d8f06b24bb
Add RC6 block cipher encrypt/decrypt operations. RC6 is a symmetric block cipher designed by Ron Rivest et al. It was an AES finalist and supports 128/192/256-bit keys. Features: - ECB, CBC, CFB, OFB, CTR modes - Multiple padding options (PKCS7, Zero, None) - 128-bit block size, 20 rounds Includes official test vectors from IETF draft.