二进制格式化程序反序列化时CryptoStream问题

Question

我在这里有点绝望了。我正在尝试将带有序列化对象的加密文件写入磁盘，然后检索该文件，解密该文件并将对象反序列化回来。

更新： 我将代码重构为：

using (Stream innerStream = File.Create(this.GetFullFileNameForUser(securityContext.User, applicationName)))
            {
                using (Stream cryptoStream = new CryptoStream(innerStream, GetCryptoProvider().CreateEncryptor(), CryptoStreamMode.Write))
                {
                    // 3. write to the cryptoStream 
                    //BinaryFormatter bf = new BinaryFormatter();
                    //bf.Serialize(cryptoStream, securityContext);
                    XmlSerializer xs = new XmlSerializer(typeof(SecurityContextDTO));
                    xs.Serialize(cryptoStream, securityContext);
                }
            }


 using (Stream innerStream = File.Open(this.GetFullFileNameForUser(user, applicationName), FileMode.Open))
        {
            using (Stream cryptoStream = new CryptoStream(innerStream, GetCryptoProvider().CreateDecryptor(), CryptoStreamMode.Read))
            {
                //BinaryFormatter bf = new BinaryFormatter();
                //return (SecurityContextDTO)bf.Deserialize(cryptoStream);
                XmlSerializer xs = new XmlSerializer(typeof(SecurityContextDTO));
                //CryptographicException here
                return (SecurityContextDTO)xs.Deserialize(cryptoStream);
            }
        }

现在我在反序列化时遇到加密异常：错误数据

原始：

我正在这样做：

public void StoreToFile(SecurityContextDTO securityContext, string applicationName)
    {
        if (securityContext.LoginResult.IsOfflineMode == false)
        {
            Stream stream = null;
            CryptoStream crStream = null;
            try
            {
                TripleDESCryptoServiceProvider cryptic = GetCryptoProvider();

                stream = File.Open(this.GetFullFileNameForUser(securityContext.User, applicationName), FileMode.Create);
                crStream = new CryptoStream(stream,
                   cryptic.CreateEncryptor(), CryptoStreamMode.Write);

                BinaryFormatter bFormatter = new BinaryFormatter();
                bFormatter.Serialize(crStream, securityContext);
            }
            catch(Exception)
            {
                throw;
            }
            finally
            {
                if (crStream != null)
                    crStream.Close();
            }
        }
    }



public SecurityContextDTO RetrieveFromFile(UserDTO user,string applicationName)
    {
        SecurityContextDTO objectToSerialize;
        Stream stream = null;
        CryptoStream crStream=null;
        try
        {
            stream = File.Open(this.GetFullFileNameForUser(user, applicationName), FileMode.Open);
             crStream= new CryptoStream(stream,
                GetCryptoProvider().CreateDecryptor(), CryptoStreamMode.Read);
            BinaryFormatter bFormatter = new BinaryFormatter();
            //Exception here
            objectToSerialize = (SecurityContextDTO)bFormatter.Deserialize(crStream); 
        }
        catch (Exception)
        {
            objectToSerialize = null;
        }
        finally
        {
            if (crStream!=null)
                crStream.Close();
        }
        return objectToSerialize;
    }


private static TripleDESCryptoServiceProvider GetCryptoProvider()
    {
        TripleDESCryptoServiceProvider cryptic = new TripleDESCryptoServiceProvider();
        try
        {
            cryptic.Key = ASCIIEncoding.ASCII.GetBytes(CrypKey);

            Rfc2898DeriveBytes db = new Rfc2898DeriveBytes("sdddsdsd", 8);
            cryptic.IV = db.GetBytes(8);
        }
        catch (Exception)
        {
            throw;
        }
        finally
        {
            cryptic.Dispose();
        }
        return cryptic;
    }

加密和写入工作正常，文件出现在磁盘上并且内容在那里（当然是加密的） 。但是当我调用检索方法时，我总是得到 SerializationException

二进制流“30”不包含有效的 BinaryHeader。可能的原因是序列化和反序列化之间无效的流或对象版本更改。

当我将加密方法排除在外时，一切正常。

Answer 1

所以，

您意识到在这段代码中

private static TripleDESCryptoServiceProvider GetCryptoProvider()
{
    TripleDESCryptoServiceProvider cryptic = new TripleDESCryptoServiceProvider();
    try
    {
        cryptic.Key = ASCIIEncoding.ASCII.GetBytes(CrypKey);

