Signature verification

 package main
 import (
         "crypto/hmac"
         "crypto/sha256"
         "encoding/hex"
         "fmt"
 )

 func main() {
         signatureKey := "your_secret_key" // Replace with your actual signature key
         payload := map[string]interface{}{
                 "event_type": "some_event",
                 "requestId": "12345",
                 // ... other payload fields
         }
         timestamp := "1690646400" // Replace with actual timestamp

         hashingPayload := fmt.Sprintf("%s:%s:%s:%s:%s:%s:%s:%s",
                 payload["event_type"],
                 payload["requestId"],
                 payload["data"]["merchant"]["userId"],
                 payload["data"]["merchant"]["walletId"],
                 payload["data"]["transaction"]["transactionId"],
                 payload["data"]["transaction"]["type"],
                 payload["data"]["transaction"]["time"],
                 payload["data"]["transaction"]["responseCode"])

         message := fmt.Sprintf("%s:%s", hashingPayload, timestamp)

         mac := hmac.New(sha256.New, []byte(signatureKey))
         mac.Write([]byte(message))
         hashed := mac.Sum(nil)
         digest = base64.StdEncoding.EncodeToString(hashed)
}

 import hmac
 import hashlib

 headers = request.headers
 signature = headers.get("nomba-sig-value") # extract signature value from nomba
 timestamp = headers.get("nomba-timestamp") # extract timestamp
 your_secret = "000000" # Replace with your actual secret if you have or use default secret "000000"

 data = request.get_json()

 # Construct the new payload string
 event_type = data["event_type"]
 request_id = data["requestId"]
 user_id = data["data"]["merchant"]["userId"]
 wallet_id = data["data"]["merchant"]["walletId"]
 transaction_id = data["data"]["transaction"]["transactionId"]
 transaction_type = data["data"]["transaction"]["type"]
 transaction_time = data["data"]["transaction"]["time"]
 transaction_response_code = data["data"]["transaction"]["responseCode"]

 concatenated_hashable_fields = ":".join(str(element) for element in [
     event_type,
     request_id,
     user_id,
     wallet_id,
     transaction_id,
     transaction_type,
     transaction_time,
     transaction_response_code,
     timestamp
 ] if element is not None)

 # Generate HMAC signature
 hmac_generated = generate_hmac(concatenated_hashable_fields, your_secret)

    const { createHmac } = await import("node:crypto");

    const signatureKey = "..."; // Replace with your actual signature key
    const payload = req.body; // Extract the request body

    // Extract timestamp from the header
    const timestamp = req.get("nomba-timestamp");

    // Construct the new payload string
    const hashingPayload = `${payload.event_type}:${payload.requestId}:${payload.data.merchant.userId}:${payload.data.merchant.walletId}:${payload.data.transaction.transactionId}:${payload.data.transaction.type}:${payload.data.transaction.time}:${payload.data.transaction.responseCode}`;

    // Combine the new payload with the timestamp
    const message = `${hashingPayload}:${timestamp}`;

    var hmacVal = createHmac("sha256", signatureKey);

    var signature = req.get("nomba-sig-value");
    hmacVal.update(message);

 import java.nio.charset.StandardCharsets;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
 import java.util.Objects;   

 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;

 public class SignatureGenerator {

     private static final String SIGNATURE_KEY = "..."; // Replace with your actual signature key
     private static final String ALGORITHM = "HmacSHA256";

     public static String generateSignature(String payload, String timestamp) throws NoSuchAlgorithmException, InvalidKeyException {
         final var eventType =  String.valueOf(requestPayload.getOrDefault("event_type",""));
         final var requestId = String.valueOf(requestPayload.getOrDefault("requestId", ""));
         final var userId =  String.valueOf(merchantHashMap.getOrDefault("userId", ""));
         final var walletId = String.valueOf(merchantHashMap.getOrDefault("walletId", ""));
         final var transactionId = String.valueOf(transactionHashMap.getOrDefault("transactionId", ""));
         final var transactionType = String.valueOf(transactionHashMap.getOrDefault("type", ""));
         final var transactionTime =   String.valueOf(transactionHashMap.getOrDefault("time", ""));
         final var transactionResponseCode = String.valueOf(transactionHashMap.getOrDefault("responseCode", ""));
         final var hashingPayload = String.format("%s:%s:%s:%s:%s:%s:%s:%s", eventType, requestId, userId, walletId, transactionId, transactionType, transactionTime, transactionResponseCode);

         String message = String.format("%s:%s", hashingPayload, timestamp);

         Mac sha256HMAC = Mac.getInstance(ALGORITHM);
         SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(), ALGORITHM);
         sha256HMAC.init(secretKey);
         byte[] hash = sha256HMAC.doFinal(hashingPayload.getBytes());
         return Base64.getEncoder().encodeToString(hash);
     }
 }

     using System;
     using System.Security.Cryptography;

     public class SignatureGenerator
     {
         private const string SignatureKey = "..."; // Replace with your actual signature key
         private const string Algorithm = "HmacSHA256";

         public static string GenerateSignature(string payload, string timestamp)
         {
             string hashingPayload = $"{payload["event_type"]}" +
                                 $":{payload["requestId"]}" +
                                 $":{payload["data"]["merchant"]["userId"]}" +
                                 $":{payload["data"]["merchant"]["walletId"]}" +
                                 $":{payload["data"]["transaction"]["transactionId"]}" +
                                 $":{payload["data"]["transaction"]["type"]}" +
                                 $":{payload["data"]["transaction"]["time"]}" +
                                 $":{payload["data"]["transaction"]["responseCode"]}";

             string message = $"{hashingPayload}:{timestamp}";

             byte[] keyBytes = Encoding.UTF8.GetBytes(SignatureKey);
             byte[] messageBytes = Encoding.UTF8.GetBytes(message);
             using (var hmac = new HMACSHA256(keyBytes))
             {
                 hmac.ComputeHash(messageBytes);
                 return Convert.ToHexString(hmac.Hash).ToUpper();
             }
         }
     }

    $input = file_get_contents("php://input"); //raw input
    $payload = json_decode($input, true); //decoded payload

    $signatureKey = ""; //your signature key

    $timestamp = $_SERVER['HTTP_NOMBA_TIMESTAMP']; //timestamp
    $signature = $_SERVER['HTTP_NOMBA_SIG_VALUE']; //signature

    // The payload
    $hashingPayload = $payload['event_type'] . ':' .
                $payload['requestId'] . ':' .
                $payload['data']['merchant']['userId'] . ':' .
                $payload['data']['merchant']['walletId'] . ':' .
                $payload['data']['transaction']['transactionId'] . ':' .
                $payload['data']['transaction']['type'] . ':' .
                $payload['data']['transaction']['time'] . ':' .
                $payload['data']['transaction']['responseCode'];

    // Combine d payload with d timestamp
    $message = $hashingPayload . ':' . $timestamp;


    // Generate HMAC hash using SHA256
    $calculatedSignature = hash_hmac('sha256', $message, $signatureKey,true);

    $encoded_data = base64_encode($calculatedSignature);