Rainbow-electronics AT88SA100S Manual de usuario descargar pdf (Pagina 13)

AT88SA100S [ Preliminary]

8558A–SMEM–03/09

4.1. 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 0x01)

8 bits Mode input

16 bits Param2 input

88 bits All 0’s

8 bits MfrID Fuse[88-95]

32 bits SerialNum Fuse[96-127], or 0’s

16 bits ROM MfrID

16 bits ROM SN), or 0’s

1 bit 1’s – SHA-256 padding

255 bits 0’s – SHA-256 padding

64 bits Length (704) per SHA-256

Table 7. Input Parameters

Name Size Notes

Opcode MAC 1 0x08

Param2 Zero 2 Must be 0x00 00

Data Challenge 32 Input portion of message to be digested

Table 8. Output Parameters

Name Size Notes

Response 32 SHA-256 digest

Table 9. Mode Encoding

Bit Notes

6 If set, then the 4 bytes of Serial Number Fuses and the two bytes of ROM SN will be included in the

message, otherwise these bits will be set to 0 in the message.

0-5, 7 Ignored, must be all 0.

1 2 ... 8 9 10 11 12 13 14 15 16 17 18 19 20 21

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Rainbow-electronics AT88SA100S Manual de usuario Pagina 13