Overview

using System;
using System.Security.Cryptography;
using System.Text;

class SignatureSampleCode
{
    public static string Sign(string merchantId, string xtimestamp, string merchantPrivateKey)
    {
        string content = $"{merchantId}|{xtimestamp}";

        using RSA rsa = RSA.Create();
        rsa.ImportFromPem(merchantPrivateKey);

        byte[] dataBytes = Encoding.UTF8.GetBytes(data);
        byte[] signedBytes = rsa.SignData(dataBytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);

        return Convert.ToBase64String(signedBytes);
    }

    static void Main()
    {
        string MERCHANT_ID = "";
        string MERCHANT_PRIVATE_KEY = ""; 

        Console.WriteLine(Sign(MERCHANT_ID, "2025-08-16T00:00:46+08:00", MERCHANT_PRIVATE_KEY));
    }
}

const crypto = require("crypto");

/**
 * Signs merchantId|timestamp using SHA256withRSA
 * @param {string} merchantId
 * @param {string} xtimestamp
 * @param {string} merchantPrivateKey your private key
 * @returns {string} Base64 signature
 */
function sign(merchantId, xtimestamp, merchantPrivateKey) {
    const content = `${merchantId}|${xtimestamp}`;

    // Sign data
    const signature = crypto.sign("sha256", Buffer.from(data, "utf8"), {
        key: privateKeyPem,
        padding: crypto.constants.RSA_PKCS1_PADDING
    });

    // Return Base64 signature
    return signature.toString("base64");
}

// Example usage
const MERCHANT_ID = "";
const MERCHANT_PRIVATE_KEY = "";

console.log(sign(MERCHANT_ID, "2025-08-16T00:00:46+08:00", MERCHANT_PRIVATE_KEY));

import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Base64;

public class SignatureSampleCode {

    /**
     * your private key, used to sign
     */
    private static final String MERCHANT_PRIVATE_KEY = "";

    /**
     * you merchantId
     */
    private static final String MERCHANT_ID = "";

    /**
     * @param merchantId    your merchantId
     * @param xtimestamp timestamp value, sample: 2025-08-16T00:00:46+08:00
     * @param merchant_private_key  your private key
     * @return
     */
    public static String sign(String merchantId, String xtimestamp, String merchant_private_key) {
        
        // content_to_be_signed
        String content = merchantId + "|" + xtimestamp;

        try {
            // sha256withRSA
            java.security.Signature signature = java.security.Signature.getInstance("SHA256withRSA");

            // privateKey
            PrivateKey priKey = KeyFactory.getInstance("RSA").generatePrivate(
                    new PKCS8EncodedKeySpec(Base64.getDecoder().decode(merchant_private_key.getBytes(StandardCharsets.UTF_8))));

            signature.initSign(priKey);
            signature.update(contentToBeSigned.getBytes(StandardCharsets.UTF_8));

            // sign
            byte[] signed = signature.sign();

            // base64Encode
            String base64EncodedSignature = new String(Base64.getEncoder().encode(signed), StandardCharsets.UTF_8);

            // urlEncode
            return base64EncodedSignature;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {
        System.out.println(sign( MERCHANT_ID, "2025-08-16T00:00:46+08:00", MERCHANT_PRIVATE_KEY));
    }

}