61.5.2 TDES Mode Register
| Name: | TDES_MR |
| Offset: | 0x04 |
| Reset: | 0x00000002 |
| Property: | Read/Write |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| Access | |||||||||
| Reset |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| CFBS[1:0] | |||||||||
| Access | R/W | R/W | |||||||
| Reset | 0 | 0 | |||||||
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| LOD | OPMOD[1:0] | SMOD[1:0] | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 0 | 0 | 0 | 0 | ||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| KEYMOD | TDESMOD[1:0] | CIPHER | |||||||
| Access | R/W | R/W | R/W | R/W | |||||
| Reset | 0 | 0 | 1 | 0 | |||||
Bits 17:16 – CFBS[1:0] Cipher Feedback Data Size
| Value | Name | Description |
|---|---|---|
| 0 | SIZE_64BIT | 64 bits |
| 1 | SIZE_32BIT | 32 bits |
| 2 | SIZE_16BIT | 16 bits |
| 3 | SIZE_8BIT | 8 bits |
Bit 15 – LOD Last Output Data Mode
| Value | Description |
|---|---|
| 0 | No effect. After each end of encryption/decryption, the output data is available either on TDES_ODATARx (Manual and Auto modes) . In Manual and Auto modes, the DATRDY flag is cleared when at least one of the TDES_ODATARx is read. |
| 1 | The DATRDY flag is cleared when at least one of the Input Data Registers is written. No further TDES_ODATARx reads are necessary between consecutive encryptions/decryptions (see Last Output Data Mode). |
Bits 13:12 – OPMOD[1:0] Operating Mode
For CBC-MAC operating mode, set OPMOD to CBC and LOD to 1.
| Value | Name | Description |
|---|---|---|
| 0 | ECB | Electronic Code Book mode |
| 1 | CBC | Cipher Block Chaining mode |
| 2 | OFB | Output Feedback mode |
| 3 | CFB | Cipher Feedback mode |
Bits 9:8 – SMOD[1:0] Start Mode
If a DMA transfer is used, 0x2 must be configured. See DMA Mode for more details.
| Value | Name | Description |
|---|---|---|
| 0 | MANUAL_START | Manual mode |
| 1 | AUTO_START | Auto mode |
| 2 | IDATAR0_START | TDES_IDATAR0 accesses only Auto mode |
Bit 4 – KEYMOD Key Mode
| Value | Description |
|---|---|
| 0 | Three-key algorithm is selected. |
| 1 | Two-key algorithm is selected. There is no need to write TDES_KEY3WRy. |
Bits 2:1 – TDESMOD[1:0] ALGORITHM Mode
Values which are not listed in the table must be considered as “reserved”.
| Value | Name | Description |
|---|---|---|
| 0 | SINGLE_DES | Single DES processing using TDES_KEY1WRy. |
| 1 | TRIPLE_DES | Triple DES processing using TDES_KEY1WRy, TDES_KEY2WRy and TDES_KEY3WRy . |
| 2 | XTEA | XTEA processing using TDES_KEY1WRy and TDES_KEY2WRy. |
Bit 0 – CIPHER Processing Mode
| Value | Name | Description |
|---|---|---|
| 0 | DECRYPT | Decrypts data. |
| 1 | ENCRYPT | Encrypts data. |