3

我在这里有点绝望。我正在尝试将带有序列化对象的加密文件写入磁盘，然后检索文件，对其进行解密并将对象反序列化。

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了一个加密异常：Bad Data

原来的：

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，我总是得到一个 SerializationException

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

当我离开加密方法时，一切正常。

4

3 回答 3

1

所以，

你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;
}

您将始终处置提供者，这意味着您始终使用随机密钥和 iv

于 2011-08-11T17:21:56.020 回答
0

你很亲密。但是，您传递给 CryptoStream 创建的流始终是保存最终结果的缓冲区。它不是保存您要加密或解密的数据的流。我把重点放在那里，因为我记得第一次学习这个，我做了你正在做的事情。所以在这里：

// 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 都使用空白输出流进行初始化。您的流直到稍后才会进入图片。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

在阅读过程中，您将：

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

所以，为了省点麻烦，这里有一个很好的简单对称方法，可以同时执行加密和解密。这和你的唯一区别是我直接在字节数组上工作，但也许增强可以是一个练习：

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;
}

要调用它，您可能会执行以下操作：

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，您将做一些稍微不同的事情来处理流，但希望您能明白要点。它不是 MemoryStream，而是您需要输入序列化程序的任何流。

于 2011-08-11T16:26:49.613 回答
0

一些以前的帖子可以使用：

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

BinaryFormatter 是否应用任何压缩？

稍后，您可以看到我如何将压缩与加密与序列化叠加在一起。它有效。

于 2011-08-11T17:32:04.313 回答