Constant MAC_CMAC 

pub const MAC_CMAC: u8 = b'c';

CMAC (AES-based)

Algorithm: Cipher-based Message Authentication Code using AES Fixed output: 16 bytes (128 bits) Security: 128-bit security level Use case: AES-based systems, hardware acceleration available Note: Slower than HMAC/Poly1305 but useful when AES is already in use