at88sa102s ATMEL Corporation, at88sa102s Datasheet - Page 2

• Manufacturer Part Number: at88sa102s
• Description: Cryptoauthentication
• Manufacturer: ATMEL Corporation

1.1.
1.2.
1.3.
2
The chip includes 128 single bit one time programmable fuses that can be used for personalization, status or
consumption logging. Atmel programs 40 of these bits prior to the chip leaving the factory, leaving 88 for user
purposes. Refer to
Note:
Usage
There are many different ways in which CryptoAuthentication can add an authentication capability to a system. For
more information, refer to the “CryptoAuthentication Usage Examples” Applications Note.
In general, however, all these security models usually employ one of two general key management strategies:
• Fixed challenge response number pair stored in the host. In this case, the host sends its particular challenge and
• Host computes the response that should be provided for a particular client against a random challenge and/or
Memory Resources
Fuse
ROM
Fuse Map
The AT88SA102S 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 manufacturer ID and serial number bits initialized by Atmel, have a value of 1
when shipped from the Atmel factory and transition to a 0 when they are burned. Bits 0-63 can never be read, while bits
64-128 can always be read.
AT88SA102S [Preliminary]
only an authentic CryptoAuthentication can generate the correct response. Since no secret is stored on the host,
there is no security cost on the host. Depending on the particulars of the system, each host may have a different
challenge response pair and/or each client may have the same key.
include the client ID# in the calculation. In this case, the host needs to have the capability to securely store the secret
from which diversified response will be computed. One way to do this is to use a CryptoAuthentication host chip.
Since each client is unique, the host can maintain a dynamic black list of clients that have been found to be
fraudulent.
ROM MfrID
ROM SN
RevNum
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 command execution or IO transfers that may be happening at the time the
timer expires. System programming must take this into consideration. Refer to
Block of 128 fuse bits that can be written through the 1 wire interface. Fuse[0], Fuse[1] and Fuse[87]
have special meanings, refer to
manufacturing ID value fixed by Atmel. Fuse[96:127] are programmed by Atmel with a serial number
that (in combination with ROM SN) is guaranteed to be unique and which includes lot/wafer info.
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.
Section 1.3
2 bytes of ROM that, when combined with Fuse[88:95] specifies the 24 bit manufacturing ID
code. This value is assigned by Atmel and is always the same for all chips of a particular model
number. For the AT88SA102S, this value is 0xFF FF FF. The MfrID can be read by accessing
ROM bytes 0 & 1 of Address 0. The 24 bit MfrID value can always be read by the system and is
always included in the message digested by the MAC command.
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 ROM SN is read by
accessing ROM bytes 2 & 3 of Address 0. The complete serial number is extended with an
additional 32 fuses to form the 48 bit serial number. The serial number can always be read by
the system and is optionally included in the message digested by the MAC command.
4 bytes of ROM that are used by Atmel to identify the model mask and/or design revision of the
AT88SA102S chip. These bytes can be freely read as the four bytes returned ROM address 1,
however system code should not depend on this value as it may change from time to time.
for more information.
Section 1.3
for more details. Fuse[88:95] are part of the
Section 3.5
for more details.
8584A–SMEM–03/09