go/src/crypto/hmac/hmac.go

// New returns a new HMAC hash using the given [hash.Hash] type and key.
// New functions like [crypto/sha256.New] can be used as h.
// h must return a new Hash every time it is called.
// Note that unlike other hash implementations in the standard library,
// the returned Hash does not implement [encoding.BinaryMarshaler]
// or [encoding.BinaryUnmarshaler].
func New(h func() hash.Hash, key []byte) hash.Hash { … }

// Equal compares two MACs for equality without leaking timing information.
func Equal(mac1, mac2 []byte) bool { … }