Package cmac implements the fast CMAC MAC based on
a block cipher. This mode of operation fixes security
deficiencies of CBC-MAC (CBC-MAC is secure only for
fixed-length messages). CMAC is equal to OMAC1.
This implementations supports block ciphers with a
block size of:
64 bit
128 bit
256 bit
512 bit
1024 bit
Common ciphers like AES, Serpent etc. operate on 128 bit
blocks. 256, 512 and 1024 are supported for the Threefish
tweakable block cipher. Ciphers with 64 bit blocks are
supported, but not recommened.
CMAC (with AES) is specified in RFC 4493 and RFC 4494.
Verify computes the CMAC checksum with the given tagsize of msg and compares
it with the given mac. This functions returns true if and only if the given mac
is equal to the computed one.