at88sc018 ATMEL Corporation, at88sc018 Datasheet - Page 23

• Manufacturer Part Number: at88sc018
• Description: Cryptocompanion? Chip For Cryptomemory And Cryptorf
• Manufacturer: ATMEL Corporation

3.15. ReadMemory
3.16.
5277C–CryptoCompanion–9/09
Table 42.
The AT88SC018 will compute the SHA-1 hash of (Address, EncKey, Nonce). The first 16 bytes of the resulting digest
will be used as an XOR key to decrypt the incoming data, which will then be written to the specified page in EEPROM.
Reads the contents of the EEPROM from the specified address and those following it up to the end of R/W EEPROM.
Once locked, only the read-only and read/write spaces can be read. Addresses 0 through 0x2F may never be read.
Up to 16 bytes may be accessed within a single read operation.
This command can be run prior to locking of the memory only if the least two significant bits of the lock byte have a
value of 0.
Table 43.
Table 44.
ReadMemoryDigest
Reads the specified 32 byte block from the EEPROM, computes the SHA-1 digest of that block and returns that digest
to the user. This command provides a mechanism of verifying that the personalization of the chip completed correctly
before the one-time lock has been run.
Note:
This command cannot be run after the AT88SC018 has been locked or if the unlocked state is Lock[1:0] == 00. When it
can be run it can access all locations within the EEPROM.
Table 45.
Table 46.
Address
Count
Data
Address
Data
Name
Name
Name
Name
Name
Specifying an address of 0 requires that the verifier know the value of EncKey.
Outputs
Inputs
Outputs
Inputs
Outputs
Size
Size
Size
Size
Size
20
⎯
2
1
2
Address in EEPROM of the first byte of data to be read. The most significant 7 bits are
ignored.
If 0, read 1 byte… if 0x0F, read 16 bytes. The upper 4 bits are ignored.
Clear text bytes, maximum of 16
Address of the 32 byte block within EEPROM which should be read. The least significant
5 and most significant 7 bits are ignored.
Digest of the selected 32 byte block of the EEPROM
Description
Description
Description
Description
Description
CryptoCompanion Chip
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