Crypto.hmac_sha256

Crypto.hmac_sha256(key, msg) -> string

Computes HMAC-SHA256 over msg under the secret key (RFC 2104) and returns the 64-character lowercase hex tag. Unlike a bare hash, a MAC cannot be recomputed without the key, so it authenticates the message: attach the tag to a save file or a network packet, and a receiver who shares the key can tell whether the payload was altered or forged. To check the tag on the other side, pass it to Crypto.verify_hmac rather than comparing hex with ==.

Parameters

keythe shared secret; keep it out of the shipped client where you can

msgthe payload being signed

Example

program SignSave {
  entry {
    let key = "s3cret"
    let payload = "score=9001;level=12"
    let mac = Crypto.hmac_sha256(key, payload)
    print(mac)
  }
}

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