RSA Registers

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Registers

NAME PHYSICAL ADDRESS WIDTH
REG_RSACNT 0x1000B000 0x04
REG_RSASLOT0 0x1000B100 0x10
REG_RSASLOT1 0x1000B110 0x10
REG_RSASLOT2 0x1000B120 0x10
REG_RSASLOT3 0x1000B130 0x10
REG_RSAKEY 0x1000B400 0x100
REG_RSATXT 0x1000B800 0x100

REG_RSACNT

Bit Description
0 Busy
1 Keyslot select related?
4-7 Keyslot
8-9 Should be set to 0x3 before accessing REG_RSAMSG

REG_RSASLOT

Start Width Description
0x0 0x4 REG_RSASLOTCNT
0x4 0x4 ?
0x8 0x4 ?
0xC 0x4 ?

REG_RSASLOTCNT

Bits Description
0 Key status (1=Key has been set, 0=Key has not been set yet)
31-1 ?

REG_RSAKEY

The RSA public key for the selected keyslot can be written here. When writing the RSA key, the key is copied to 0x1000B500-RSA_bytesize, length RSA_bytesize. The engine determines the RSA byte-size by checking where the first word of the key was written. The engine only supports RSA-2048 and below.

REG_RSATXT

The RSA signature can be written here, and the data read from here is the message. When writing the RSA signature, the signature must be prepended with zeroes until it is a multiple of 8 bytes, and the end of the signature must align with the end of the register area.

The PKCS message padding must be manually checked by software, as hardware will only do raw RSA operations.

Keyslots usage

Keyslot Description
0 Arbitrary
1 CXI access desc (following the exheader)
2-3 Unused