HmacUtil - Sha512 - For Bpay Only

Sample codes for reference - To generate HMAC for the header

JAVA - Implementation

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.GeneralSecurityException;
import java.util.Base64;

public class HMACUtil {

    private HMACUtil() {}

    public static String calculateHMAC(String signatureKey, String textToHash) {
        try {
            byte[] signatureKeyInByteArray = hexStringToByteArray(signatureKey);

            SecretKeySpec secretKeySpec = new SecretKeySpec(signatureKeyInByteArray, "HmacSHA512");
            Mac mac = Mac.getInstance("HmacSHA512");
            mac.init(secretKeySpec);

            return Base64.getEncoder().encodeToString(mac.doFinal(textToHash.getBytes()));
        } catch(GeneralSecurityException ignored) {
           
        }

        return "";
    }

    private static byte[] hexStringToByteArray(String str) {
        int len = str.length();
        byte[] data = new byte[len / 2];

        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(str.charAt(i), 16) << 4) + Character.digit(str.charAt(i + 1), 16));
        }

        return data;
    }
}

Hmac Util on NodeJS with crypto lib.

export const computeHMAC = (clientId, dateTime, requestPayload, secretKey) => {
    const message = `${clientId}${dateTime}${JSON.stringify(requestPayload).replaceAll(":", ": ").replaceAll(",", ", ")}`;
    const keyBuffer = Buffer.from(secretKey, 'hex');
    const hmac = crypto.createHmac('sha512', keyBuffer);
    return hmac.update(message, 'utf8').digest('base64');
};