A message authentication code (MAC), or tag, is a security code that is typed in by the user of a computer to access accounts or portals.

The HMAC is a specific, albeit special type of message authentication code that couples a cryptographic mathematical hashing function along with pre-shared secret cryptographic keys.

Cryptographic hash functions are mathematical functions that are often used with cryptocurrency. Find out in this guide how they work and what their role is.

Among other desirable properties of hash functions, an interesting one is that it should be collision-resistant, that is it should be difficult to find two messages with the same hash value.