便携式类库（PCL）贡献 - 密码学

Question

我想在codeplex上的Portable Class Library Contrib项目中使用加密，但是没有找到关于如何使用它的任何文档。

我想在其中创建一个包含Encrypt和Decrypt方法的包装类，我希望这个包装类存在于可移植类库中。 我在这个项目中引用了Portable.Runtime和Portable.Security.Cryptography 。 它是否正确？

然后我想在.NET，Windows Phone和Metro项目中使用我的包装器。 在这些项目中，我引用了我的包装器项目， Portable.Runtime ， Portable.Security.Cryptography和相应的Portable项目，即Portable.Desktop ， Portable.Phone或Portable.WindowsStore 。 它是否正确？

但是当我尝试使用我的包装器类时，我遇到了冲突的命名空间错误。 这是错误和我的包装类：

System.Security.Cryptography.AesManaged类型存在于C:\\Program Files (x86)\\Reference Assemblies\\Microsoft\\Framework\\.NETFramework\\v4.0\\Profile\\Client\\System.Core.dll和C:\\Downloads\\PclContrib\\bin\\Debug\\Portable.Security.Cryptography.dll

public sealed class SymmetricCryptography<T> where T : SymmetricAlgorithm, new()
{
    private readonly T provider = new T();
    private readonly UTF8Encoding utf8 = new UTF8Encoding();

    private byte[] key;
    private byte[] iv;

    public byte[] Key
    {
        get { return this.key; }
    }

    public byte[] IV
    {
        get { return this.iv; }
    }

    public SymmetricCryptography()
    {
        this.key = this.provider.Key;
        this.iv = this.provider.IV;
    }

    public SymmetricCryptography(byte[] key, byte[] iv)
    {
        this.key = key;
        this.iv = iv;
    }

    public SymmetricCryptography(string password, string salt)
    {
        Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(password, this.utf8.GetBytes(salt));
        this.key = deriveBytes.GetBytes(this.provider.KeySize >> 3);
        this.iv = deriveBytes.GetBytes(16);
    }

    public SymmetricCryptography(string password, string salt, int iterations)
    {
        Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes(password, this.utf8.GetBytes(salt), iterations);
        this.key = deriveBytes.GetBytes(this.provider.KeySize >> 3);
        this.iv = deriveBytes.GetBytes(16);
    }

    public byte[] Encrypt(byte[] input)
    {
        return this.Encrypt(input, this.key, this.iv);
    }

    public byte[] Encrypt(byte[] input, byte[] key, byte[] iv)
    {
        return this.Transform(
            input,
            this.provider.CreateEncryptor(key, iv));
    }

    public byte[] Decrypt(byte[] input)
    {
        return this.Decrypt(input, this.key, this.iv);
    }

    public byte[] Decrypt(byte[] input, byte[] key, byte[] iv)
    {
        return this.Transform(
            input,
            this.provider.CreateDecryptor(key, iv));
    }

    public string Encrypt(string text)
    {
        return this.Encrypt(text, this.key, this.iv);
    }

    public string Encrypt(string text, byte[] key, byte[] iv)
    {
        byte[] output = this.Transform(
            this.utf8.GetBytes(text),
            this.provider.CreateEncryptor(key, iv));
        return Convert.ToBase64String(output);
    }

    public string Decrypt(string text)
    {
        return this.Decrypt(text, this.key, this.iv);
    }

    public string Decrypt(string text, byte[] key, byte[] iv)
    {
        byte[] output = this.Transform(
            Convert.FromBase64String(text),
            this.provider.CreateDecryptor(key, iv));
        return this.utf8.GetString(output, 0, output.Length);
    }

    public void Encrypt(Stream input, Stream output)
    {
        this.Encrypt(input, output, this.key, this.iv);
    }

    public void Encrypt(Stream input, Stream output, byte[] key, byte[] iv)
    {
        this.TransformStream(true, ref input, ref output, key, iv);
    }

    public void Decrypt(Stream input, Stream output)
    {
        this.Decrypt(input, output, this.key, this.iv);
    }

    public void Decrypt(Stream input, Stream output, byte[] key, byte[] iv)
    {
        this.TransformStream(false, ref input, ref output, key, iv);
    }

