namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            string methodHash = "1a9d3de2408d240e3157fff159184d9e";
            string publicKey =
                "<RSAKeyValue><Modulus>pxDTxv/WaZCn9b/BaPjnTD83M/Y7nvswBS4Jm/7Ml6n8/KTkNPl5M1NGpQKtPBAN6qLR+BWPJQupQ3sWit1uwpIvXk6felC/Ee9Rsm66nFFqb2+pTrMc4uqSRKuUPq39iVJqwrtVCaIrDmtI+eEBsNVi9uVYnH6IcUp6d9yfPOM=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
            Encryptor encryptor = new Encryptor();
            string token = encryptor.EncryptRSA(methodHash, publicKey);
            Console.WriteLine(token);
        }
    }

    class Encryptor
    {
        private static UnicodeEncoding _encoder = new UnicodeEncoding();

        public string EncryptRSA(string data, string publicKey)
        {
            try
            {
                var rsa = new RSACryptoServiceProvider();
                rsa.FromXmlString(publicKey);
                
                Console.WriteLine(rsa.KeyExchangeAlgorithm);
                var dataToEncrypt = _encoder.GetBytes(data);
                var encryptedByteArray = rsa.Encrypt(dataToEncrypt, false).ToArray();
                var length = encryptedByteArray.Count();
                var item = 0;
                var sb = new StringBuilder();
                Console.WriteLine(length);
                foreach (var x in encryptedByteArray)
                {
                    item++;
                    sb.Append(x);
                    if (item < length)
                        sb.Append(",");
                }

                return sb.ToString();
            }
            catch (Exception ex)
            {
                throw new RSAException();
            }
        }

        class RSAException : Exception
        {
            public RSAException() : base("RSA Encryption Error")
            {
            }
        }
    }
}

String text = "1a9d3de2408d240e3157fff159184d9e";

        String _modulus = "pxDTxv/WaZCn9b/BaPjnTD83M/Y7nvswBS4Jm/7Ml6n8/KTkNPl5M1NGpQKtPBAN6qLR+BWPJQupQ3sWit1uwpIvXk6felC/Ee9Rsm66nFFqb2+pTrMc4uqSRKuUPq39iVJqwrtVCaIrDmtI+eEBsNVi9uVYnH6IcUp6d9yfPOM=";
        String _exponent = "AQAB";

        BigInteger modulus = new BigInteger(1, Base64Utils.decodeFromString(_modulus));
        BigInteger exponent = new BigInteger(1, Base64Utils.decodeFromString(_exponent));

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        RSAPublicKeySpec rsaPublicKeySpec = new RSAPublicKeySpec(modulus, exponent);
        PublicKey publicKey = keyFactory.generatePublic(rsaPublicKeySpec);
        
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] bytes = cipher.doFinal(text.getBytes(StandardCharsets.UTF_16LE));
   
        System.out.println(Arrays.toString(Base64Utils.encode(bytes)));