I am using the python hmac module to generate an authentication code. Given a key, message, and hash function (I am using md5), the library returns an authentication code as a python bytes object. I am using the first
N bytes of the code, i.e.
digest is the variable storing the code.
How do I unambiguously (i.e. in a library-independent fashion) describe the truncation I am using? Would it be the N most-signficant bytes? Least-significant? If I declare that I am using the HMAC algorithm (RFC 2104) with md5 hash, is it sufficient to say that I take the "first N bytes" of the MAC?