def open_tag

bend-collections@1.0.0.0 · spec/crypto/chacha20poly1305.bend:44

import Base
import bend-collections@1.0.0.0/spec/crypto/chacha.bend as CH

44# Decryption: the tag is recomputed over the received ciphertext and the
45# plaintext released only when it matches.
46def open_tag(ok: Bool, +key: List<&2, U32>, +nonce: List<&2, U32>, +ct: List<&2, U32>) -> Maybe<&2, List<&2, U32>>:
47  match ok:
48    case True{}: Some{CH.encrypt(key, 1, nonce, ct)}
49    case False{}: None{}