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问如何使用FileStreams的Strings对函数进行重新编码
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Stack Overflow用户

提问于 2019-05-07 07:26:18

回答 2查看 68关注 0票数 1

我正在构建一个需要加密保存等的游戏，所以我做了一些功能来帮助我加密它们。但是，我目前拥有的唯一函数是使用FileStreams作为输入和输出，但我希望使用字符串。函数在文件上运行良好，但我在将FileStreams转换为MemoryStreams到字符串时遇到了困难。注意:我已经删除了不相关的代码。OurCodeWorld.GenerateRandomSalt() 100%工作，用FileStream加密进行测试。

完整代码：

Program.cs:

using System;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Threading;


namespace Encryption_test
{

    class Program
    {
        static public string encryptedExtension = ".aes";
        static public string decryptedExtension = ".decrypted";

        static void Main(string[] args)
        {
            string path = Environment.CurrentDirectory;
            Log($"Current path: {path}");
            string filePath = $"{path}/unencrypted.txt";
            string message =
@"Hello world!
This is my message. 1234";

            RunStackOverFlowString();

            //Sleep forever...zzz
            Thread.Sleep(10000);
            Console.WriteLine();

            float TicksToMs(long ticks)
            {
                return ticks / (float)Stopwatch.Frequency * 1000F;
            }

            void RunStackOverFlowString()
            {
                byte[] salt = OurCodeWorld.GenerateRandomSalt();
                int iterations = 1024;
                string password = "";
                string enc = StackOverflow.EncryptString(message, password, salt, iterations);
                Log($"Enc: {enc}");
                string dec = StackOverflow.DecryptString(enc, password, salt, iterations);
                Log($"Dec: {dec}");
            }
        private static void WriteFile(string path, string value)
        {
            FileStream _file = File.OpenWrite(path);
            byte[] info = new UTF8Encoding(true).GetBytes(value);
            _file.Write(info, 0, info.Length);
            _file.Close();
        }

        private static string ReadFile(string filePath, long length = long.MaxValue)
        {
            FileStream _file = File.OpenRead(filePath);
            if (length == long.MaxValue)
                length = _file.Length;

            byte[] b = new byte[length];
            UTF8Encoding temp = new UTF8Encoding(true);

            _file.Read(b, 0, b.Length);
            _file.Close();

            return temp.GetString(b);
        }

        private static void DeleteFile(string path)
        {
            File.Delete(path);
        }
        private static void CreateFile(string path)
        {
            if (File.Exists(path))
                DeleteFile(path);
            FileStream a = File.Open(path, FileMode.Create);
            a.Close();
        }
        static void Log(string message)
        {
            Console.WriteLine(message);
        }
    }
}

StackOverFlow.cs:

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

class StackOverflow
{

    // Rfc2898DeriveBytes constants:

    /// <summary>Decrypt a file.</summary>
    /// <remarks>NB: "Padding is invalid and cannot be removed." is the Universal CryptoServices error.  Make sure the password, salt and iterations are correct before getting nervous.</remarks>
    /// <param name="sourceFilename">The full path and name of the file to be decrypted.</param>
    /// <param name="destinationFilename">The full path and name of the file to be output.</param>
    /// <param name="password">The password for the decryption.</param>
    /// <param name="salt">The salt to be applied to the password.</param>
    /// <param name="iterations">The number of iterations Rfc2898DeriveBytes should use before generating the key and initialization vector for the decryption.</param>
    public static void DecryptFile(string sourceFilename, string destinationFilename, string password, byte[] salt, int iterations)
    {
        AesManaged aes = new AesManaged();
        aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
        aes.KeySize = aes.LegalKeySizes[0].MaxSize;
        // NB: Rfc2898DeriveBytes initialization and subsequent calls to   GetBytes   must be eactly the same, including order, on both the encryption and decryption sides.
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(password, salt, iterations);
        aes.Key = key.GetBytes(aes.KeySize / 8);
        aes.IV = key.GetBytes(aes.BlockSize / 8);
        aes.Mode = CipherMode.CBC;
        ICryptoTransform transform = aes.CreateDecryptor(aes.Key, aes.IV);

        using (FileStream destination = new FileStream(destinationFilename, FileMode.Create, FileAccess.Write, FileShare.None))
        {
            using (CryptoStream cryptoStream = new CryptoStream(destination, transform, CryptoStreamMode.Write))
            {
                try
                {
                    using (FileStream source = new FileStream(sourceFilename, FileMode.Open, FileAccess.Read, FileShare.Read))
                    {
                        source.CopyTo(cryptoStream);
                    }
                }
                catch (CryptographicException exception)
                {
                    if (exception.Message == "Padding is invalid and cannot be removed.")
                        throw new ApplicationException("Universal Microsoft Cryptographic Exception (Not to be believed!)", exception);
                    else
                        throw;
                }
            }
        }
    }

