// Calculate signature.
	newSignature := getSignature(signingKey, stringToSign)

	// Verify if signature match.
	if !compareSignatureV4(newSignature, signV4Values.Signature) {
		return cred, "", "", time.Time{}, ErrSignatureDoesNotMatch
	}

	// Return calculated signature.
	return cred, newSignature, region, date, ErrNone
}