel. Fuse[96-127] are part of the serial number programmed by Atmel which is
guaranteed to be unique. See Section 1.3 for more details on the Manufacturing ID and Serial Number.
ROM
Metal mask programmed memory. Unrestricted reads are permitted on the first 64-bits of this array. The
physical ROM will be larger and will contain other information that cannot be read.
ROM MfrID
Two bytes of ROM that specifies part of the manufacturing ID code. This value is assigned by Atmel
and is always the same for all chips of a particular model number. For the AT88SA100S, this value is
0x2301. (Appears on the bus: 0x0123), ROM MfrID can be read by accessing ROM bytes 0 and 1 of
Address 0.
ROM SN
Two bytes of ROM that can be used to identify chips among others on the wafer. These bits reduce the
number of fuses necessary to construct a unique serial number. The ROM SN is read by accessing
ROM bytes 2 and 3 of Address 0. The serial number can always be read by the system and is optionally
included in the message digested by the MAC command.
RevNum
Four bytes of ROM that are used by Atmel to identify the design revision of the AT88SA100S chip.
These bytes can be freely read as the four bytes returned from ROM Address 1, however system code
should not depend on this value as it may change from time to time.
Atmel AT88SA100S [DATASHEET]
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1.2
Fuse Map
The AT88SA100S chip incorporates 128 one-time fuses within the chip. Once burned, there is no way to reset the value of a
fuse. Fuses, with the exception of the manufacturing ID and serial number bits, which are initialized by Atmel, have a value of
one when shipped from the Atmel factory and transition to a zero when they are burned.
Table 1-1.
The 128 Fuses in the Atmel AT88SA100S Chip are Arranged in the Following Manner:
Fuse #
Name
Description
0–7
Fuse Lock Bits
Each bit, when zero, locks the current value of the corresponding 16-bit block of the
fuse array, see below for more details
8  83
Status Fuses
These fuses can be written with the BurnFuse command and can always be read with
the Read command. They are totally user-defined
84  87
Status Fuses
These fuses can be written with the BurnFuse command and can always be read with
the Read command. They are user-defined, but have special significance for the Pause
Long command. See Section 6.3
87
Fuse Disable
The MAC command ignores the values of Fuse[0-86] while this fuse is an one
Once it is burned to zero, the BurnSecure command is disabled
88  95
Fuse MfrID
See Section 1.3. Set by Atmel, cannot be modified in the field
96  127
Fuse SN
See Section 1.3. Set by Atmel, cannot be modified in the field
Fuse Lock Bits
These eight fuses can be used to prevent further writing of the status fuses. Bit 0, when burned, locks
Fuse[0-15] from being modified, Bit[1] locks Fuse[16-31] and so on up through bit five, which locks
Fuse[80-87]. Fuse[88-127] can never be modified with the BurnFuse command.
Note:
Status Fuses
These fuses can be used to store various information which are not secret. Their value can always be
determined using the Read command. They can be individually burned using the BurnFuse command.
Two common usage models for these fuses are:
1.
2.
1.3
Burning bit zero has the effect of preventing any changes to the current value of the lock bits
Consumption logging, i.e. burn one bit after every n uses, the host system keeps track of the
number of uses so far for this serial number since the last fuse burn.
Model number information. In this situation, the bits are written at the factory and their value is
locked to prevent modifications in the field. This method can also be used for feature enabling.
Chip Identification
The chip includes a total of 72-bits of information that can be used to distinguish between individual chips in a reliable manner.
The information is distributed between the ROM and fuse blocks in the following manner.
Serial Number
This 48-bit value is composed of ROM SN (16-bits) and Fuse SN (32-bits). Together they form a serial
number that is guaranteed to be unique for all devices ever manufactured within the Atmel
CryptoAuthentication family. This value is optionally included in the MAC calculation.
Manufacturing ID
This 24-bit value is composed of ROM MfrID (16-bits) and Fuse MfrID (8-bits). Typically this value is
the same for all chips of a given type. It is always included in the cryptographic computations.
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
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1.4
SHA-256 Computation
This chip performs only one cryptographic calculation – a keyed digest of an input challenge using the SHA-256 algorithm,
documented here:
http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
1.4.1
SHA Computation Example
In order to ensure that there is no ambiguity, the following example vector is provided in addition to the sample vectors in the
NIST document. In this example, all values are listed in hex. For all but the key, bytes are listed in the order that they appear
on the bus – first on the left. Key is listed in the same order, so the 01 at the left of the key string is the first byte passed to
SHA-256.
