is processed after message data, so it is not possible to pre-calculate state for static associated data. Patents The catalyst for the development of CCM mode was the submission of offset codebook (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, before eventually being removed altogether. Use CCM mode is used in IEEE 802.11i (as CCMP, the CCM encryption protocol for WPA2), IPsec, and TLS 1.2, as well as Bluetooth Low Energy (as of Bluetooth 4.0). It is available for TLS 1.3, but not enabled by default in OpenSSL. See also Authenticated encryption EAX mode Galois/Counter Mode Stream cipher Stream cipher attacks CCMP References External links : Counter with CBC-MAC (CCM) : Using Advanced Encryption Standard (AES) CCM Mode with IPsec Encapsulating Security Payload (ESP) : AES-CCM Cipher Suites for Transport Layer Security (TLS) A Critique of CCM (by the designer of OCB) Block cipher modes of operation Authenticated-encryption schemes