Aes Key Registers; Aes Initialization Vector Registers; Aes Dma Interface; Table 129. Key Endianness In Aes_Keyrx Registers (128- Or 256-Bit Key Length) - ST STM32F423 Reference Manual

AES hardware accelerator (AES)
24.4.14

AES key registers

The AES_KEYRx registers store the encryption or decryption key bitfield KEY[127:0] or
KEY[255:0]. The data to write to or to read from each register is organized in the memory in
little-endian order, that is, with most significant byte on the highest address.
The key is spread over the eight registers as shown in

Table 129. Key endianness in AES_KEYRx registers (128- or 256-bit key length)

AES_KEYR7 AES_KEYR6
[31:0] [31:0]
- -
KEY[255:224] KEY[223:192] KEY[191:160] KEY[159:128]
The key for encryption or decryption may be written into these registers when the AES
peripheral is disabled.
The key registers are not affected by the data swapping controlled by DATATYPE[1:0]
bitfield of the AES_CR register.
24.4.15

AES initialization vector registers

The four AES_IVRx registers keep the initialization vector input bitfield IVI[127:0]. The data
to write to or to read from each register is organized in the memory in little-endian order, that
is, with most significant byte on the highest address. The registers are also ordered from
lowest address (AES_IVR0) to highest address (AES_IVR3).
The signification of data in the bitfield depends on the chaining mode selected. When used,
the bitfield is updated upon each computation cycle of the AES core.
Write operations to the AES_IVRx registers when the AES peripheral is enabled have no
effect to the register contents. For modifying the contents of the AES_IVRx registers, the EN
bit of the AES_CR register must first be cleared.
Reading the AES_IVRx registers returns the latest counter value (useful for managing
suspend mode).
The AES_IVRx registers are not affected by the data swapping feature controlled by the
DATATYPE[1:0] bitfield of the CRYP_CR register.
24.4.16

AES DMA interface

The AES peripheral provides an interface to connect to the DMA (direct memory access)
controller. The DMA operation is controlled through the AES_CR register.
Data input using DMA
Setting the DMAINEN bit of the AES_CR register enables DMA writing into AES. The AES
peripheral then initiates a DMA request during the input phase each time it requires a word
to be written to the AES_DINR register. It asserts four DMA requests to transfer one 128-bit
(four-word) input data block from memory, as shown in
See Table 130
726/1324
AES_KEYR5 AES_KEYR4
[31:0] [31:0]
- -
for recommended DMA configuration.
RM0430 Rev 8
Table 129.
AES_KEYR3 AES_KEYR2
[31:0] [31:0]
KEY[127:96] KEY[95:64]
KEY[127:96] KEY[95:64]
Figure
RM0430
AES_KEYR1 AES_KEYR0
[31:0] [31:0]
KEY[63:32] KEY[31:0]
KEY[63:32] KEY[31:0]
251.