        Rfc2898DeriveBytes db = new Rfc2898DeriveBytes("sdddsdsd", 8);
        cryptic.IV = db.GetBytes(8);
    }
    catch (Exception)
    {
        throw;
    }
    finally
    {
        cryptic.Dispose(); // <------- Don't do this until you are done decrypting.
    }
    return cryptic;
}

您将始终处置提供程序，这意味着您始终使用随机密钥和 iv

Answer 2

你很接近。但是，您传递到 CryptoStream 创建中的流始终、始终、始终是将保存最终结果的缓冲区。它不是保存您想要加密或解密的数据的流。我把重点放在那里是因为我记得第一次学习这个并且我完全按照你在做的事情做。所以这里：

// this is for encryption
var memStreamEncryptedData = new MemoryStream();
var encryptStream = new CryptoStream(memStreamEncryptedData, 
   transform, CryptoStreamMode.Write);

// this is for decryption
var memStreamDecryptedData = new MemoryStream();
var decryptStream = new CryptoStream(memStreamDecryptedData, 
   transform, CryptoStreamMode.Write);

请注意，在这两种情况下，CryptoStream 都是用空白输出流初始化的。您的流要稍后才会进入画面。因此，在写入期间，您将执行以下操作：

encryptStream.Write(dataToBeEncrypted);
encryptStream.FlushFinalBlock();
encryptStream.Close();
// memStreamEncryptedData now safely holds your encrypted data

在读取期间，您将：

decryptStream.Write(dataToBeDecrypted);
encryptStream.FlushFinalBlock();
encryptStream.Close();
// memStreamDecryptedData now safely holds your decrypted data

因此，为了省去一些麻烦，这里有一个很好的简单对称方法，它将执行加密和解密。这和你的唯一区别是我直接在字节数组上工作，但也许这种增强可以是一种练习：

public static byte[] Symmetric(bool encrypt, byte[] plaintext, string ikey)
{
    if (plaintext.Length == 0) return plaintext;

    // setting up the services can be very expensive, so I'll cache them
    // into a static dictionary.
    SymmetricSetup setup;
    if (!_dictSymmetricSetup.TryGetValue(ikey, out setup))
    {
        setup = new SymmetricSetup();
        setup.des = new DESCryptoServiceProvider { Mode = CipherMode.CBC, 
            Padding = PaddingMode.Zeros };
        setup.hash = Hash(Encoding.ASCII.GetBytes(ikey));
        setup.key = setup.hash.ForceLength(8, 0);
        setup.IV = Encoding.ASCII.GetBytes("init vec");
        setup.des.Key = setup.key;
        setup.des.IV = setup.IV;

        setup.encrypt = setup.des.CreateEncryptor(setup.des.Key, setup.des.IV);
        setup.decrypt = setup.des.CreateDecryptor(setup.des.Key, setup.des.IV);
        _dictSymmetricSetup[ikey] = setup;
    }

    var transform = encrypt ? setup.encrypt : setup.decrypt;

    var memStreamEncryptedData = new MemoryStream();

    var encStream = new CryptoStream(memStreamEncryptedData, transform, CryptoStreamMode.Write);

    if (encrypt)
        encStream.Write(new[] {(byte) ((8 - (plaintext.Length + 1)%8)%8)}, 0, 1);

    encStream.Write(plaintext, 0, plaintext.Length);
    encStream.FlushFinalBlock();
    encStream.Close();

    memStreamEncryptedData.Flush();

    var ciphertext = memStreamEncryptedData.ToArray();

    byte b;

    if (!encrypt)
        if (byte.TryParse("" + ciphertext[0], out b))
            ciphertext = ciphertext.Skip(1).Take(ciphertext.Length - b - 1).ToArray();

    return ciphertext;
}

并且要调用它，你可能会做这样的事情：

static public byte[] DecryptData(this byte[] source, string password) {
    return Symmetric(false, source, password);
}

static public byte[] EncryptData(this byte[] source, string password) {
    return Symmetric(true, source, password);
}

同样，你会做一些稍微不同的事情来使用流，但希望你能明白要点。它将是您需要输入序列化器的任何流，而不是 MemoryStream。

Answer 3

以前的一些帖子可以使用：

如何使用 RijndaelManaged 和 PKCS5 加密 vb.net 中的字符串填充？

BinaryFormatter是否应用任何压缩？

稍后，您可以看到我如何将压缩、加密和序列化叠加起来。它有效。