func NewChecksumWithType(alg ChecksumType, value string) *Checksum {
	if !alg.IsSet() {
		return nil
	}
	wantParts := 0
	if strings.ContainsRune(value, '-') {
		valSplit := strings.Split(value, "-")
		if len(valSplit) != 2 {
			return nil
		}
		value = valSplit[0]
		nParts, err := strconv.Atoi(valSplit[1])
		if err != nil {
			return nil
		}
		alg |= ChecksumMultipart
		wantParts = nParts

	if err != nil {
		return nil, &jwtgo.ValidationError{Inner: err, Errors: jwtgo.ValidationErrorMalformed}
	}
	headerDec := buf[:n]
	buf = buf[n:]

	alg, _, _, err := jsonparser.Get(headerDec, "alg")
	if err != nil {
		return nil, &jwtgo.ValidationError{Inner: err, Errors: jwtgo.ValidationErrorMalformed}
	}

	n, err = base64DecodeBytes(token[i+1:j], buf)
	if err != nil {

// Does not update anything in cr.
func (cr *s3ChunkedReader) getChunkSignature() string {
	hashedChunk := hex.EncodeToString(cr.chunkSHA256Writer.Sum(nil))

	// Calculate string to sign.
	alg := signV4ChunkedAlgorithm + "\n"
	stringToSign := alg +
		cr.seedDate.Format(iso8601Format) + "\n" +
		getScope(cr.seedDate, cr.region) + "\n" +
		cr.seedSignature + "\n" +
		emptySHA256 + "\n" +
		hashedChunk

	// Get hmac signing key.

          "e":"AQAB",
          "alg":"RS256",
          "kid":"2011-04-29"}
       ]
     }`

	var jk JWKS
	if err := json.Unmarshal([]byte(jsonkey), &jk); err != nil {
		t.Fatal("Unmarshal: ", err)
	} else if len(jk.Keys) != 2 {