38.8.1 Control A

Name: CTRLA
Offset: 0x00
Reset: 0x00000000
Property: PAC Write-Protection, Enable-protected

Bit 3130292827262524 
          
Access  
Reset  
Bit 2322212019181716 
     CTYPE[3:0] 
Access R/WR/WR/WR/W 
Reset 0000 
Bit 15141312111098 
  XORKEYKEYGENLODSTARTMODECIPHERKEYSIZE[1:0] 
Access R/WR/WR/WR/WR/WR/WR/W 
Reset 0000000 
Bit 76543210 
 CFBS[2:0]AESMODE[2:0]ENABLESWRST 
Access R/WR/WR/WR/WR/WR/WR/WR/W 
Reset 00000000 

Bits 19:16 – CTYPE[3:0] Countermeasure type

ValueNameDescription
XXX0 CTYPE1 disabled Countermeasure1 disabled
XXX1 CTYPE1 enabled Countermeasure1 enabled
XX0X CTYPE2 disabled Countermeasure2 disabled
XX1X CTYPE2 enabled Countermeasure2 enabled
X0XX CTYPE3 disabled Countermeasure3 disabled
X1XX CTYPE3 enabled Countermeasure3 enabled
0XXX CTYPE4 disabled Countermeasure4 disabled
1XXX CTYPE4 enabled Countermeasure4 enabled

Bit 14 – XORKEY XOR Key

ValueDescription
0 No effect
1 The user keyword gets XORed with the previous keyword register content.

Bit 13 – KEYGEN Key Generation

ValueDescription
0 No effect
1 Start Computation of the last NK words of the expanded key

Bit 12 – LOD Last Output Data Mode

ValueDescription
0 No effect
1 Start encryption in Last Output Data mode

Bit 11 – STARTMODE Start Mode Select

ValueNameDescription
0 Manual Mode Start Encryption / Decryption in Manual mode
1 Auto Mode Start Encryption / Decryption in Auto mode

Bit 10 – CIPHER Encryption/ Decryption

ValueDescription
0 Decryption
1 Encryption

Bits 9:8 – KEYSIZE[1:0] Encryption Key Size

ValueNameDescription
0 128-bit Key 128-bit Key for Encryption / Decryption
1 192-bit Key 192-bit Key for Encryption / Decryption
2 256-bit Key 256-bit Key for Encryption / Decryption
3 Reserved Reserved

Bits 7:5 – CFBS[2:0] Cipher Feedback Block Size

ValueNameDescription
0 128-bit data block 128-bit Input data block for Encryption/Decryption in Cipher Feedback mode
1 64-bit data block 64-bit Input data block for Encryption/Decryption in Cipher Feedback mode
2 32-bit data block 32-bit Input data block for Encryption/Decryption in Cipher Feedback mode
3 16-bit data block 16-bit Input data block for Encryption/Decryption in Cipher Feedback mode
4 8-bit data block 8-bit Input data block for Encryption/Decryption in Cipher Feedback mode
5-7 Reserved Reserved

Bits 4:2 – AESMODE[2:0] AES Modes of Operation

ValueNameDescription
0 ECB Electronic code book mode
1 CBC Cipher block chaining mode
2 OFB Output feedback mode
3 CFB Cipher feedback mode
4 Counter Counter mode
5 CCM CCM mode
6 GCM Galois counter mode
7 Reserved Reserved

Bit 1 – ENABLE Enable

ValueDescription
0 The peripheral is disabled
1 The peripheral is enabled

Bit 0 – SWRST Software Reset

Writing a '0' to this bit has no effect.

Writing a '1' to this bit resets all registers in the AES module to their initial state, and the module will be disabled.

Writing a '1' to SWRST will always take precedence, meaning that all other writes in the same write operation will be discarded.

ValueDescription
0 There is no reset operation ongoing
1 The reset operation is ongoing