SPRUJB6B November 2024 – May 2025 AM2612
Figure 7-109 CCM OperationFigure 7-109 shows one round of a CCM (Counter with CBC-MAC) operation for both encryption and decryption. A 32-bit counter is used as IV (as it is for CTR mode). The data is encrypted in the same way as CTR mode, by XOR-ing the crypto core output with the input. Directly after the encrypt-operation, the plaintext is XOR-ed with the intermediate authentication result. The XOR result is used as input for a second encrypt-operation to calculate the next (intermediate) authentication result.
Refer to Section 7.4.4.3.7.3 for details about the CCM protocol.