AES加密的C＃UTF8编码问题

Question

我正在创建一个基于TCP的聊天客户端。我正在尝试使用AES加密某些数据（以提高安全性）我有一个AES加密类，默认情况下它使用UTF-8作为输出和输入的编码类型。但是由于某种原因，当我通过TCPClient（使用UTF-8）传递信息并从另一端获取信息时，它会抛出错误：

`System.Security.Cryptography.CryptographicException: Length of the data to decrypt is invalid.
   at System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
   at System.Security.Cryptography.CryptoStream.FlushFinalBlock()`

因此，我在不使用TCP客户端的情况下重新创建了问题，只是将AES加密的数据放入UTF-8编码系统中，该系统获取字节数组的字符串，然后使用UTF-8重新获取字节数组（基本上是与网络上发生的事情相同（没有字符串））

此方法有效：

        string dataToEncrypt = "Hello World";
        byte[] key = Encryption.AesEncryption.GenerateKey(32);
        byte[] iv = Encryption.AesEncryption.GenerateKey(16);

        byte[] encrypted = Encryption.AesEncryption.EncryptString(dataToEncrypt, key, iv);

        string decrypted = Encryption.AesEncryption.DecryptedBytes(encrypted, key, iv);

该方法不起作用（从上面抛出错误）

        Encoding encoding = Encoding.UTF8;

        string dataToEncrypt = "Hello World";
        byte[] key = Encryption.AesEncryption.GenerateKey(32);
        byte[] iv = Encryption.AesEncryption.GenerateKey(16);

        byte[] encrypted = Encryption.AesEncryption.EncryptString(dataToEncrypt, key, iv);

        string encstring = encoding.GetString(encrypted);

        byte[] utf8encrypted = encoding.GetBytes(encstring);

        string decrypted = Encryption.AesEncryption.DecryptedBytes(utf8encrypted, key, iv);

我究竟做错了什么？

这是我的加密类：

public sealed class AesEncryption
{
    private byte[] Key;

    public Encoding Encoder = Encoding.UTF8;

    public AesEncryption(byte[] key)
    {
        Key = key;
    }

    public byte[] Encrypt(string text, byte[] iv)
    {
        var bytes = Encoder.GetBytes(text);
        var rm = new RijndaelManaged();
        var encrypter = rm.CreateEncryptor(Key, iv);
        var ms = new MemoryStream();
        var cs = new CryptoStream(ms, encrypter, CryptoStreamMode.Write);
        cs.Write(bytes, 0, bytes.Length);
        cs.FlushFinalBlock();
        var output = ms.ToArray();
        cs.Close();
        ms.Close();
        return output;
    }

    public string Decrypt(byte[] encrypted, byte[] iv)
    {
        var ms = new MemoryStream();
        var cs = new CryptoStream(ms,
            new RijndaelManaged().CreateDecryptor(Key, iv),
            CryptoStreamMode.Write);
        cs.Write(encrypted, 0, encrypted.Length);
        cs.FlushFinalBlock();
        var output = ms.ToArray();
        cs.Close();
        ms.Close();
        return Encoder.GetString(output);
    }

    public static byte[] EncryptString(string text, byte[] key, byte[] iv)
    {
        var ec = new AesEncryption(key);
        return ec.Encrypt(text, iv);
    }

    public static string DecryptedBytes(byte[] encrypted, byte[] key, byte[] iv)
    {
        var ec = new AesEncryption(key);
        return ec.Decrypt(encrypted, iv);
    }

    public static byte[] GenerateKey(int length)
    {
        Random rnd = new Random();

        var chars = "1!2@3#4$5%6^7&8*9(0)-_=+qQwWeErRtTyYuUiIoOpP[{]}\\|aAsSdDfFgGhHjJkKlL;:'\"zZxXcCvVbBnNmM,<.>/?".ToCharArray();

        string randomizedKey = "";

        for (int i = 0; i < length; i++)
        {
            randomizedKey += chars[rnd.Next(0, chars.Length)];
        }
        return randomizedKey.ToByteArray();
    }
}

Answer 1

UTF-8 不能完美地表示字节。简短而简单的答案是：传输字节，而不是 UTF-8 字符串。如果您必须有一个字符串，请使用 Base64 对其进行编码。