ECB — AES electronic codebook mode encryption

The AES electronic codebook mode encryption (ECB) can be used for a range of cryptographic functions like hash generation, digital signatures, and keystream generation for data encryption/decryption. The ECB encryption block supports 128 bit AES encryption (encryption only, not decryption).

The main features of ECB are:

• 128-bit AES encryption
• Supports standard AES ECB block encryption
• Memory-to-memory operations using Scatter/Gather DMA

The inputs and outputs of the ECB are illustrated below.

AES ECB uses EasyDMA with scatter-gather to access to memory for in-place operations on cleartext and ciphertext during encryption. ECB uses the same AES core as the CCM and AAR blocks and is an asynchronous operation which may not complete if the AES core is busy.

AES ECB performs a 128 bit AES block encrypt. At the START task, cleartext is loaded into the ECB from memory described by the scatter/gather job list pointed to by INPTR and the ciphertext is written into memory described by the job list pointed to by OUTPTR. When the last cleartext byte has been encrypted and written to OUTPTR, the END event is triggered.

The following figure illustrates how the input and output job lists can be configured. For more details of the joblists, see EasyDMA.

The AES key is set by writing the KEY.VALUE key registers. The same key can be used to encrypt multiple blocks by triggering the START task multiple times.

AES ECB can be stopped by triggering the STOP task.

          {0x02, 0x13, 0x24, 0x35, 0x46, 0x57, 0x68, 0x79, 0xAC, 0xBD, 0xCE, 0xDF, 0xE0, 0xF1, 0x02, 0x13}
      

          {0x99, 0xAD, 0x1B, 0x52, 0x26, 0xA3, 0x7E, 0x3E, 0x05, 0x8E, 0x3B, 0x8E, 0x27, 0xC2, 0xC6, 0x66}