private byte[] key = Encoding.ASCII.GetBytes("abcdefgh");
    private byte[] IV = Encoding.ASCII.GetBytes("hgfedcba");
    private byte[] encrypted;

    public Form1()
    {
        InitializeComponent();

    }

    private void btnEncrypt_Click(object sender,EventArgs e)
    {
        this.textBox2.Text = this.Encrypt(this.textBox1.Text);
    }

    private void btnDecrypt_Click(object sender,EventArgs e)
    {
        this.textBox3.Text = this.Decrypt(this.textBox2.Text);
    }

    private string Encrypt(string plainText)
    {
        try
        {
            using (DESCryptoServiceProvider crypto = new DESCryptoServiceProvider())
            {
                crypto.Key = this.key;
                crypto.IV = this.IV;

                ICryptoTransform transform = crypto.CreateEncryptor(crypto.Key,crypto.IV);

                using (MemoryStream stream = new MemoryStream())
                {
                    using (CryptoStream cryptoStream = new CryptoStream(stream,transform,CryptoStreamMode.Write))
                    {
                        using (StreamWriter writer = new StreamWriter(cryptoStream))
                        {
                            writer.Write(plainText);
                        }

                        encrypted = stream.ToArray();
                    }
                }
            }

            return Convert.ToBase64String(encrypted);
        }
        catch (Exception)
        {

            throw;
        }
    }

    private string Decrypt(string cipherText)
    {
        try
        {
            string plainText = string.Empty;

            using (DESCryptoServiceProvider crypto = new DESCryptoServiceProvider())
            {
                crypto.Key = this.key;
                crypto.IV = this.IV;

                ICryptoTransform transform = crypto.CreateDecryptor(crypto.Key,crypto.IV);

                using (MemoryStream stream = new MemoryStream(Convert.FromBase64String(cipherText)))
                {
                    using (CryptoStream cryptoStream = new CryptoStream(stream,CryptoStreamMode.Read))
                    {
                        using (StreamReader reader = new StreamReader(cryptoStream))
                        {
                            plainText = reader.ReadToEnd();
                        }
                    }
                }
            }

            return plainText;
        }
        catch (Exception)
        {

            throw;
        }
    }

一切都按预期工作.但如果我更换

return Convert.ToBase64String(encrypted);

和

using (MemoryStream stream = new MemoryStream(Convert.FromBase64String(cipherText)))

至

return Encoding.UTF8.GetString(encrypted);

和

using (MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes(cipherText)))

我在CryptoStream System.NotSupportedException中有错误.在诊断代码之后,我发现Encoding.UTF8.GetBytes(cipherText)具有比加密更多的字节

那么使用Convert.From / ToBase64String和Encoding.UTF8.GetBytes / GetString有什么区别呢？