C# Rijndael 加密将额外的字节放在解密文件的前面

Question

我正在尝试使用 Rijndael 加密来加密图像文件，我一定是做错了什么，因为解密的文件在文件的前面带有额外的数据，最后可能还有一点额外的数据。我对这种加密算法还很陌生，所以我很确定我只是遗漏了一些简单的东西。

使用文本文件的示例

输入文件

"the quick brown fox jumped over the lazy yellow dog"

当我尝试将生成的 IV 放在文件前面时的输出文件 (\0=null)

"ÚñjÐæƒÊW®ï¡_Ü&ßthe\0 quick brown fox jumped over the lazy yellow dog"

当我尝试将等于我的 key 的 IV 放在前面时的输出文件

"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0the\0\0\0\0\0\0 quick brown fox jumped over the lazy yellow dog"

当我使用与我的 key 相同的 IV 并且在文件前面不放置任何内容时的输出文件

"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0the\0\0\0\0\0\0 quick brown fox jumped over the lazy yellow dog"

代码

private RijndaelManaged GetCipher(byte[] key, bool forEncrypt)
{
    RijndaelManaged rijndaelCipher;

    rijndaelCipher = new RijndaelManaged();
    rijndaelCipher.Mode = CipherMode.CBC;
    rijndaelCipher.Padding = PaddingMode.PKCS7;
    rijndaelCipher.KeySize = 0x80;
    rijndaelCipher.BlockSize = 0x80;
    rijndaelCipher.Key = key;

   /* if (forEncrypt)
        rijndaelCipher.GenerateIV();
    else
    rijndaelCipher.IV = new byte[16];*/
    rijndaelCipher.IV = _imageKey;

    return rijndaelCipher;
}

public void DecryptStamp(Stamp stampToDecrypt, string decrpytedStampFilePath)
{
    RijndaelManaged rijndaelCipher;
    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block;
    int numberRead;
    ICryptoTransform transform;

    if (!File.Exists(stampToDecrypt.Path))
        throw new FileNotFoundException(stampToDecrypt.Path + " does not exist");

    rijndaelCipher = this.GetCipher(_imageKey, false);
    block = new byte[16];

    try
    {
        inputStream = File.Open(stampToDecrypt.Path, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(decrpytedStampFilePath, FileMode.Create, FileAccess.Write);

        //inputStream.Read(rijndaelCipher.IV, 0, rijndaelCipher.IV.Length);
        transform = rijndaelCipher.CreateDecryptor();                     
        encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write);

        while ((numberRead = inputStream.Read(block, 0, block.Length)) > 0)
        {
            Console.WriteLine(numberRead.ToString());
            encryptSteam.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }
}

public Stamp EncryptStampToStampFolder(string stampFileToEncrpyt)
{
    Configuration config;
    Stamp stampToEncrypt;
    RijndaelManaged rijndaelCipher;
    string encryptedFilePath;

    if (!File.Exists(stampFileToEncrpyt))
        throw new FileNotFoundException(stampFileToEncrpyt + " does not exist");

    config = Configuration.GetProgramInstance();
    encryptedFilePath = Path.Combine(config.StampFolder, Path.GetFileNameWithoutExtension(stampFileToEncrpyt) + ".stmp");

    stampToEncrypt = new Stamp(Path.GetFileNameWithoutExtension(stampFileToEncrpyt), encryptedFilePath);

    rijndaelCipher = this.GetCipher(_imageKey, true);
    ICryptoTransform transform = rijndaelCipher.CreateEncryptor();

    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block = new byte[16];
    int numberRead;

    try
    {
        inputStream = File.Open(stampFileToEncrpyt, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(encryptedFilePath, FileMode.Create, FileAccess.Write);

