From Wikipedia, the free encyclopedia

CCM mode (Counter with CBC-MAC) is a mode of operation for cryptographic block ciphers. It is an authenticated encryption algorithm designed to provide both authentication and privacy. CCM mode is only defined for 128-bit block ciphers. In RFC 3610, it is defined for use with 128-bit AES.

Contents 1 Encryption and authentication 2 Performance 3 Patents 4 See also 5 External links 6 References

As the name suggests, CCM mode combines the well-known counter mode of encryption with the well-known CBC-MAC mode of authentication. The key insight is that the same encryption key can be used for both, provided that the counter values used in the encryption do not collide with the (pre-)initialization vector used in the authentication. A proof of security exists for this combination, based on the security of the underlying block cipher. In fact, the proof also applies to a generalization of CCM for any size block cipher, and in fact, for any size cryptographically strong pseudo-random function (since in both counter mode and CBC-MAC, the block cipher is only ever used in one direction).

CCM mode was designed by Russ Housley, Doug Whiting and Niels Ferguson. At the time CCM mode was developed, Russ Housley was employed by RSA Laboratories.

A minor variation of the CCM, so called CCM*, is used in ZigBee standard. CCM* includes all of the features of CCM and additionally offers encryption-only and integrity-only capabilities.

CCM requires two block cipher encryption operations per each block of encrypted and authenticated message and one encryption per each block of associated authenticated data.

The catalyst for the development of CCM mode was the submission of OCB mode for inclusion in the IEEE 802.11i standard. Opposition was voiced to the inclusion of OCB mode because of a pending patent application on the algorithm. Inclusion of a patented algorithm meant significant licensing complications for implementors of the standard.

While the inclusion of OCB mode was disputed based on these intellectual property issues, it was agreed that the simplification provided by an authenticated encryption system was desirable. Therefore Housley, et al. developed CCM mode as a potential alternative that was not encumbered by patents.

Even though CCM mode is less efficient than OCB mode, a patent free solution was preferable to one complicated by patent licensing issues. Therefore, CCM mode went on to become a mandatory component of the IEEE 802.11i standard, and OCB mode was relegated to optional component status.

• EAX mode

• A Critique of CCM
• RFC 3610: Counter with CBC-MAC (CCM)
• RFC 4309: Using Advanced Encryption Standard (AES) CCM Mode with IPsec Encapsulating Security Payload (ESP)

• NIST Special Publication 800-38C Recommendation for Block Cipher Modes of Operation: The CCM Mode for Authentication and Confidentiality

Cryptographic hash functions and Message authentication codes (MACs) v • d • e
Hash algorithms: Gost-Hash | HAS-160 | HAS-V | HAVAL | MDC-2 | MD2 | MD4 | MD5 | N-Hash | RadioGatún | RIPEMD | SHA family | Snefru | Tiger | VEST | WHIRLPOOL | crypt(3) DES
MAC algorithms: DAA | CBC-MAC | HMAC | OMAC/CMAC | PMAC | UMAC | Poly1305-AES | VEST
Authenticated encryption modes: CCM | EAX | GCM | OCB | VEST   Attacks: Birthday attack | Collision attack | Preimage attack | Rainbow table | Brute force attack
Standardization: CRYPTREC | NESSIE   Misc: Avalanche effect | Hash collision | Hash functions based on block ciphers
Block ciphers v • d • e
Algorithms: 3-Way | AES | Akelarre | Anubis | ARIA | BaseKing | Blowfish | C2 | Camellia | CAST-128 | CAST-256 | CIKS-1 | CIPHERUNICORN-A | CIPHERUNICORN-E | CMEA | Cobra | COCONUT98 | Crab | CRYPTON | CS-Cipher | DEAL | DES | DES-X | DFC | E2 | FEAL | FROG | G-DES | GOST | Grand Cru | Hasty Pudding Cipher | Hierocrypt | ICE | IDEA | IDEA NXT | Iraqi | Intel Cascade Cipher | KASUMI | KHAZAD | Khufu and Khafre | KN-Cipher | Libelle | LOKI89/91 | LOKI97 | Lucifer | M6 | MacGuffin | Madryga | MAGENTA | MARS | Mercy | MESH | MISTY1 | MMB | MULTI2 | NewDES | NOEKEON | NUSH | Q | RC2 | RC5 | RC6 | REDOC | Red Pike | S-1 | SAFER | SC2000 | SEED | Serpent | SHACAL | SHARK | Skipjack | SMS4 | Square | TEA | Triple DES | Twofish | UES | Xenon | xmx | XTEA | Zodiac
Design: Feistel network | Key schedule | Product cipher | S-box | SPN Attacks: Brute force | Linear / Differential / Integral cryptanalysis | Mod n | Related-key | Slide | XSL
Standardization: AES process | CRYPTREC | NESSIE Misc: Avalanche effect | Block size | IV | Key size | Modes of operation | Piling-up lemma | Weak key
Cryptography v • d • e
History of cryptography | Cryptanalysis | Cryptography portal | Topics in cryptography
Symmetric-key algorithm | Block cipher | Stream cipher | Public-key cryptography | Cryptographic hash function | Message authentication code | Random numbers