Sign and Verify a Message With an HMAC Digest using cryptokit

Task

Cryptography / Sign and Verify a Message With an HMAC Digest

Opam Packages Used

• cryptokit Tested with version: 1.18 — Used libraries: cryptokit

Code

(* We use `Cryptokit.MAC.hmac_sha256` to create a hash function using HMAC-SHA256 from the given key, and then apply the hash function to the message. *) let hmac ~key msg = let hash = Cryptokit.MAC.hmac_sha256 key in Cryptokit.hash_string hash msg (* Sign the given message. Return a pair of the message and its MAC. *) let sign ~key msg = (msg, hmac ~key msg) (* Verify the signature on a message. Return `true` if the signature is valid, `false` otherwise. *) let verify ~key (msg, mac) = hmac ~key msg = mac let _ = let key = "supercalifragilisticexpialidocious" and msg = "Mary Poppins" in assert (verify ~key (sign ~key msg))

let hmac ~key msg =
  let hash = Cryptokit.MAC.hmac_sha256 key in
  Cryptokit.hash_string hash msg

let sign ~key msg =
  (msg, hmac ~key msg)

let verify ~key (msg, mac) =
  hmac ~key msg = mac

let _ =
  let key = "supercalifragilisticexpialidocious"
  and msg = "Mary Poppins" in
  assert (verify ~key (sign ~key msg))

Recipe not working? Comments not clear or out of date?