using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace Test
{
    public class HmacSha256
    {
        public string hash(string data, string secretKey)
        {
            var byteKey = Encoding.UTF8.GetBytes(secretKey);
            var byteData = Encoding.UTF8.GetBytes(data);
            HMACSHA256 hmacSHA256 = new HMACSHA256(byteKey);
            var hashDataByte = hmacSHA256.ComputeHash(byteData);
            var encrypted = this.ByteToString(hashDataByte);
            return encrypted.ToLower();
        }

        private string ByteToString(byte[] buff)
        {
            string sbinary = "";

            for (int i = 0; i < buff.Length; i++)
            {
                sbinary += buff[i].ToString("X2"); // hex format
            }
            return (sbinary);
        }
    }
}

    private function getData()
    {
        $plainText = $this->cpCode . "|" . $this->requestId . "|" . $this->gameCode . "|" . $this->returnUrl . "|" . $this->account . "|" . $this->accessKey;
        $signature = hash_hmac("sha256", $plainText, $this->secretKey);
        $plainText = $plainText . "|" . $signature;

        $strBase64Encode = base64_encode($plainText);
        return $strBase64Encode;
    }