stringToSign := getStringToSignV2(method, encodedResource, encodedQuery, headers, expires)
	return calculateSignatureV2(stringToSign, cred.SecretKey)
}

// Return the signature v2 of a given request.
func signatureV2(cred auth.Credentials, method string, encodedResource string, encodedQuery string, headers http.Header) string {
	stringToSign := getStringToSignV2(method, encodedResource, encodedQuery, headers, "")