    /// <summary>Encrypt a file.</summary>
    /// <param name="sourceFilename">The full path and name of the file to be encrypted.</param>
    /// <param name="destinationFilename">The full path and name of the file to be output.</param>
    /// <param name="password">The password for the encryption.</param>
    /// <param name="salt">The salt to be applied to the password.</param>
    /// <param name="iterations">The number of iterations Rfc2898DeriveBytes should use before generating the key and initialization vector for the decryption.</param>
    public static void EncryptFile(string sourceFilename, string destinationFilename, string password, byte[] salt, int iterations)
    {
        AesManaged aes = new AesManaged();
        aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
        aes.KeySize = aes.LegalKeySizes[0].MaxSize;
        // NB: Rfc2898DeriveBytes initialization and subsequent calls to   GetBytes   must be eactly the same, including order, on both the encryption and decryption sides.
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(password, salt, iterations);
        aes.Key = key.GetBytes(aes.KeySize / 8);
        aes.IV = key.GetBytes(aes.BlockSize / 8);
        aes.Mode = CipherMode.CBC;
        ICryptoTransform transform = aes.CreateEncryptor(aes.Key, aes.IV);

        using (FileStream destination = new FileStream(destinationFilename, FileMode.Create, FileAccess.Write, FileShare.None))
        {
            using (CryptoStream cryptoStream = new CryptoStream(destination, transform, CryptoStreamMode.Write))
            {
                using (FileStream source = new FileStream(sourceFilename, FileMode.Open, FileAccess.Read, FileShare.Read))
                {
                    source.CopyTo(cryptoStream);
                }
            }
        }
    }

    //THIS IS MY CODE
    public static string EncryptString(string inputString, string password, byte[] salt, int iterations)
    {
        AesManaged aes = new AesManaged();
        aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
        aes.KeySize = aes.LegalKeySizes[0].MaxSize;
        // NB: Rfc2898DeriveBytes initialization and subsequent calls to   GetBytes   must be eactly the same, including order, on both the encryption and decryption sides.
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(password, salt, iterations);
        aes.Key = key.GetBytes(aes.KeySize / 8);
        aes.IV = key.GetBytes(aes.BlockSize / 8);
        aes.Mode = CipherMode.CBC;
        ICryptoTransform transform = aes.CreateEncryptor(aes.Key, aes.IV);

        var source = StringToStream(inputString);
        var output = new MemoryStream();

        CryptoStream cryptoStream = new CryptoStream(output, transform, CryptoStreamMode.Write);
        source.CopyTo(cryptoStream);
        return StreamToString(output);
    }

    public static string DecryptString(string inputString, string password, byte[] salt, int iterations)
    {
        AesManaged aes = new AesManaged();
        aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
        aes.KeySize = aes.LegalKeySizes[0].MaxSize;
        // NB: Rfc2898DeriveBytes initialization and subsequent calls to   GetBytes   must be eactly the same, including order, on both the encryption and decryption sides.
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(password, salt, iterations);
        aes.Key = key.GetBytes(aes.KeySize / 8);
        aes.IV = key.GetBytes(aes.BlockSize / 8);
        aes.Mode = CipherMode.CBC;
        ICryptoTransform transform = aes.CreateDecryptor(aes.Key, aes.IV);

        var source = StringToStream(inputString);
        var output = new MemoryStream();

        CryptoStream cryptoStream = new CryptoStream(output, transform, CryptoStreamMode.Write);
        source.CopyTo(cryptoStream);
        return StreamToString(output);
    }


    public static Stream StringToStream(string s)
    {
        var stream = new MemoryStream();
        var writer = new StreamWriter(stream);
        writer.Write(s);
        writer.Flush();
        stream.Position = 0;
        return stream;
    }
    public static string StreamToString(Stream s)
    {
        s.Position = 0;
        byte[] buffer = new byte[s.Length];
        s.Read(buffer, 0, (int)s.Length);
        return Encoding.Default.GetString(buffer);
    }
}

我已经测试了StreamToString和StringToStream方法，它们工作得很好。当我运行DecryptString时，没有输出，该函数返回乱码字符串，通常看起来类似于这个Dec: ?K??? ?@?????n?l?r????T?。

string

encryption

stream

aes

回答 2

Stack Overflow用户

回答已采纳

发布于 2019-05-07 08:27:39

我测试了密码。有两个问题：

您使用加密的字节并使用编码将它们转换为字符串。这个过程通常会失败，因为您不能接受任意字节并将它们转换为字符串。字节和字符串之间的映射不是1:1。很可能，这里根本不应该使用字符串。相反，将数据保持为字节格式，并将这些字节写入文件。方法签名应该类似于byte[] Encrypt(byte[] input, ...)。加密代码不需要从字符串转换到字符串。
EncryptString必须使用FlushFinalBlock刷新密码流。如果没有这样做，数据在结尾将丢失。

票数 0

Stack Overflow用户

发布于 2019-05-07 08:06:35

字符串和二进制数据之间的转换是用和Encoding完成的。编码决定如何将字符转换为二进制数据。常见的封装是Unicode、UTF8或ASCII。如果您想要可预测的结果，则需要对这两种转换使用特定的编码。

在StringToStream中，您根本不指定编码，而在StreamToString中使用Encoding.Default。Encoding.Default不提供可预测的结果，因为它使用当前代码页(如果您在Windows上运行)。因此，您不能确定在这两种方法中都使用了相同的编码。

解决方案是在两端提供相同的编码：

public static Stream StringToStream(string s)
{
    byte[] buffer = Encoding.UTF8.GetBytes(s);
    return new MemoryStream(buffer);
}

public static string StreamToString(Stream s)
{
    s.Position = 0;
    byte[] buffer = new byte[s.Length];
    s.Read(buffer, 0, (int)s.Length);
    return Encoding.UTF8.GetString(buffer);
}

票数 0

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/56017544

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