GD32W51x User Manual
932
Figure 27-7. DES/TDES CBC decryption
SWAP
CAU_DI
DATAM
DEA, decrypt
DEA, decrypt
DEA, encrypt
KEY3
KEY2
KEY1
SWAP
CAU_DO
Ciphertext
Plaintext
CAU_IV0(H/L)
+
27.4.2.
AES cryptographic acceleration processor
The AES cryptographic acceleration processor consists of three components, including the
AES algorithm (AEA), multiple keys and the initialization vectors or Nonce.
Three lengths of AES keys are supported: 128, 192 and 256 bits, and different initialization
vectors or nonce are used depends on the operation mode.
The AES key is used as [KEY3 KEY2] when the key size is configured as 128, [KEY3 KEY2
KEY1] when the key size is configured as 192 and [KEY3 KEY2 KEY1 KEY0] when the key
size is configured as 256.
The thorough explanation of the key used in the AES is provided in FIPS PUB 197 (November
26, 2001), and the explanation process is omitted in this manual.
AES-ECB mode encryption
The 128-bit input plaintext is first obtained after data swapping according to the data type.
The input data block is read in the AEA and encrypted using the 128, 192 or 256 -bit key. The
output after above process is then swapped back according to the data type again, and a
128-bit ciphertext is produced and stored in the out FIFO. The procedure of AES ECB mode
encryption is illustrated in
Figure 27-8. AES ECB encryption
.