C# “C”；“坏数据”；解密加密文件时发生异常

嘿，老实说，我对加密和解密，甚至是c语言都很陌生。基本上，我有一个tcp聊天服务器，“保存”日志并加密文本文件。这是我加密的方式（基于MSDN示例）：

该方法成功地对文件进行了完全加密。这是我的解密方法：

public static void DecryptFile(string strInputFileName, string strOutputFileName, string strKey)
{
    DESCryptoServiceProvider des = new DESCryptoServiceProvider();
    des.Key = ASCIIEncoding.ASCII.GetBytes(strKey);
    des.IV = ASCIIEncoding.ASCII.GetBytes(strKey);

    byte[] te = new byte[1024];
    FileStream fsRead = new FileStream(strInputFileName, FileMode.Open, FileAccess.Read);
    ICryptoTransform desdecrypt = des.CreateDecryptor();          

    CryptoStream cryptostream = new CryptoStream(fsRead, desdecrypt, CryptoStreamMode.Read);
    StreamWriter fsDecrypted = new StreamWriter(strOutputFileName);            

    fsDecrypted.Write(new StreamReader(cryptostream).ReadToEnd());//This is where the "Bad Data" occurs.
    fsDecrypted.Flush();
    fsDecrypted.Close();
    fsRead.Close();
}

当我检查cryptostream对象时，它说它抛出了一个异常，“Stream不支持查找”

任何帮助都将不胜感激

这里：

    cryptostream.Write(byteArrayInput, 0, byteArrayInput.Length);
    fsIn.Close();
    fsOut.Close();

您正在直接关闭

fsOut

，而没有关闭

cryptostream

。这意味着加密流没有机会刷新任何最终块等

此外：

• 使用

  语句，而不是手动调用Close或Dispose

• 您当前正在调用

  Read

  一次，并假设它将读取所有数据-您没有检查返回值。（出于某种原因，您还删除了输入文件的最后一个字节……为什么？）通常，您应该循环，读取缓冲区，然后写出您读取的字节数，直到read方法返回0。如果您使用的是.NET4，

  Stream.CopyTo

  是您的朋友

为我工作，完整的代码是

 public static string DecryptString(string encriptedText, string key)
   {

       try
       {


           //Convert the text into bytest
           byte[] ecriptedBytes = System.Convert.FromBase64String(encriptedText);

           // Create a memory stream to the passed buffer
           MemoryStream objMemStream = new MemoryStream(ecriptedBytes);

           //Set the legal keys and initialization verctors
           objCrptoService.Key = GetLegalsecretKey(key);
           objCrptoService.IV = GetLegalIV();

           // Create a CryptoStream using the memory stream and the cryptographic service provider  version
           // of the Data Encryption stanadard algorithm key
           CryptoStream objCryptStream = new CryptoStream(objMemStream, objCrptoService.CreateDecryptor(), CryptoStreamMode.Read);

           // Create a StreamReader for reading the stream.
           //StreamReader objstreamReader = new StreamReader(objCryptStream);
           MemoryStream stream = new MemoryStream();
           objCryptStream.CopyTo(stream);
           stream.Position = 0;
           StreamReader R = new StreamReader(stream);
           string outputText = R.ReadToEnd();

           // Close the streams.
           R.Close();
           objCryptStream.Close();
           objMemStream.Close();

           return outputText;
       }
       catch (Exception exc)
       {
           return "";
       }
   }

---

解决我的问题的方法是在创建文件时调用cryptostream上的FlushFinalBlock

                CryptoStream cryptostream = new CryptoStream(memoryStream, this._encryptionKeyHelper.Encryptor(), CryptoStreamMode.Write);

            xmlser.Serialize(cryptostream, builderObject);

            cryptostream.FlushFinalBlock();

---

谢谢我真的需要进一步研究这个问题。我在试验MSDN中的代码示例，却不知道它们到底做了什么。我将FlushFinalBlock（）调用到cryptostream，并从输入文件中删除了-1，从而解决了这个问题。谢谢

 public static string DecryptString(string encriptedText, string key)
   {

       try
       {


           //Convert the text into bytest
           byte[] ecriptedBytes = System.Convert.FromBase64String(encriptedText);

           // Create a memory stream to the passed buffer
           MemoryStream objMemStream = new MemoryStream(ecriptedBytes);

           //Set the legal keys and initialization verctors
           objCrptoService.Key = GetLegalsecretKey(key);
           objCrptoService.IV = GetLegalIV();

           // Create a CryptoStream using the memory stream and the cryptographic service provider  version
           // of the Data Encryption stanadard algorithm key
           CryptoStream objCryptStream = new CryptoStream(objMemStream, objCrptoService.CreateDecryptor(), CryptoStreamMode.Read);

           // Create a StreamReader for reading the stream.
           //StreamReader objstreamReader = new StreamReader(objCryptStream);
           MemoryStream stream = new MemoryStream();
           objCryptStream.CopyTo(stream);
           stream.Position = 0;
           StreamReader R = new StreamReader(stream);
           string outputText = R.ReadToEnd();

           // Close the streams.
           R.Close();
           objCryptStream.Close();
           objMemStream.Close();

           return outputText;
       }
       catch (Exception exc)
       {
           return "";
       }
   }

                CryptoStream cryptostream = new CryptoStream(memoryStream, this._encryptionKeyHelper.Encryptor(), CryptoStreamMode.Write);

            xmlser.Serialize(cryptostream, builderObject);

            cryptostream.FlushFinalBlock();