Atmel AT88SA10HS [DATASHEET] 2
8595H−CRYPTO−9/2012
1. Introduction
The Atmel CryptoAuthentication family of chips is the first cost-effective authentication devices to implement the
SHA-256 hash algorithm, which is part of the latest set of recommended algorithms by the US Government. The 256-bit key
space renders any exhaustive attacks impossible.
The AT88SA10HS host version of CryptoAuthentication chips is capable of validating the response coming from the SHA-256
engine within an authentic CryptoAuthentication client (SA100S or SA102S), even if that response includes within the
computation the serial number of the client. For detailed information on the cryptographic protocols, algorithm test values and
usage models. See “Atmel AT88SA100S” and “Atmel AT88SA102S” datasheets, along with the application notes dedicated to
this product family.
The host CryptoAuthentication performs three separate operations (named HOST0, HOST1, and HOST2) to implement this
validation. The AT88SA10HS chip takes both the challenge and response as inputs and returns a single Boolean indicating
whether or not the response is valid, in order to prevent the host chip from being used to model a valid client.
The host system is responsible for generating the random challenge that is sent to both the client and host
CryptoAuthentication devices as AT88SA10HS does not include a random number generator.
Note: The chip 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 5.5 for more details.
1.1 Memory Resources
Fuse Block of 128-fuse bits that can be written through the one wire interface. Fuse[87] has special
meanings. See Section 1.2 for more details. Fuses[88:95] are part of the manufacturer ID value fixed by
Atmel. Fuses[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. The following three
fields are stored in the ROM:
ROM MfrID 2-bytes of ROM that specifies part of the manufacturing ID code. This Atmel assigned value is always
the same for all chips of a particular model number. For the AT88SA10HS, 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 2-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 MaskSN is read by accessing
ROM bytes 2 and 3 of Address 0. The serial number can always be read by the system but is never
included in the message digested by the HOST command.
RevNum 4-bytes of ROM that are used by Atmel to identify the model mask and/or design revision of the
AT88SA10HS chip. These bytes can be freely read as the four bytes returned by ROM Address 1;
however, system code should not depend on this value as it may change from time to time.
