h := hashPool.Get().(hash.Hash)

	h.Reset()

	// try to force stack allocation
	var a [4]byte
	b := a[:]

	writeLengthPrefixedString(h, b, token)
	// encode the length of audiences to avoid ambiguities
	writeLength(h, b, len(auds))
	for _, aud := range auds {
		writeLengthPrefixedString(h, b, aud)
	}

	key := toString(h.Sum(nil)) // skip base64 encoding to save an allocation

	hashPool.Put(h)