解密加密文件时出现C＃“Bad Data”exception
嘿，我对加密和解密很新，甚至是c＃语言，说实话。 基本上，我有一个tcp聊天服务器，可以“保存”日志并加密文本文件。 这是我加密的方式（基于MSDN示例）：
public static void EncryptFile(string strInputFileName, string strOutputFileName, string strKey) { FileStream fsIn = new FileStream(strInputFileName, FileMode.Open, FileAccess.Read); FileStream fsOut = new FileStream(strOutputFileName, FileMode.Create, FileAccess.Write); DESCryptoServiceProvider des = new DESCryptoServiceProvider(); des.Key = ASCIIEncoding.ASCII.GetBytes(strKey); des.IV = ASCIIEncoding.ASCII.GetBytes(strKey); ICryptoTransform desencrypt = des.CreateEncryptor(); CryptoStream cryptostream = new CryptoStream(fsOut, desencrypt, CryptoStreamMode.Write); byte[] byteArrayInput = new byte[fsIn.Length - 1]; fsIn.Read(byteArrayInput, 0, byteArrayInput.Length); cryptostream.Write(byteArrayInput, 0, byteArrayInput.Length); fsIn.Close(); fsOut.Close(); } 方法成功完全加密文件。 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exception，“Stream不支持搜索”。
任何帮助将不胜感激！
这里：
cryptostream.Write(byteArrayInput, 0, byteArrayInput.Length); fsIn.Close(); fsOut.Close();
您正在关闭fsOut ，而不关闭cryptostream 。 这意味着加密流没有机会刷新任何最终块等。
另外：
- 使用
using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 – 您不会检查返回值。 （你也是出于某种原因删除了输入文件的最后一个字节……为什么？）通常，你应该循环，读入缓冲区然后写出你读取的多少字节，直到Read方法返回0如果你使用的是.NET 4，Stream.CopyTo就是你的朋友。
objCryptStream.CopyTo(stream);
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 ""; } }
修复我的问题是在cryptostream上调用FlushFinalBlock，创建文件时
CryptoStream cryptostream = new CryptoStream(memoryStream, this._encryptionKeyHelper.Encryptor(), CryptoStreamMode.Write); xmlser.Serialize(cryptostream, builderObject); cryptostream.FlushFinalBlock();