# What is CCM — Counter Mode Cipher Block Chaining Message Authentication Code Protocol

CCM puts together two different modes of operation (at least in the name). Does it mean data is encrypted using counter mode and then encrypted using CBC; kind of a double encryption?

• This is not an implementation of double-encryption. This is not $E(k_1, E(k_2, m))$. It is $E(k_1, m) || f(E(k_2, m))$ (where $f$ is just taking the last block). There is no "middle" to meet in here. – Stephen Touset Oct 10 '16 at 22:49