SHA Computation Example
Key
Challenge
01030507090B0D0F11131517191B1D1F21232527292B2D2F31333537393B3D3F
020406080A0C0E10121416181A1C1E20222426282A2C2E30323436383A3C3E40
Opcode
Mode
Param2
08
40 (include serial number in message)
0000
Fuse MfrID
Fuse S/N
77
8899AABB
ROM MfrID CCDD
ROM SN
EEFF
The 88-bytes over which the digest is calculated are:
0103…3D3F0204…3E4001400000…EEFF
Digest:
7D38245733717A488575B9F794F7BCAFE033A3848D39430DA25141FDEBEAA1C2
A read command executed on Address 0 of the ROM (ROM MfrID, ROM SN) would return CC DD EE FF, with CC being the
first byte on the bus and FF being the last.
Throughout this document, the complete message processed by the SA100S chip is documented. According to the above
specification, this always includes a single bit of ‘1’ pad after the message, followed by a 64-bit value representing the total
number of bits being hashed (less pad and length). If the length is less than 447 (512-64-1) then the necessary number of ‘0’
bits are included between the ‘1’ pad and ‘length’ to stretch the last message block out to 512-bits.
When using standard libraries to calculate the SHA-256 digest, these pad and length bits should probably not be passed to the
library as most standard software implementations of the algorithm add them in automatically.
1.5
Security Features
The AT88SA100S incorporates a number of physical security features designed to protect the key from unauthorized release.
These include an active shield over the entire surface of the internal memory encryption, internal clock generation, glitch
protection, voltage tamper detection and other physical design features.
Both the clock and logic supply voltage are internally generated, preventing any direct attack via the pins on these two signals.
Atmel AT88SA100S [DATASHEET]
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2.
IO Protocol
Communications to and from the AT88SA100S take place over a single asynchronously timed wire uses a pulse count
scheme. The overall communications structure is a hierarchy:
Table 2-1.
2.1
IO Hierarchy
Tokens
Implement a single data bit transmitted on the bus, or the wake-up event
Flags
Comprised of eight tokens (bits) which convey the direction and meaning of the next group of bits (if any)
which may be transmitted
Blocks
of data follow the command and Transmit flags. They incorporate both a byte count and a checksum to ensure
proper data transmission
Packets
of bytes form the core of the block without the count and CRC. They are either the input or output parameters
of an Atmel AT88SA100S chip command or status information from the AT88SA100S chip
IO Tokens
There are a number of IO tokens that may be transmitted along the bus:
Input: (To AT88SA100S)
Wake
Wake AT88SA100S up from sleep (low power) state
Zero
Send a single bit from system to the AT88SA100S with a value of zero
One
Send a single bit from system to the AT88SA100S with a value of one
Output: (From AT88SA100S)
ZeroOut
Send a single bit from the AT88SA100S to the system with a value of zero
OneOut
Send a single bit from the AT88SA100S to the system with a value of one
The waveforms are the same in either direction, however there are some differences in timing based on the expectation that
the host has a very accurate and consistent clock while the AT88SA100S has significant variation in its internal clock
generator due to normal manufacturing and environmental fluctuations.
The bit timings are designed to permit a standard UART running at 230.4 K 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 AT88SA100S. Refer
to applications notes on the Atmel website for more details describing how the UART should be controlled.
Atmel AT88SA100S [DATASHEET]
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2.2
AC Parameters
Figure 2-2. AC Parameters
WAKE
data comm
tWLO
tWHI
LOGIC Ø
tSTART
tZHI
tZLO
tBIT
LOGIC 1
tSTART
NOISE
SUPPRESION
tLIGNORE
3.
tHIGNORE
Absolute Maximum Ratings*
Operating temperature.................... −40°C to +85°C
Storage temperature ................... −65°C to + 150°C
Voltage on any pin
with respect to ground ................− 0.5 to VCC+0.5 V
*NOTICE: 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 of time may affect device reliability.
Atmel AT88SA100S [DATASHEET]
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4.
AC Parameters
Table 4-1.
AC Parameters
Parameter
Symbol
Direction
Wake low
duration
t WLO
To Atmel
CryptoAuthentication
Wake Delay
to Data
Comm.
t WHI
Start pulse
duration
t START
Zero
transmission
high pulse
t ZHI
Zero
transmission
low pulse
t ZLO
Bit time
t BIT
Turn around
delay
t
TURNAROUND
Max
Uni
t
60
-
µs
Signal can be stable in either high or
low levels during extended sleep
intervals.
