GD32W51x User Manual
928
Figure 27-3. CAU diagram
AHB BUS
Input FIFO
8*32
CAU_DI
Output FIFO
8*32
CAU_DO
Data swapping
Data swapping
Config
Cryptographic acceleration core (DES/TDES/AES)
CAU_CTL
CAU_STAT0
CAU_
DMAEN
CAU_
INTEN
CAU_
INTF
CAU_
STAT1
CAU_
KEY0..3
CAU_
IV0..1
27.4.1.
DES/TDES cryptographic acceleration processor
The DES/TDES cryptographic acceleration processor contains the DES algorithm (DEA),
cryptographic keys (DES algorithm needs 1 key and TDES algorithm needs 3 keys), and
initialization vectors in CBC mode.
DES/TDES key
[KEY1] is used in DES and [KEY3 KEY2 KEY1] are used in TDES respectively.
When TDES algorithm is configured, three different keying options are allowed:
1. Three same keys
The three keys KEY3, KEY2 and KEY1 are completely equal, which means KEY3 = KEY2 =
KEY1. FIPS PUB 46-3
– 1999 (and ANSI X9.52 -1998) refers to this option. It is easy to
understand that this mode is equivalent to DES.
2. Two different keys
In this option, KEY2 is different from KEY1, and KEY3 is equal to KEY1, which means, KEY1
and KEY2 are independent while KEY3 = KEY1. FIPS PUB 46-3
– 1999 (and ANSI X9.52 –
1998) refers to this option.
3. Three different keys
In this option, KEY1, KEY2 and KEY3 are completely independent. FIPS PUB 46-3 -1999
(and ANSI X9.52
– 1998) refers to this option.
More information of the thorough explanation of the key used in the DES/TDES please refer
to FIPS PUB 46-3 (and ANSI X9.52 -1998), and the explanation process is omitted in this
manual.