func getCredentialString(accessKeyID, location string, t time.Time) string {
	return accessKeyID + SlashSeparator + getScope(t, location)
}

// getMD5HashBase64 returns MD5 hash in base64 encoding of given data.
func getMD5HashBase64(data []byte) string {
	return base64.StdEncoding.EncodeToString(getMD5Sum(data))
}

// Returns new HTTP request object.