C# 字节[] 加密

Question

我有一个 Byte[] 字段，它是我需要加密的文件内容。没有什么特别或花哨的，只是足以确保下一个得到它的人不费吹灰之力就无法轻松解码它。我会使用 .Net Framework 4.0 附带的加密，但我绝对不需要让文件变得比实际更大。

我想过只是简单地反转数组或在末尾添加几个字节......？

如果我可以避免使数组变得更大，那就太好了。

有什么建议吗？

谢谢！

Answer 1

增加 1-16 个字节有影响吗？默认情况下，AES 将使用以下方法填充：

    private static void EncryptThenDecrypt(byte[] msg)
    {
        byte[] message = msg; // fill with your bytes

        if (message is null)
        {
            return;
        }

        byte[] encMessage; // the encrypted bytes
        byte[] decMessage; // the decrypted bytes - s/b same as message
        byte[] key;
        byte[] iv;

        using (SymmetricAlgorithm aes = Aes.Create())
        {
            if (aes is null)
            {
                iv = key = null;
                encMessage = Array.Empty<byte>();
            }
            else
            {
                aes.GenerateKey();
                aes.GenerateIV();
                key = aes.Key;
                iv = aes.IV;
                encMessage = EncryptBytes(aes, message);
            }
        }

        using (SymmetricAlgorithm aes = Aes.Create())
        {
            if (aes is null || key is null)
            {
                decMessage = Array.Empty<byte>();
            }
            else
            {
                aes.Key = key;
                aes.IV = iv;
                decMessage = DecryptBytes(aes, encMessage);
            }
        }

        Debug.Assert(message.SequenceEqual(decMessage), "Decrypted bytes do not match original bytes.");
    }

    private static byte[] EncryptBytes(SymmetricAlgorithm alg, byte[] message)
    {
        if (message is null)
        {
#pragma warning disable S1168 // Empty arrays and collections should be returned instead of null
            return null;
#pragma warning restore S1168 // Empty arrays and collections should be returned instead of null
        }

        if (message.Length == 0)
        {
            return message;
        }

        if (alg is null)
        {
            throw new ArgumentNullException(nameof(alg));
        }

        using (MemoryStream stream = new MemoryStream())
        using (ICryptoTransform encryptor = alg.CreateEncryptor())
        using (CryptoStream encrypt = new CryptoStream(stream, encryptor, CryptoStreamMode.Write))
        {
            encrypt.Write(message, 0, message.Length);
            encrypt.FlushFinalBlock();
            return stream.ToArray();
        }
    }

    private static byte[] DecryptBytes(SymmetricAlgorithm alg, byte[] message)
    {
        if (message is null)
        {
#pragma warning disable S1168 // Empty arrays and collections should be returned instead of null
            return null;
#pragma warning restore S1168 // Empty arrays and collections should be returned instead of null
        }

        if (message.Length == 0)
        {
            return message;
        }

        if (alg is null)
        {
            throw new ArgumentNullException(nameof(alg));
        }

        using (MemoryStream stream = new MemoryStream())
        using (ICryptoTransform decryptor = alg.CreateDecryptor())
        using (CryptoStream encrypt = new CryptoStream(stream, decryptor, CryptoStreamMode.Write))
        {
            encrypt.Write(message, 0, message.Length);
            encrypt.FlushFinalBlock();
            return stream.ToArray();
        }
    }

Answer 2

不要发明自己的加密机制（即通过混淆实现安全性），请使用classes provided by the framework 之一。