PHP and C# common encryption and decryption function class, Use of 3DES encryption and decryption

function encrypt($string) {
        //Key
        $key = "xxxxxxxx";

        //Encryption
        $cipher_alg = MCRYPT_TRIPLEDES;

        $iv = mcrypt_create_iv(mcrypt_get_iv_size($cipher_alg,MCRYPT_MODE_ECB), MCRYPT_RAND); 

        $encrypted_string = mcrypt_encrypt($cipher_alg, $key, $string, MCRYPT_MODE_ECB, $iv);
        return base64_encode($encrypted_string);
        return $encrypted_string;
    }

    function decrypt($string) {
            $string = base64_decode($string);

            //key
            $key = "xxxxxxxx";

            $cipher_alg = MCRYPT_TRIPLEDES;

            $iv = mcrypt_create_iv(mcrypt_get_iv_size($cipher_alg,MCRYPT_MODE_ECB), MCRYPT_RAND); 

            $decrypted_string = mcrypt_decrypt($cipher_alg, $key, $string, MCRYPT_MODE_ECB, $iv);
            return trim($decrypted_string);
    }

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

public class Crypto3DES
{
    public Crypto3DES()
    {

    }

    private System.Text.Encoding encoding;

    public string Key
    {
        get
        {
            return "xxxxxxxx";
        }
    }

    public System.Text.Encoding Encoding
    {
        get
        {
            if( encoding == null )
            {
                encoding = System.Text.Encoding.UTF8;
            }
            return encoding;
        }

        set
        {
            encoding = value;
        }
    }

    public string Encrypt3DES( string strString )
    {
        DESCryptoServiceProvider DES = new DESCryptoServiceProvider();

        DES.Key = Encoding.GetBytes( this.Key );
        DES.Mode = CipherMode.ECB;
        DES.Padding = PaddingMode.Zeros;

        ICryptoTransform DESEncrypt = DES.CreateEncryptor();

        byte[] Buffer = encoding.GetBytes(strString);

        return Convert.ToBase64String(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length));
    }

    public string Decrypt3DES( string strString )
    {
        DESCryptoServiceProvider  DES = new DESCryptoServiceProvider ();

        DES.Key = Encoding.UTF8.GetBytes( this.Key );
        DES.Mode = CipherMode.ECB;
        DES.Padding = PaddingMode.Zeros;
        ICryptoTransform DESDecrypt = DES.CreateDecryptor();

        byte[] Buffer = Convert.FromBase64String(strString);
        return UTF8Encoding.UTF8.GetString( DESDecrypt.TransformFinalBlock(Buffer, 0, Buffer.Length) );
    }
}