To Atmel
CryptoAuthentication
2.5
45
ms
Signal should be stable high for this
entire duration. tWHI must not exceed
tTIMEOUT or the chip will transition to
sleep.
To Atmel
CryptoAuthentication
4.1
4.34
4.56
µs
From
CryptoAuthentication
4.6
6.0
8.6
µs
To Atmel
CryptoAuthentication
4.1
4.34
4.56
µs
From Atmel
CryptoAuthentication
4.6
6.0
8.6
µs
To Atmel
CryptoAuthentication
4.1
4.34
4.56
µs
From Atmel
CryptoAuthentication
4.6
6.0
8.6
µs
To Atmel
CryptoAuthentication
37
39
-
µs
From Atmel
CryptoAuthentication
41
54
78
µs
From Atmel
CryptoAuthentication
28
60
95
µs
To Atmel
CryptoAuthentication
15µs
Min
Typ
Notes
If the bit time exceeds t TIMEOUT then the
Atmel CryptoAuthentication will enter
sleep mode and the Wake token must
be resent.
Atmel CryptoAuthentication will initiate
the first low going transition after this
time interval following the end of the
Transmit flag
After Atmel CryptoAuthentication
transmits the last bit of a block, system
must wait this interval before sending
the first bit of a flag
45ms
High side
glitch filter @
active
t HIGNORE_A
To Atmel
CryptoAuthentication
45
ns
Pulses shorter than this in width will be
ignored by the chip, regardless of its
state when active
Low side
glitch filter @
active
t LIGNORE_A
To Atmel
CryptoAuthentication
45
ns
Pulses shorter than this in width will be
ignored by the chip, regardless of its
state when active
Low side
glitch filter @
sleep
t LIGNORE_S
To Atmel
CryptoAuthentication
500
ns
Pulses shorter than this in width will be
ignored by the chip when in sleep mode
Io timeout
t TIMEOUT
To Atmel
CryptoAuthentication
45
65
85
ms
Refer to Section 5.4.1
Watchdog
reset
t WATCHDOG
To Atmel
CryptoAuthentication
3
4
5.7
s
Max. time from Wake until chip is forced
into Sleep mode
See Watchdog Failsafe, Section 5.5
Atmel AT88SA100S [DATASHEET]
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5.
DC Parameters
Table 5-1.
DC Parameters
Parameter
Symbol
Min
Typ
Operating temperature
TA
-40
85
°C
Power supply voltage
VCC
2.7
5.25
V
Fuse burning voltage
VBURN
3.0
5.25
V
Active power supply
current
ICC
6
mA
Sleep Power Supply
Current @ -40 to 55 C
I SLEEP
150
nA
When chip is in sleep mode, VCC = 5.25 V,
Vsig = 0.0 to 0.3 V, or
Vsig = VCC -0.3 V to VCC
Sleep power supply
current @ 85 c
I SLEEP
1
µA
When chip is in sleep mode, VCC = 5.25 V,
Vsig = 0.0 to 0.3 V, or
-
Max
Unit
Notes
Voltage applied to VCC pin. See Section 6.3
Vsig = VCC -0.3 V to Vcc
5.1
Input low voltage @
VCC = 5.25 v
VIL
-0.5
0.75
V
Voltage levels for Wake token when chip is in
sleep mode
Input low voltage @
VCC = 2.7 v
VIL
-0.5
0.5
V
Voltage levels for Wake token when chip is in
sleep mode
Input high voltage @
VCC = 5.25 v
VIH
1.5
5.25
V
Voltage levels for Wake token when chip is in
sleep mode
Input high voltage @
VCC = 2.7 v
VIH
1.25
3.0
V
Voltage levels for Wake token when chip is in
sleep mode
Input low voltage when
active
VIL
-0.5
0.5
V
When chip is in active mode,
VCC = 2.7 – 5.25 V
Input high voltage when
active
VIH
1.2
5.25
V
When chip is in active mode,
VCC = 2.7 – 5.25 V
Output low voltage
VOL
0.4
V
When chip is in active mode,
VCC = 2.7 – 5.25 V
Maximum input voltage
VMAX
5.25
V
IO Flags
The host system is always the bus master, so before any IO transaction, the system must first send an 8-bit flag to the chip to
indicate the IO operation that is to be performed, as follows:
Value
Name
Meaning
0x77
Command
After this flag, the system starts sending a command block to the chip. The first bit of the block can
follow immediately after the last bit of the flag.
