Question

我需要在c＃中使用DES算法执行解密。我有加密图像的代码。我不知道代码要用图像标题执行解密。

以下是我的加密代码。

        FileStream fsInput = new FileStream(source, FileMode.Open, FileAccess.Read);

        FileStream fsEncrypted = new FileStream(destination, FileMode.Create, FileAccess.Write);
        DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
        DES.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
        DES.IV = ASCIIEncoding.ASCII.GetBytes(sKey);

        ICryptoTransform desencrypt = DES.CreateEncryptor();
        CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write);
        byte[] headerBuffer = new byte[54];
        fsInput.Read(headerBuffer, 0, headerBuffer.Length);
        var biCompression = BitConverter.ToInt32(headerBuffer, 30);

        if (biCompression != 0 && biCompression != 3)
        {
            throw new Exception("Compression is not in the correct format");
        }
        fsEncrypted.Write(headerBuffer, 0, headerBuffer.Length);
        fsInput.CopyTo(cryptostream);

        cryptostream.Close();
        fsInput.Close();
        fsEncrypted.Close();

Answer 1

您可以使用如下所示的Decrypt方法解密加密图像：

private static void Decrypt( string encryptedFilePath, string decryptedOutputLocation)
    {
        var key = "12345678";  //this will be the key you used for encryption

        FileStream fsInput = new FileStream(encryptedFilePath, FileMode.Open, FileAccess.Read);

        FileStream fsDecrypted = new FileStream(decryptedOutputLocation, FileMode.Create, FileAccess.Write);
        DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
        DES.Key = ASCIIEncoding.ASCII.GetBytes(key.ToCharArray());
        DES.IV = ASCIIEncoding.ASCII.GetBytes(key.ToCharArray());

        var desDecryptor = DES.CreateDecryptor();
        CryptoStream cryptostream = new CryptoStream(fsDecrypted, desDecryptor,
            CryptoStreamMode.Write);

        byte[] headerBuffer = new byte[54];

        fsInput.Read(headerBuffer, 0, headerBuffer.Length);

        fsDecrypted.Write(headerBuffer, 0, headerBuffer.Length);
        fsInput.CopyTo(cryptostream);

        cryptostream.Close();
        fsInput.Close();
        fsDecrypted.Close();
    }

BTW，在你的代码中

if (biCompression != 0 && biCompression != 3)
    {
        throw new Exception("Compression is not in the correct format");
    }

这将始终抛出异常。这也是你应该看的地方。

使用c＃.net中的DES算法解密图像

1 个答案: