const crypto = require('crypto');

// 1. Create random string for value.
const signatureValue = crypto.randomBytes(64).toString('hex');

// 2. Get current timestamp in seconds.
const timestamp = Math.floor(Date.now() / 1000);

// 3. Assemble
const signatureString = `${signatureValue}.${signatureValue.length}.${timestamp}`;

// 4. Generate HMAC and output Base64
const signature = crypto.createHmac('SHA256','{your_shared_secret}').update(signatureString).digest('base64');

import base64
import hmac
import hashlib
import uuid
import time

# 1. Use GUID for our 'random' string value.
signature_value = str(uuid.uuid4())

# 2. Get current timestamp in seconds.
timestamp = int(time.time())

# 3. Assemble
signature_string = f"{signature_value}.{len(signature_value)}.{timestamp}"

# 4. Generate HMAC and output Base64
key = b"{your_shared_secret}"
message = signature_string.encode("utf-8")

digest = hmac.new(key, message, hashlib.sha256).digest()
signature = base64.b64encode(digest).decode("utf-8")

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

// 1. Use GUID for our 'random' string value.
var signatureValue = Guid.NewGuid().ToString();

// 2. Get current timestamp in seconds.
int secondsSinceEpoch = (int)DateTimeOffset.UtcNow.ToUnixTimeSeconds();

// 3. Assemble
var data = $"{signatureValue}.{signatureValue.Length}.{secondsSinceEpoch}";

// 4. Generate HMAC and output Base64
using var hashObject = new HMACSHA256(Encoding.UTF8.GetBytes("{your_shared_secret}"));
var signatureHmac = hashObject.ComputeHash(Encoding.UTF8.GetBytes(data));
var signature = Convert.ToBase64String(signatureHmac);

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;
import java.util.UUID;

public class SignatureExample {
    public static void main(String[] args) throws Exception {

        // 1. Use GUID for our 'random' string value.
        String signatureValue = UUID.randomUUID().toString();

        // 2. Get current timestamp in seconds.
        long timestamp = System.currentTimeMillis() / 1000;

        // 3. Assemble
        String signatureString = signatureValue + "." + signatureValue.length() + "." + timestamp;

        // 4. Generate HMAC and output Base64
        String secret = "{your_shared_secret}";
        Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
        SecretKeySpec secretKey = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
        sha256_HMAC.init(secretKey);

        byte[] hash = sha256_HMAC.doFinal(signatureString.getBytes(StandardCharsets.UTF_8));
        String signature = Base64.getEncoder().encodeToString(hash);

        System.out.println("Signature: " + signature);
    }
}

import crypto from "crypto";

// 1. Create random string for value.
const signatureValue = crypto.randomBytes(64).toString("hex");

// 2. Get current timestamp in seconds.
const timestamp = Math.floor(Date.now() / 1000);

// 3. Assemble
const signatureString = `${signatureValue}.${signatureValue.length}.${timestamp}`;

// 4. Generate HMAC and output Base64
const secret = "{your_shared_secret}";
const signature = crypto
  .createHmac("sha256", secret)
  .update(signatureString)
  .digest("base64");

console.log("signatureValue:", signatureValue);
console.log("timestamp:", timestamp);
console.log("signature:", signature);