0x88
Transmit
After a turn-around delay, the chip will start transmitting the response for a previously transmitted
command block.
0xCC
Sleep
Upon receipt of a sleep flag, the chip will enter a low power mode until the next Wake token is
received.
All other values are reserved and will be ignored.
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5.1.1
Command Timing
After a command flag is transmitted, a command block should be sent to the chip. During parsing of the parameters and
subsequent execution of a properly received command, the chip will be busy and not respond to transitions on the signal pin.
The delays for these operations are listed in the table below:
Table 5-2.
Command Timing (Guaranteed by design; not tested)
Parameter
Symbol
Max
Unit
ParsingDelay
t PARSE
MemoryDelay
Notes
100
µs
Delay to check CRC and parse opcode and parameters before an
error indication will be available
t EXEC_MEM
3
ms
Delay to execute Read, Write and/or SramLock commands
FuseDelay
t EXEC_FUSE
700
µs
Delay to execute BurnFuse command
See Section 6.3 for more details
MacDelay
t EXEC_MAC
30
ms
Delay to execute MAC command
PersonalizeDelay
t PERSON
13
ms
Delay to execute GenPersonalizationKey or LoadSram
In this document, tEXEC is used as shorthand for the delay corresponding to whatever command has been sent to the chip.
5.1.2
Transmit Flag
The Transmit flag is used to turn around the signal so that the AT88SA100S can send data back to the system, depending on
its current state. The bytes that the AT88SA100S returns to the system, depending on its current state as follows:
Table 5-3.
Return Codes
State Description
Error/Status
Description
After Wake, but prior
to first command
0x11
Indication that a proper Wake token has been received by the AT88SA100S.
After successful
command execution
–
Return bytes per “Output Parameters” in Section 6, Commands of this document.
In some cases this is a single byte with a value of 0x00 indicating success. The
Transmit flag can be resent to the AT88SA100S repeatedly if a re-read of the
output is necessary.
Execution error
0x0F
Command was properly received but could not be executed by the AT88SA100S
chip. Changes in the AT88SA100S chip state or the value of the command bits
must happen before it is re-attempted.
After CRC or other
parsing error
0xFF
Command was not properly received by AT88SA100S and should be re-issued
by the system.
The AT88SA100S always transmits complete blocks to the system, so in the above table the status/error bytes result in 4bytes going to the system – count, error, CRC x 2.
After receipt of a command block, the AT88SA100S will parse the command for errors, a process which takes tPARSE (See
Section 5.1.1). After this interval the system can send a transmit token to the AT88SA100S – if there was an error then the
AT88SA100S will respond with an error code. If there is no error then the AT88SA100S internally transitions automatically
from tPARSE to tEXEC and will not respond to any Transmit tokens until both delays are complete.
5.1.3
Sleep Flag
The sleep flag is used to transition the AT88SA100S to the low power state, which causes a complete reset of the
AT88SA100S’ internal command engine and input/output buffer. It can be sent to the AT88SA100S at any time when the
AT88SA100S will accept a flag.
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To achieve the specified ISLEEP, Atmel recommends that the input signal be brought below VIL when the chip is asleep. To
achieve ISLEEP if the sleep state of the input pin is high, the voltage on the input signal should be within 0.3V of VCC to avoid
additional leakage on the input circuit of the chip.
5.1.4
Pause State
The pause state is entered via the PauseLong command and can be exited only when the watchdog timer has expired and the
chip transitions to a sleep state. When in the pause state, the chip ignores all transitions on the signal pin but does not enter a
low power consumption mode.
The pause state provides a mechanism for multiple AT88SA100S chips on the same wire to be selected and to exchange data
with the host microprocessor. The PauseLong command includes an optional address field which is compared to the values in
Fuses 84-87. If the two matches, then the chip enters the pause state, otherwise, it continues to monitor the bus for
subsequent commands. The host would selectively put all but one AT88SA100S in the pause state before executing the MAC
command on the active chip. After the end of the watchdog interval all the chips will have entered the sleep state and the
selection process can be started with a Wake token (which will then be honored by all chips) and selection of a subsequent
chip.
