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？

Base64是二进制到文本编码.它将字节编码为文本.

在这种情况下你需要后者.

Encoding.UTF8.GetString解码一个UTF-8编码的字节数组,如果存在无效的字节序列(这很有可能是像密文一样给它随机字节),那么它是有损的.

在以下示例中,myOriginalBytes和asBytes不相等,即使它们的长度不同.谁能解释我错过了什么？

byte[] myOriginalBytes = GetRandomByteArray();
var asstring = Encoding.UTF8.GetString(myOriginalBytes);
var asBytes = Encoding.UTF8.GetBytes(asstring);

让我们来看一个具体而简单的例子：单个字节0xff.这不是任何文本的有效UTF-8编码.所以如果你有：

byte[] bytes = { 0xff };
string text = Encoding.UTF8.GetString(bytes);

…你最终将文本作为单个字符,U+FFFD,“Unicode替换字符”,用于表示解码二进制数据时出错.对于任何无效序列,您最终会得到替换字符 – 例如,如果以0x80开头,则会获得相同的文本.显然,如果多个二进制输入被解码为相同的文本输出,则它不可能是完全可逆的变换.

如果您有任意二进制数据,则不应使用Encoding从中获取文本 – 您应该使用Convert.ToBase64String或者hex.编码用于自然文本的数据.

如果你走向相反的方向,像这样：

string text = GetRandomText();
byte[] bytes = Encoding.UTF8.GetBytes(text);
string text2 = Encoding.UTF8.GetString(bytes);

…我希望text2等于文本,除了你有无效文本的奇怪情况,例如与“一半”代理对.