using System;

using System.Security.Cryptography;

using System.Text;

public class Program

{

    public static void Main()

    {

         const string sentPayload = @"{""attempt"":5,""eventLogId"":""bec12db7-a2a7-4a47-a349-64108c0c979a"",""event"":""acceptance-check-created"",""acceptanceCheckId"":""ZZJE""}";

            const string signatureSecretSetInWebhookEditPage = "403f4169f406423297454a028accb81d";

            const string signatureSentInHeader = "o7GTfXOGUcpCLszmq4Mu4o7YMkhzL7mPTiEI9koisvg=";

​

            var calculatedSignatureByWebhookCallReceiver = CreateSignatureToken(sentPayload, signatureSecretSetInWebhookEditPage);

​

            var isValidSignature = signatureSentInHeader.Equals(calculatedSignatureByWebhookCallReceiver);

​

            Console.WriteLine("Signature Is valid: {0}", isValidSignature);

​

    }

     private static string CreateSignatureToken(string payload, string verificationSignature)

        {

            var secretBytes = Encoding.UTF8.GetBytes(verificationSignature);

​

            using (var hasher = new HMACSHA256(secretBytes))

            {

                var data = Encoding.UTF8.GetBytes(payload);

                var signatureBytes = hasher.ComputeHash(data);

​

                var token = Convert.ToBase64String(signatureBytes);

​

                return token;

            }

        }

}