5.2
IO Blocks
Commands are sent to the chip, and responses received from the chip, within a block that is constructed in the following way:
5.3
Byte Number
Name
Meaning
0
Count
Number of bytes to be transferred to the chip in the block, including count, packet and checksum,
so this byte should always have a value of (N+1). The maximum size block is 39 and the
minimum size block is four. Values outside this range will cause unpredictable operation.
1 to (N-2)
Packet
Command, parameters and data, or response
See Section 6 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 and after the last bit of the count and packet have been transmitted
the internal CRC register should have a value that matches that in the block. The first byte
transmitted (N-1) is the least significant byte of the CRC value so the last byte of the block is the
most significant byte of the CRC.
IO Flow
The general IO flow for a MAC command is as follows:
1.
2.
3.
4.
5.
6.
7.
System sends wake token
System sends transmit flag
Receive 0x11 value from the AT88SA100S to verify proper wakeup synchronization
System sends command flag
System sends command block
System waits tPARSE for the AT88SA100S to check for command formation errors
System sends transmit flag. If command format is OK, the AT88SA100S ignores this flag because the computation
engine is busy. If there was an error, the AT88SA100S responds with an error code
8. System waits tEXEC. See Section 5.1.1
9. System sends transmit flag
10. Receive output block from the AT88SA100S, system checks CRC
11. If CRC from the AT88SA100S is incorrect, indicating a transmission error, system resends transmit flag
12. System sends sleep flag to the AT88SA100S
All commands other than MAC have a short execution delay. In these cases the system should omit steps six, seven, and
eight and replace this with a wait of duration tPARSE + tEXEC.
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5.4
Synchronization
Because the communications protocol is half duplex, there is the possibility that the system and the AT88SA100S will fall out
of synchronization with each other. In order to speed recovery, the AT88SA100S implements a timeout that forces the
AT88SA100S to sleep. See Section 5.4.1.
5.4.1
IO Timeout
After a leading transition for any data token has been received, the AT88SA100S will expect the remaining bits of the token to
be properly received by the chip within the tTIMEOUT interval. Failure to send enough bits or the transmission of an illegal token
(a low pulse exceeding tZLO) will cause the chip 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
IO Timeout circuitry is enabled until the last expected data bit is received.
Note:
The timeout counter is reset after every legal token, so the total time to transmit the command may exceed the
tTIMEOUT interval while the time between bits may not
In order to limit the active current if the AT88SA100S is inadvertently awakened, the IO timeout circuitry is also enabled when
the AT88SA100S receives a wake-up. If the first token does not come within the tTIMEOUT interval, then the AT88SA100S will go
back to the sleep mode without performing any operations.
The IO timeout circuitry is disabled when the chip is busy executing a command.
5.4.2
Synchronization Procedures
When the system and the AT88SA100S fall out of synchronization, the system will ultimately end up sending a Transmit flag
which will not generate a response from the AT88SA100S. The system should implement its own timeout which waits for
tTIMEOUT during which time the AT88SA100S should go to sleep automatically. At this point, the system should send a Wake
token and after tWLO + tWHI, a Transmit token. The 0x11 status indicates that the resynchronization was successful.
It may be possible that the system does not get the 0x11 code from the AT88SA100S for one of the following reasons:
1.
2.
3.
5.5
The system did not wait a full tTIMEOUT delay with the IO signal idle in which case the AT88SA100S may have
interpreted the Wake token and Transmit flag as a data bits. Recommended resolution is to wait twice the tTIMEOUT
delay and re-issue the Wake token.
The AT88SA100S went into the sleep mode for some reason while the system was transmitting data. In this case,
the AT88SA100S will interpret the next data bit as a Wake token, but ignore some of the subsequently transmitted
bits during its wake-up delay. If any bytes are transmitted after the wake-up delay, they may be interpreted as a legal
flag, though the following bytes would not be interpreted as a legal command due to an incorrect count or the lack of
a correct CRC. Recommended resolution is to wait the tTIMEOUT delay and re-issue the Wake token.
There is some internal error condition within the AT88SA100S which will be automatically reset after a tWATCHDOG
interval, see below. There is no way to externally reset the AT88SA100S – the system should leave the IO pin idle
for this interval and issue the Wake token.
Watchdog Failsafe
After the Wake token has been received by the AT88SA100S, a watchdog counter is started within the chip. After tWATCHDOG,
the chip will enter sleep mode, regardless of whether it is in the middle of execution of a command and/or whether some IO
transmission is in progress. There is no way to reset the counter other than to put the chip to sleep and wake it up again.
