加密/解密大文件（.NET）-Java 学习之路

我必须加密，存储然后解密大文件 . 这样做的最佳方式是什么？我听说RSA加密很昂贵，建议使用RSA加密AES密钥，然后使用AES密钥加密大文件 . 任何带有示例的建议都会很棒 .

4 回答

这可能有所帮助

/// Encrypts a file using Rijndael algorithm.
///</summary>
///<param name="inputFile"></param>
///<param name="outputFile"></param>
private void EncryptFile(string inputFile, string outputFile)
{

    try
    {
        string password = @"myKey123"; // Your Key Here
        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        string cryptFile = outputFile;
        FileStream fsCrypt = new FileStream(cryptFile, FileMode.Create);

        RijndaelManaged RMCrypto = new RijndaelManaged();

        CryptoStream cs = new CryptoStream(fsCrypt,
            RMCrypto.CreateEncryptor(key, key),
            CryptoStreamMode.Write);

        FileStream fsIn = new FileStream(inputFile, FileMode.Open);

        int data;
        while ((data = fsIn.ReadByte()) != -1)
            cs.WriteByte((byte)data);


        fsIn.Close();
        cs.Close();
        fsCrypt.Close();
    }
    catch
    {
        MessageBox.Show("Encryption failed!", "Error");
    }
}

///
/// Decrypts a file using Rijndael algorithm.
///</summary>
///<param name="inputFile"></param>
///<param name="outputFile"></param>
private void DecryptFile(string inputFile, string outputFile)
{

    {
        string password = @"myKey123"; // Your Key Here

        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        FileStream fsCrypt = new FileStream(inputFile, FileMode.Open);

        RijndaelManaged RMCrypto = new RijndaelManaged();

        CryptoStream cs = new CryptoStream(fsCrypt,
            RMCrypto.CreateDecryptor(key, key),
            CryptoStreamMode.Read);

        FileStream fsOut = new FileStream(outputFile, FileMode.Create);

        int data;
        while ((data = cs.ReadByte()) != -1)
            fsOut.WriteByte((byte)data);

        fsOut.Close();
        cs.Close();
        fsCrypt.Close();

    }
}

来源：http://www.codeproject.com/Articles/26085/File-Encryption-and-Decryption-in-C

回复于 2024-04-20T23:01:44+08:00

一个有机体的大小是另一个有点娇小，虽然我们看到它时都知道很贵 . 眨眼眨眼 .

尝试在您的环境中对以下内容进行基准测试，并查看您所处的位置：

编辑2012年2月13日：代码已经更新，因为我已经悄悄进入了错误.Mea culpa .

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

...

    // Rfc2898DeriveBytes constants:
    public readonly byte[] salt = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; // Must be at least eight bytes.  MAKE THIS SALTIER!
    public const int iterations = 1042; // Recommendation is >= 1000.

    /// <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 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.CreateNew, 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 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.CreateNew, 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);
                }
            }
        }
    }

回复于 2024-04-20T23:01:44+08:00

10

通常，当数据在一台计算机（如服务器）上加密，然后由另一台计算机（客户端）解密时，使用您所描述的策略 . 服务器将使用对称密钥加密（用于性能）使用新生成的密钥加密数据，并使用公钥（匹配客户端的私钥）加密此对称密钥 . 服务器向客户端发送加密数据和加密对称密钥 . 客户端可以用它的私钥解密对称密钥，然后使用这个对称密钥来解密数据 . 如果您正在加密和解密同一台计算机上的数据，则使用RSA和AES可能没有意义，因为您不会尝试将加密密钥传递给另一台计算机 .

回复于 2024-04-20T23:01:44+08:00
12

就像你所听到的那样，非对称加密技术（如RSA）比对称加密技术（例如AES）慢得多，但它的优点是（简单的密钥管理，例如保护的单个私钥） .

密钥（双关语）是利用两者的优点（非对称私钥和对称速度）而忽略了另一方的不便（许多密钥和慢速） .

您可以通过每个文件使用一次RSA（没有巨大的性能影响）来加密用于加密（更快）大文件的（对称）密钥 . 这种对称密钥的包装允许您只管理一个私钥 .

这是一个链接到我的旧（但仍然是真的）blog post，它提供了一个使用C＃和.NET框架（Microsoft Mono）的例子 .

回复于 2024-04-20T23:01:44+08:00

加密/解密大文件（.NET）

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