Counter Mode Cipher Block Chaining Message Authentication Code Protocol (Counter Mode CBC-MAC Protocol) or CCM mode Protocol (CCMP) is an

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can dec ...

protocol designed for

Wireless LAN A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building ...

products that implements the standards of the

IEEE 802.11i IEEE 802.11i-2004, or 802.11i for short, is an amendment to the original IEEE 802.11, implemented as Wi-Fi Protected Access II (WPA2). The draft standard was ratified on 24 June 2004. This standard specifies security mechanisms for wireless networ ...

amendment to the original IEEE 802.11 standard. CCMP is an enhanced data cryptographic encapsulation mechanism designed for data confidentiality and based upon the Counter Mode with CBC-MAC ( CCM mode) of the

Advanced Encryption Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a variant ...

(AES) standard. It was created to address the vulnerabilities presented by

Wired Equivalent Privacy Wired Equivalent Privacy (WEP) was a security algorithm for 802.11 wireless networks. Introduced as part of the original IEEE 802.11 standard ratified in 1997, its intention was to provide data confidentiality comparable to that of a traditional ...

(WEP), a dated, insecure protocol.

Technical details

CCMP uses

CCM CCM may refer to: * Cubic centimetre (''ccm''), metric unit of volume * Climate change mitigation (''CCM''), climate change topic Biology and medicine * Calcium concentration microdomains, part of a cell's cytoplasm * Photosynthesis#Carbon ...

that combines CTR mode for data confidentiality and cipher block chaining message authentication code (CBC-MAC) for authentication and integrity. CCM protects the integrity of both the MPDU data field and selected portions of the IEEE 802.11 MPDU header. CCMP is based on AES processing and uses a 128-bit key and a 128-bit block size. CCMP uses CCM with the following two parameters: * M = 8; indicating that the MIC is 8 octets (eight bytes). * L = 2; indicating that the Length field is 2 octets. A CCMP Medium Access Control Protocol Data Unit (MPDU) comprises five sections. The first is the MAC header which contains the destination and source address of the data packet. The second is the CCMP header which is composed of 8 octets and consists of the packet number (PN), the Ext IV, and the key ID. The packet number is a 48-bit number stored across 6 octets. The PN codes are the first two and last four octets of the CCMP header and are incremented for each subsequent packet. Between the PN codes are a reserved octet and a Key ID octet. The Key ID octet contains the Ext IV (bit 5), Key ID (bits 6–7), and a reserved subfield (bits 0–4). CCMP uses these values to encrypt the data unit and the MIC. The third section is the data unit which is the data being sent in the packet. The fourth is the message integrity code (MIC) which protects the integrity and authenticity of the packet. Finally, the fifth is the frame check sequence (FCS) which is used for error detection and correction. Of these sections only the data unit and MIC are encrypted.

Security

CCMP is the standard encryption protocol for use with the Wi-Fi Protected Access II (WPA2) standard and is much more secure than the

(WEP) protocol and Temporal Key Integrity Protocol (TKIP) of

Wi-Fi Protected Access Wi-Fi Protected Access (WPA), Wi-Fi Protected Access II (WPA2), and Wi-Fi Protected Access 3 (WPA3) are the three security and security certification programs developed after 2000 by the Wi-Fi Alliance to secure wireless computer networks. The Al ...

(WPA). CCMP provides the following security services: * Data confidentiality; ensures only authorized parties can access the information * Authentication; provides proof of genuineness of the user * Access control in conjunction with layer management Because CCMP is a block cipher mode using a 128-bit key, it is secure against attacks to the 2⁶⁴ steps of operation. Generic meet-in-the-middle attacks do exist and can be used to limit the theoretical strength of the key to 2^''n''/2 (where ''n'' is the number of bits in the key) operations needed.

Known attacks

References

{{DEFAULTSORT:Ccmp Cryptographic protocols Wireless networking IEEE 802.11 Secure communication Key management