        //outputStream.Write(rijndaelCipher.IV, 0, 16);
        encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write);

        encryptSteam.Write(block, 0, block.Length);

        while ((numberRead = inputStream.Read(block, 0, block.Length)) > 0)
        {
            encryptSteam.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }

    return stampToEncrypt;
}

public struct Stamp
{
    public string Name,
        Path;

    public Stamp(string StampName, string StampPath)
    {
        Name = StampName;
        Path = StampPath;
    }
}

代码修复后

private RijndaelManaged GetCipher(byte[] key, bool forEncrypt)
{
    RijndaelManaged rijndaelCipher;

    rijndaelCipher = new RijndaelManaged();
    rijndaelCipher.Mode = CipherMode.CBC;
    rijndaelCipher.Padding = PaddingMode.PKCS7;
    rijndaelCipher.KeySize = 0x80;
    rijndaelCipher.BlockSize = 0x80;
    rijndaelCipher.Key = key;

    if (forEncrypt)
        rijndaelCipher.GenerateIV();
    else
        rijndaelCipher.IV = new byte[16];
    //rijndaelCipher.IV = _imageKey;

    return rijndaelCipher;
}

public void DecryptStamp(Stamp stampToDecrypt, string decrpytedStampFilePath)
{
    RijndaelManaged rijndaelCipher;
    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block;
    int numberRead;
    ICryptoTransform transform;

    if (!File.Exists(stampToDecrypt.Path))
        throw new FileNotFoundException(stampToDecrypt.Path + " does not exist");

    rijndaelCipher = this.GetCipher(_imageKey, false);
    block = new byte[16];

    try
    {
        inputStream = File.Open(stampToDecrypt.Path, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(decrpytedStampFilePath, FileMode.Create, FileAccess.Write);

        inputStream.Read(rijndaelCipher.IV, 0, rijndaelCipher.IV.Length);
        transform = rijndaelCipher.CreateDecryptor();                     
        encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write);

        while ((numberRead = inputStream.Read(block, 0, block.Length)) > 0)
        {                
            encryptSteam.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }
}

public Stamp EncryptStampToStampFolder(string stampFileToEncrpyt)
{
    Configuration config;
    Stamp stampToEncrypt;
    RijndaelManaged rijndaelCipher;
    string encryptedFilePath;

    if (!File.Exists(stampFileToEncrpyt))
        throw new FileNotFoundException(stampFileToEncrpyt + " does not exist");

    config = Configuration.GetProgramInstance();
    encryptedFilePath = Path.Combine(config.StampFolder, Path.GetFileNameWithoutExtension(stampFileToEncrpyt) + ".stmp");

    stampToEncrypt = new Stamp(Path.GetFileNameWithoutExtension(stampFileToEncrpyt), encryptedFilePath);

    rijndaelCipher = this.GetCipher(_imageKey, true);
    ICryptoTransform transform = rijndaelCipher.CreateEncryptor();

    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block = new byte[16];
    int numberRead;

    try
    {
        inputStream = File.Open(stampFileToEncrpyt, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(encryptedFilePath, FileMode.Create, FileAccess.Write);

        outputStream.Write(rijndaelCipher.IV, 0, 16);
        encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write);

        //encryptSteam.Write(block, 0, block.Length); this line was the problem in the orginal code

        while ((numberRead = inputStream.Read(block, 0, block.Length)) > 0)
        {
            encryptSteam.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }

    return stampToEncrypt;
}

public struct Stamp
{
    public string Name,
        Path;

    public Stamp(string StampName, string StampPath)
    {
        Name = StampName;
        Path = StampPath;
    }
}

新代码的输出

“7p¶¼oò¾½G€¢9±hfox\0\0 跳过懒惰的黄狗”

