I have messages with the following fixed lengths:
- 4 byte
- 8 byte
- 16 byte
I want to encrypted them and prevent modification by appending an authentication tag using a MAC algorithm of my choosing (e.g. using Encrypt-then-Mac schema). Additionally I want the cipher output message to be as short as possible.
Let's say the normal MAC output size would be 16 byte (e.g CMAC with AES). Can I truncate the MAC with a short message like 4 byte to get similar security assurances?
According to various NIST standards, minimum lengths of MAC from 64 bit (CMAC) to 96 bit (GMAC) are recommended.