Hardware/AES engine
| AES engine | |
| Access | |
|---|---|
| Espresso | None |
| Starbuck | Full |
| Registers | |
| Base | 0x0d020000, 0x0d180000 |
| Length | 0x14 |
| Access size | 32 bits |
| Byte order | Big Endian |
| IRQs | |
| Espresso | None |
| Latte | 2 |
The Latte's AES Engine encrypts/decrypts 16-byte blocks using AES-128 in Cipher Block Chaining mode.
There are also traces of code inside IOS-CRYPTO that suggest the existence of a second engine named AESS, probably only available in evaluation/debug units.
Register List
| AES Engine | |||
|---|---|---|---|
| Address | Bits | Name | Description |
| 0x0d020000 | 32 | AES_CTRL | AES Control and Status |
| 0x0d020004 | 32 | AES_SRC | Source memory address |
| 0x0d020008 | 32 | AES_DEST | Destination memory address |
| 0x0d02000c | 32 | AES_KEY | Key FIFO |
| 0x0d020010 | 32 | AES_IV | IV FIFO |
| AESS Engine | |||
|---|---|---|---|
| Address | Bits | Name | Description |
| 0x0d180000 | 32 | AESS_CTRL | AESS Control and Status |
| 0x0d180004 | 32 | AESS_SRC | Source memory address |
| 0x0d180008 | 32 | AESS_DEST | Destination memory address |
| 0x0d18000c | 32 | AESS_KEY | Key FIFO |
| 0x0d180010 | 32 | AESS_IV | IV FIFO |
Register Details
| AES_CTRL (0x0d020000) | ||||||||||||||||
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| Access | R/W | R/W | R/W | R/W | R/W | U | ||||||||||
| Field | EXEC | IRQ | ERR | ENA | DEC | |||||||||||
| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| Access | U | W | W | |||||||||||||
| Field | IV | BLOCKS | ||||||||||||||
This register controls the state of the AES engine.
| Field | Description |
| EXEC | Write 1: initiate AES command Write 0: reset AES engine Read: AES engine busy |
| IRQ | Set to enable IRQ generation when command is complete |
| ERR | If set, AES error occurred (?)[check] |
| ENA | Enable en/decryption. If clear, the data is copied straight from source to destination without change (useful as a DMA copy engine?). |
| DEC | Set to decrypt, clear to encrypt |
| IV | If set, chain from last command (continue CBC mode). If clear, use the supplied IV. |
| DATALEN | Number of 16-byte blocks to process, minus one. 0 means one block. |
| AES_SRC (0x0d020004) | ||
| 314 | 30 | |
| Access | R/W | U |
This register contains the DMA address of the source data. The same buffer can be used for source and destination. The address must be 16-byte aligned. The engine updates this register as it processes the blocks.
| AES_DEST (0x0d020008) | ||
| 314 | 30 | |
| Access | R/W | U |
This register contains the DMA address of the destination data. The same buffer can be used for source and destination. The address must be 16-byte aligned. The engine updates this register as it processes the blocks.
| AES_KEY (0x0d02000c) | |
| 310 | |
| Access | W |
This register implements a FIFO that accepts the AES key. A sequence of four 32-bit writes will set the AES key (starting with the leftmost 32-bit word).
| AES_IV (0x0d020010) | |
| 310 | |
| Access | W |
This register implements a FIFO that accepts the AES IV. A sequence of four 32-bit writes will set the AES IV (starting with the leftmost 32-bit word). Clear the IV bit in the AES_CTRL register to restart the CBC encryption using this IV instead of using the last encrypted block.