Unity Decrypt()

// UnityExtensions.EncryptionExtensions
public static string Decrypt(this string cipherString)
{
    string result = string.Empty;
    try
    {
        byte[] array = Convert.FromBase64String(cipherString);
        EncryptionExtensions.ValidateInput(cipherString);
        EncryptionExtensions.ValidateInput(EncryptionExtensions.SecurityKey);
        byte b = array[0];
        byte b2 = array[array.Length - 1];
        byte[] array2 = new byte[(int)b2];
        int num = (int)(b2 + 1);
        Buffer.BlockCopy(array, array.Length - num, array2, 0, (int)b2);
        byte[] array3 = new byte[array.Length - 1 - (int)b2 - 1];
        Buffer.BlockCopy(array, 1, array3, 0, array3.Length);
        byte[] bytes = Encoding.UTF8.GetBytes(EncryptionExtensions.SecurityKey);
        byte[] array4 = new byte[bytes.Length + 1];
        Buffer.BlockCopy(bytes, 0, array4, 0, bytes.Length);
        array4[array4.Length - 1] = b;
        SHA1CryptoServiceProvider sHA1CryptoServiceProvider = new SHA1CryptoServiceProvider();
        byte[] key = sHA1CryptoServiceProvider.ComputeHash(array4);
        Array.Resize<byte>(ref key, 16);
        sHA1CryptoServiceProvider.Clear();
        TripleDESCryptoServiceProvider tripleDESCryptoServiceProvider = new TripleDESCryptoServiceProvider();
        tripleDESCryptoServiceProvider.Key = key;
        tripleDESCryptoServiceProvider.IV = array2;
        tripleDESCryptoServiceProvider.Mode = CipherMode.CFB;
        tripleDESCryptoServiceProvider.Padding = PaddingMode.PKCS7;
        ICryptoTransform cryptoTransform = tripleDESCryptoServiceProvider.CreateDecryptor();
        byte[] bytes2 = cryptoTransform.TransformFinalBlock(array3, 0, array3.Length);
        tripleDESCryptoServiceProvider.Clear();
        result = Encoding.UTF8.GetString(bytes2);
    }
    catch (Exception var_14_11D)
    {
        return "-1";
    }
    return result;
}