    private byte[] Transform(
        byte[] input,
        ICryptoTransform cryptoTransform)
    {
        byte[] result;

        using (MemoryStream memoryStream = new MemoryStream())
        {
            using (CryptoStream cryptStream = new CryptoStream(
                memoryStream,
                cryptoTransform,
                CryptoStreamMode.Write))
            {
                cryptStream.Write(input, 0, input.Length);
                cryptStream.FlushFinalBlock();
                memoryStream.Position = 0;
                result = memoryStream.ToArray();
            }
        }

        return result;
    }

    private void TransformStream(bool encrypt, ref Stream input, ref Stream output, byte[] key, byte[] iv)
    {
        // defensive argument checking
        if (input == null)
        {
            throw new ArgumentNullException("input");
        }

        if (output == null)
        {
            throw new ArgumentNullException("output");
        }

        if (!input.CanRead)
        {
            throw new ArgumentException("Unable to read from the input Stream.", "input");
        }

        if (!output.CanWrite)
        {
            throw new ArgumentException("Unable to write to the output Stream.", "output");
        }

        // make the buffer just large enough for 
        // the portion of the stream to be processed
        byte[] inputBuffer = new byte[input.Length - input.Position];
        // read the stream into the buffer
        input.Read(inputBuffer, 0, inputBuffer.Length);
        // transform the buffer
        byte[] outputBuffer = encrypt ? Encrypt(inputBuffer, key, iv)
                                        : Decrypt(inputBuffer, key, iv);
        // write the transformed buffer to our output stream 
        output.Write(outputBuffer, 0, outputBuffer.Length);
    }
}

Answer 1

文档有点缺乏，但我在常见问题中称之为：

我可以与我的平台特定项目共享PclContrib中的类型吗？ 不，不是。 虽然PclContrib中的类型看起来和感觉像是特定于平台的对应物，但运行时和编译器会将它们视为完全不同的类型。 虽然我们对如何使这项工作有一些想法，但这是我们短期内不会考虑的功能。

Answer 2

以下.net代码适用于桌面实现。 首先添加对Portable.Desktop和Portable.Security.Cryptography.ProtectedData的引用

   private void button2_Click(object sender, EventArgs e)
    {
        String encrypted = PCL.CentralClass.Encrypt("yo");
        String decreypted = PCL.CentralClass.Decrypt(encrypted);
        //PCL.CentralClass.
    }
    //https://pclcontrib.codeplex.com/documentation?FocusElement=Comment
    //\Source\Portable.Security.Cryptography.ProtectedData\Security\Cryptography\ProtectedData.cs

    static byte[] GetBytes(string str)
    {
        byte[] bytes = new byte[str.Length * sizeof(char)];
        System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
        return bytes;
    }

    static string GetString(byte[] bytes)
    {
        char[] chars = new char[bytes.Length / sizeof(char)];
        System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
        return new string(chars);
    }

    public static String Encrypt(String strEncrypt)
    {
        byte[] userData = GetBytes(strEncrypt);
        byte[] optionalEntropy = null;
        byte[] x = System.Security.Cryptography.ProtectedData.Protect(userData, optionalEntropy);
        return GetString(x);
    }
    public static String Decrypt(String strDecrypt)
    {
        byte[] encryptedData = GetBytes(strDecrypt);
        byte[] optionalEntropy = null;
        byte[] x = System.Security.Cryptography.ProtectedData.Unprotect(encryptedData, optionalEntropy);
        return GetString(x); ;
    }

Answer 3

事实证明，我的密码算法的通用包装器导致了一个问题。 PCL Contrib包含一个名为SymmetricAlgorithm的类，它本身就是真正的SymmetricAlgorithm的包装器。 如果我使我的包装类非泛型它的工作方式如下：

public sealed class AesManagedSymmetricCryptography : SymmetricCryptography<AesManaged>
{
    #region Constructors

    public AesManagedSymmetricCryptography()
    {
    }

    public AesManagedSymmetricCryptography(byte[] key, byte[] iv)
        : base(key, iv)
    {
    }

    public AesManagedSymmetricCryptography(string password, string salt)
        : base(password, salt)
    {
    }

    public AesManagedSymmetricCryptography(string password, string salt, int iterations)
        : base(password, salt, iterations)
    {
    }

    #endregion
}