Function `keyed_hash`

fn keyed_hash(key: &[u8; 32], input: &[u8]) -> Hash

The keyed hash function.

This is suitable for use as a message authentication code, for example to replace an HMAC instance. In that use case, the constant-time equality checking provided by Hash is almost always a security requirement, and callers need to be careful not to compare MACs as raw bytes.

For an incremental version that accepts multiple writes, see Hasher::new_keyed, Hasher::update, and Hasher::finalize. These two lines are equivalent:

# const KEY: &[u8; 32] = &[0; 32];
let mac = blake3::keyed_hash(KEY, b"foo");
# let mac1 = mac;

let mac = blake3::Hasher::new_keyed(KEY).update(b"foo").finalize();
# let mac2 = mac;
# assert_eq!(mac1, mac2);

For output sizes other than 32 bytes, see Hasher::finalize_xof, and OutputReader.

This function is always single-threaded. For multithreading support, see Hasher::update_rayon.