HMAC

This module implements the HMAC algorithm, as described by RFC 2104 (https://tools.ietf.org/html/rfc2104.html). HMAC (which stands for hash-based message authentication code or keyed-hash message authentication code, depending on who you ask) is a widely used mechanism for authenticating messages and verifying that they have not been tampered with.

The algorithm combines a message with a secret key and generates a hash of the combination. This hash is referred to as a message authentication code (MAC) or signature. The signature is stored or transmitted along with the message. At a later time, you can verify that the message has not been tampered with by re-computing the signature using the same secret key and comparing it to the previously computed signature. The secret key must be carefully protected, otherwise an attacker with access to the key would be able to modify the message and replace the signature, thereby defeating the authentication mechanism.

Let's...