This is implemented as a fail-safe so that no matter what happens on either the system side or inside the various state
machines of the AT88SA100S including any IO synchronization issue, power consumption will fall to the low sleep level
automatically.
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
11
5.6
Byte and Bit Ordering
The AT88SA100S is a little-endian chip:
•
•
•
6.
All multi-byte aggregate elements within this spec are treated as arrays of bytes and are processed in the order
received
Data is transferred to/from the AT88SA100S least significant bit first on the bus
In this document, the most significant bit appears towards the left hand side of the page
Commands
The command packet is broken down in the following way:
Byte
Name
Meaning
0
Opcode
The command code
1
Param1
The first parameter – always present
2-3
Param2
The second parameter – always present
4+
Data
Optional remaining input data
If a command fails because the CRC within the block is incorrect, the opcode is invalid or one of the parameters is illegal, then
immediately after tPARSE the system will be able to retrieve an error response block containing a single byte packet. The value
of that byte will be either 0x0F or 0xFF depending on the source of the error. See Section 5.1.2.
If a command is received successfully then after the appropriate execution delay the system will be able to retrieve the output
block as described in the individual command descriptions below.
In the individual command description tables below, the size column describes the number of bytes in the parameter
documented in each particular row. The total size of the block for each of the commands is fixed, though that value is different
for each command. If the block size for a particular command is incorrect, the chip will not attempt the command execution
and return an error.
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
12
6.1
MAC
Computes a SHA-256 digest of the key, challenge and other fixed information on the chip to generate an output response. If
MemValid is not set, indicating that no valid key is stored in the SRAM, then this command will return an error. The hashed
message includes the following bytes, concatenated in this order:
256-bits
Key (Stored in Sram)
256-bits
Challenge
8-bits
Opcode (always 0x08)
8-bits
Mode input
16-bits
Param2 input
88-bits
All zeros
8-bits
Fuse MfrID (Fuse[88-95])
32-bits
Fuse SN (Fuse[96-127]) or zeros
16-bits
ROM MfrID
16-bits
ROM SN or zeros
1-bit
1’s – SHA-256 padding
255-bits
0’s – SHA-256 padding
64-bits
Table 6-1.
Length (704) per SHA-256
Input Parameters
Name
Size
Opcode
MAC
1
0x08
Param1
Mode
1
See Table 6-6
Param2
Zero
2
Must be 0x0000
Data
Challenge
32
Input portion of message to be digested
Table 6-2.
Name
Response
Table 6-3.
Notes
Output Parameters
Size
32
Notes
SHA-256 digest
Mode Encoding
Bit
Notes
6
If set, then the four bytes of Fuse SN and the two bytes of ROM SN will be included in the message,
otherwise these bits will be set to zero in the message
0-5, 7
Ignored, must be all zero
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
13
6.2
Read
Reads four bytes from Fuse, ROM or MemValid. Any attempt to present the chip with an illegal Fuse address will result in an
error return.
Table 6-4.
Input Parameters
Name
Size
Opcode
READ
1
0x02
Param1
Mode
1
Fuse, ROM or MemValid. See to Table 12
Param2
Address
2
Which 4-bytes within array. Bits 2-15 are ignored by the chip and should be zeros
Data
–
0
Table 6-5.
Name
Notes
Output Parameters
Size
Contents
4
Table 6-6.
Mode Encoding
Notes
The contents of the specified memory location
Name
Value
Notes
ROM
0x00
Reads four bytes from the ROM. Bit 1 of the address parameter must be zero
Fuse
0x01
Reads the value of 32-fuses
MemValid
0x03
Returns four bytes. The LSB of the first byte indicates whether or not the contents
of the SRAM are valid. All other bits in all bytes have a value of zero. The address
parameter is ignored
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
14
6.3
BurnFuse
Burns one of the 88 user accessible fuse bits.
The values in fuses #88-127 are reserved for Fuse MfrID and Fuse SN and cannot be blown via this command. All addresses
above 0x57 (87) will result in an error.
Fuses, with the exception of those initialized by Atmel, have a value of one on shipment from the Atmel factory and transition
to a zero when they are burned.
Fuse bits zero through seven of the fuse array are word lock bits. Burning one of these has the effect of locking the
corresponding 16-bit word within Fuse. Bit 0 locks fuses 0-15, bit 1 locks fuses 16-31 and so on. If bit 0 is burned, then the
value of the lock bits can no longer be changed. The values of lock bits six and seven are ignored by the chip.
