ECB解密问题中的c#三重DES

我有这个PHP脚本，我们需要转换为c#来解码来自API post请求的结果，但我遇到了c#实现的问题。

我们在运行PHP脚本XXXX-XXXX-XXXX时得到了很好的结果，但是得到了不同的错误。

的值是:

encodedText = "U8Q+m2zpFMLa/3gYILHx5w=="
key = "examplesecret"
keyHash = "6315046b2c085bbeeab87c65"

<?php
$secret = 'examplesecret';
$encrypted_code = 'U8Q+m2zpFMLa/3gYILHx5w==';
// Base64
// Decode
$encrypted_code = base64_decode( $encrypted_code );
// Create decryption module
$cipher = mcrypt_module_open( 'tripledes', '', 'ecb', '' );
$keysize = mcrypt_enc_get_key_size( $cipher ); // = 24
// Generate key
$hash = md5( $secret );
$key = substr( $hash, 0, $keysize );
// Initialise decrypter
$iv = mcrypt_create_iv( mcrypt_enc_get_iv_size( $cipher ),
MCRYPT_DEV_RANDOM );
mcrypt_generic_init( $cipher, $key, $iv );
// Decrypt code
$decrypted = mdecrypt_generic( $cipher, $encrypted_code );
// Output decrypted code
echo $decrypted;
?>

public static string Decrypt(string encodedText, string key)
{
    TripleDESCryptoServiceProvider desCryptoProvider = new TripleDESCryptoServiceProvider();
    MD5CryptoServiceProvider hashMD5Provider = new MD5CryptoServiceProvider();
    byte[] byteHash;
    byte[] byteBuff;
    byteHash = hashMD5Provider.ComputeHash(Encoding.UTF8.GetBytes(key));
    desCryptoProvider.Key = byteHash;
    desCryptoProvider.Padding = PaddingMode.None;
    desCryptoProvider.Mode = CipherMode.ECB; //CBC, CFB
    byteBuff = Convert.FromBase64String(encodedText);
    var byteHex = BitConverter.ToString(byteBuff).Replace("-", " ");
    string plaintext = Encoding.UTF8.GetString(desCryptoProvider.CreateDecryptor().TransformFinalBlock(byteHex, 0, byteHex.Length));
    return plaintext;
}