View Source Plug.Crypto.MessageVerifier (Plug.Crypto v2.0.0)
MessageVerifier makes it easy to generate and verify messages
which are signed to prevent tampering.
For example, the cookie store uses this verifier to send data to the client. The data can be read by the client, but cannot be tampered with.
The message and its verification are base64url encoded and returned to you.
The current algorithm used is HMAC-SHA, with SHA256, SHA384, and SHA512 as supported digest types.