The power supply pin must meet the VBURN specification during the entire BurnFuse command in order to burn fuses reliably. If
Vcc is greater than or equal to 3.7 V, then the BurnTime parameter should be set to 0x00 and the internal burn time will be
250µs. If Vcc is less than 3.7 V but greater than VBURN then the BurnTime parameter should be set to 0xFFFF and the internal
burn time will be up to 262ms. The chip does not internally check the supply voltage level.
There is a very small interval during tEXEC_BURN when the fuse element is actually being burned. During this interval, the power
supply must not be removed and the watchdog timer must not be allowed to expire or the fuse may end up in a state where it
reads as un-burned but cannot be burned.
Table 6-7.
Input Parameters
Name
Size
Notes
Opcode
BURNFUSE
1
0x04
Param1
FuseNum
1
Which bit within fuse array, minimum value is 0, and maximum value is 87
Param2
BurnTime
2
Must be 0x0000 if Vcc >=3.7 V; must be 0xFFFF otherwise
Data
–
0
Table 6-8.
Name
Success
Output Parameters
Size
1
Notes
Upon successful completion, a value of 0 will be returned by the Atmel AT88SA100S
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
15
6.4
GenPersonalizationKey
This command generates a decryption digest that will be used by the subsequent command (LoadSram) to decrypt the key
value that is to be written into the SRAM. This command must be run immediately prior to LoadSram within the same
watchdog cycle.
This command loads a transport key from an internal secure storage location and then uses that key along with an input seed
to generate a decryption digest using SHA-256. Neither the transport key nor the decryption digest can be read from the chip.
Upon completion, an internal bit is set indicating that the decryption digest has been generated and is ready to use by
LoadSram. This bit is cleared (and the digest lost) when the watchdog timer expires, the chip goes to sleep or the power is
cycled.
Table 6-9.
Input Parameters
Name
Size
Notes
Opcode
GenPers
1
0x20
Param1
Zero
1
Must be 0x00
Param2
KeyID
2
Identification number of the personalization key to be loaded
Data
Seed
16
Seed for digest generation. The least significant bit of the last byte is ignored
Table 6-10. Output Parameter
Name
Size
Success
1
Notes
Upon successful execution, a value of 0 will be returned by the AT88SA100S chip
The SHA-256 message body used to create the decryption digest which is internally stored in the chip consists of the following
512-bits:
256-bits
64-bits
127-bits
1-bit
64-bits
Stored Key[KeyID]
All ones
Input seed
‘1’ pad
length of message in bits, fixed at 447
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
16
6.5
LoadSram
Writes 256-bits into the battery backed SRAM and locks this memory against further modification. The value in the battery
backed SRAM cannot be read, it must be verified via the MAC command. If the secret value in the SRAM is already valid then
this command will fail with an error response. The only way to unlock the SRAM is to remove power from the AT88SA100S.
The input data (secret key) is always decrypted using the decryption digest previously generated by GenPersonalizationKey
prior to being written into the battery backed SRAM.
Note:
Both the GenPersonalizationKey and LoadSram commands must be run consecutively within a single Wake
cycle prior to the expiration of the watchdog timer. If any command is inserted between these two operations
then LoadSram will fail.
Table 6-11. Input Parameters
Name
Size
Notes
Opcode
LOADSRAM
1
0x10
Param1
Zero1
1
Must be 0x00
Param2
Zero2
2
Must be 0x0000
Data
Key
32
Encrypted value to be written into the SRAM
Table 6-12. Output Parameter
Name
Success
Size
1
Notes
Upon successful execution, a value of 0 will be returned by the AT88SA100S chip
The AT88SA100S chip executes the following sequence on receipt of this command.
1.
2.
3.
4.
If the internal flag (indicating that a personalization key has been loaded) is not set, then return error. If the
MemValid flag is set, return error
Successively XOR each byte in the data (secret key) parameter with the corresponding byte from the personalization
key generated by GenPersonalizationKey
Transfer the resulting bytes to the battery backed SRAM
Set MemValid (internal flag) to one
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
17
6.6
PauseLong
Forces the chip into the pause state until the watchdog timer expires, after which it will automatically enter into the sleep state.
During execution of this command the chip will ignore all activity on the IO signal. This command is used to prevent bus
conflicts in a system that also includes the CryptoAuthentication host chip sharing the same signal wire.
