c# - 加密和解密 MemoryStream

Question

我需要加密并稍后解密 MemoryStream(原始大型 PDF 文件)。我尝试了以下代码:

    public static string GenerateKey()
    {
        var desCrypto = (DESCryptoServiceProvider)DES.Create();

        return Encoding.ASCII.GetString(desCrypto.Key);
    }

    public static MemoryStream Encrypt(Stream fsInput,string sKey)
    {
        var fsEncrypted=new MemoryStream();

        var des = new DESCryptoServiceProvider
        {
            Key = Encoding.ASCII.GetBytes(sKey),
            IV = Encoding.ASCII.GetBytes(sKey)
        };
        var desencrypt = des.CreateEncryptor();
        var cryptostream = new CryptoStream(fsEncrypted,desencrypt,CryptoStreamMode.Write);

        var bytearrayinput = new byte[fsInput.Length];
        fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
        cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);
        fsInput.Close();

        fsEncrypted.Flush();
        fsEncrypted.Position = 0;
        return fsEncrypted;
    }

    public static MemoryStream Decrypt(Stream fsread,string sKey)
    {
        var des = new DESCryptoServiceProvider
        {
            Key = Encoding.ASCII.GetBytes(sKey),
            IV = Encoding.ASCII.GetBytes(sKey)
        };

        var sOutputFilename = new MemoryStream();
        var desdecrypt = des.CreateDecryptor();
        var cryptostreamDecr = new CryptoStream(fsread,desdecrypt,CryptoStreamMode.Read);

        var fsDecrypted = new StreamWriter(sOutputFilename);
        fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
        fsDecrypted.Flush();
        fsDecrypted.Close();
        sOutputFilename.Position = 0;

        return sOutputFilename;
    }

调用示例:

    var sSecretKey = FileHelper.GenerateKey();
    var encyptedPdfContent = FileHelper.Encrypt(httpPostedFile.InputStream, sSecretKey);

    var decryptedPdfContent = FileHelper.Decrypt(encyptedPdfContent, sSecretKey);

加密似乎按预期工作，但当我尝试解密时

fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());

返回给我 Bad Data 异常。

我的代码有什么问题？

我看了其他帖子，都是跟字符串编码(Encoding.Unicode)有关的。我没有字符串。我有一个根本没有编码的内存流!

Answer 1

请在解密方法中加入以下代码

des.Padding = PaddingMode.Zeros;