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_RSAEXPFIFO | 0x1000B200 | 0x04 |
| REG_RSAMOD | 0x1000B400 | 0x100 |
| REG_RSATXT | 0x1000B800 | 0x100 |
REG_RSACNT
| Bit | Description |
|---|---|
| 0 | Start (1=Enable/Busy, 0=Idle) |
| 1 | Encrypt/Decrypt |
| 4-7 | Keyslot select |
| 8-9 | Should be set to 0x3 before accessing REG_RSATXT and REG_RSAKEY |
REG_RSASLOT
| Start | Width | Description |
|---|---|---|
| 0x0 | 0x4 | REG_RSASLOTCNT |
| 0x4 | 0x4 | REG_RSASLOTSIZE |
| 0x8 | 0x4 | ? |
| 0xC | 0x4 | ? |
REG_RSASLOTCNT
| Bits | Description |
|---|---|
| 0 | Key status (1=Key has been set, 0=Key has not been set yet) |
| 1 | Key write-protect |
| 31-2 | ? |
REG_RSASLOTSIZE
This contains the RSA size for this slot, in words. Normally this is 0x40 for RSA-2048.
REG_RSAEXPFIFO
The 0x100-byte exponent is written to this write-only FIFO.
REG_RSAKEY
The RSA public key for the selected keyslot can be written here. When writing the RSA key, the key must align with the end of the register area.
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 |