Answer 1

问题有三方面。1)加密时写入的额外数据2)文件开头的IV被覆盖3)解密时IV没有被正确读取

代码固定

private RijndaelManaged GetCipher(byte[] key, bool forEncrypt)
{
    RijndaelManaged rijndaelCipher;

    rijndaelCipher = new RijndaelManaged();
    rijndaelCipher.Mode = CipherMode.CBC;
    rijndaelCipher.Padding = PaddingMode.PKCS7;
    rijndaelCipher.KeySize = 0x80;
    rijndaelCipher.BlockSize = 0x80;
    rijndaelCipher.Key = key;

    if (forEncrypt)
        rijndaelCipher.GenerateIV();
    else
        rijndaelCipher.IV = new byte[16];
    //rijndaelCipher.IV = _imageKey;

    return rijndaelCipher;
}

public void DecryptStamp(Stamp stampToDecrypt, string decrpytedStampFilePath)
{
    RijndaelManaged rijndaelCipher;
    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block;
    int numberRead;
    ICryptoTransform transform;

    if (!File.Exists(stampToDecrypt.Path))
        throw new FileNotFoundException(stampToDecrypt.Path + " does not exist");

    rijndaelCipher = this.GetCipher(_imageKey, false);
    block = new byte[16];

    try
    {
        inputStream = File.Open(stampToDecrypt.Path, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(decrpytedStampFilePath, FileMode.Create, FileAccess.Write);

        //This line was wrong because rijndaelCipher.IV never filled
        //inputStream.Read(rijndaelCipher.IV, 0, rijndaelCipher.IV.Length); 

        inputStream.Read(block, 0, block.Length);
        rijndaelCipher.IV = block;
        block = new byte[16];
        transform = rijndaelCipher.CreateDecryptor();                     
        encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write);

        while ((numberRead = inputStream.Read(block, 0, block.Length)) > 0)
        {                
            encryptSteam.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }
}

public Stamp EncryptStampToStampFolder(string stampFileToEncrpyt)
{
    Configuration config;
    Stamp stampToEncrypt;
    RijndaelManaged rijndaelCipher;
    string encryptedFilePath;

    if (!File.Exists(stampFileToEncrpyt))
        throw new FileNotFoundException(stampFileToEncrpyt + " does not exist");

    config = Configuration.GetProgramInstance();
    encryptedFilePath = Path.Combine(config.StampFolder, Path.GetFileNameWithoutExtension(stampFileToEncrpyt) + ".stmp");

    stampToEncrypt = new Stamp(Path.GetFileNameWithoutExtension(stampFileToEncrpyt), encryptedFilePath);

    rijndaelCipher = this.GetCipher(_imageKey, true);
    ICryptoTransform transform = rijndaelCipher.CreateEncryptor();

    FileStream inputStream = null;
    FileStream outputStream = null;
    CryptoStream encryptSteam = null;
    byte[] block = new byte[16];
    int numberRead;

    try
    {
        inputStream = File.Open(stampFileToEncrpyt, FileMode.Open, FileAccess.Read);
        outputStream = File.Open(encryptedFilePath, FileMode.Create, FileAccess.Write);

        outputStream.Write(rijndaelCipher.IV, 0, IV.Length);
        //This had to be changed so that the IV was not overwitten
        //encryptSteam = new CryptoStream(outputStream, transform, CryptoStreamMode.Write); 
        encryptSteam = new CryptoStream(inputStream, transform, CryptoStreamMode.Read);

        //this line was a problem in the orginal code that caused extra data to be added to the encrypted file
        //encryptSteam.Write(block, 0, block.Length); 

        while ((numberRead = encryptSteam.Read(block, 0, block.Length)) > 0)
        {
            outputStream.Write(block, 0, numberRead);
        }
    }
    finally
    {
        rijndaelCipher.Clear();
        rijndaelCipher.Dispose();
        if (encryptSteam != null)
            encryptSteam.Dispose();
        if (outputStream != null)
            outputStream.Dispose();
        if (inputStream != null)
            inputStream.Dispose();
    }

    return stampToEncrypt;
}

public struct Stamp
{
    public string Name,
        Path;

    public Stamp(string StampName, string StampPath)
    {
        Name = StampName;
        Path = StampPath;
    }
}