Table 6-13. Input Parameters
Name
Size
Notes
Opode
PAUSELONG
1
0x01
Param1
Selector
1
Which chip to put into the pause state, 0x00 for all chips
Param2
Zero
2
Must be 0x0000
Data
Ignored
0
Table 6-14. Output Parameter
Name
Success
Size
1
Notes
If the command indicates that some other chip should go into the pause state, a value of zero will be
returned by this AT88SA100S chip. If this chip goes into the pause state no value will be returned.
The selector parameter provides a mechanism to select which AT88SA100S will pause if there are multiple devices on the
bus:
•
•
If the selector parameter is 0x00, then every chip receiving this command will go into the pause state and no chip will
return a success code.
If any of the bits of the selector parameter are set, then the chip will read the values of Fuse[84-87] and go to sleep
only if those fuse values match the least significant four bits of the selector parameter. If the chip does not go into
the pause state, it returns an error code of 0x0F. Otherwise, it goes into the pause state and never returns any code.
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
18
7.
Pinout
Table 7-1.
Pin Definitions
SOIC/TSSOP
SOT-23
Name
Description
5
1
Signal
IO channel to the system, open drain output. It is expected that an external pull-up
resistor will be provided to pull this signal up to VCC for proper communications.
When the chip is not in use this pin can be pulled to either VCC or GND.
8
2
VCC
Power supply, 2.7 – 5.25 V. This pin should be bypassed with a high quality 0.1µF
capacitor close to this pin with a short trace to GND
Additional applications information at www.atmel.com
4
3
GND
Connect to system ground
1,2,3,6,7
--
NC
Not connected
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
19
Package Drawings
3TS1 – Shrink SOT
3
GND
E1
CL
E
Signal
SDA
VCC
1
L1
8.
2
e1
End View
Top View
b
A2
SEATING
PLANE
e
A
A1
D
Side View
Notes:
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 0.08
mm and 0.15mm from the lead tip.
This drawing is for general information only. Refer to JEDEC Drawing
TO-236, Variation AB for additional information.
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL
MIN
A
A1
A2
D
E
E1
L1
e1
b
0.89
0.01
0.88
2.80
2.10
1.20
MAX
NOM
2.90
1.30
0.54 REF
1.90 BSC
0.30
-
1.12
0.10
1.02
3.04
2.64
1.40
0.50
NOTE
1,2
1,2
3
12/11/09
R
Package Drawing Contact:
[email protected]
TITLE
GPC
DRAWING NO.
REV.
3TS1, 3-lead, 1.30mm Body, Plastic Thin
Shrink Small Outline Package (Shrink SOT)
TBG
3TS1
B
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
20
8X – 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
Side View
Notes:
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
E1
4.30
4.40
4.50
3, 5
b
0.19
–
0.30
4
SYMBOL
D
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 0.15mm (0.006in) per side.
3. Dimension E1 does not include inter-lead Flash or
protrusions. Inter-lead Flash and protrusions shall not exceed
0.25mm (0.010in) 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 0.07mm.
5. Dimension D and E1 to be determined at Datum Plane H.
E
2, 5
6.40 BSC
e
L
NOTE
0.65 BSC
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 AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
REV.
D
21
8S1 – JEDEC 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 AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
22
9.
Ordering Information
Atmel AT88SA100S Ordering Information
10.
Atmel Ordering Code
Package Type
Temperature Range
AT88SA100S-SH-CZ-T
SOIC, Tape and Reel
-40 °C to 85 °C
AT88SA100S -TH-CZ-T
TSSOP, Tape and Reel
-40 °C to 85 °C
AT88SA100S -TSU-T
3LD SOT23, Tape and Reel
-40 °C to 85 °C
Revision History
Doc. Rev.
Date
Comments
8558F
09/2011
Correct references and sections numbers
Section 5.1.3, Sleep Flag, change “ within 0.5V of VCC” to “within 0.3V of VCC”
8558E
08/2010
Update IO timeout description
8558D
06/2010
Update to Table 3: AC Parameters
8558C
05/2010
Expansion of IO Timeout specification
8558B
04/2010
Add TSSOP and SOIC packages
8558A
03/2009
Initial document release
Atmel AT88SA100S [DATASHEET]
8558F−CRYPTO−9/11
23
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© 2011 Atmel Corporation. All rights reserved. / Rev.: 8558F−CRYPTO−9/11
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