c＃RijndaelManaged加密和解密有時會失敗

Question

編輯：解決 - 問題是解密函數。更正的解密函數可以在下面的答案中找到。

我花了最後一天的時間試圖找出我在這個AES實現中出錯的地方。我們需要能夠加密/解密大文件，因此我使用了文件流並將每個塊寫入磁盤。 AES是一個要求，因爲這需要與使用AES/CBC/PKCS5Padding（其中據我所知，相當於PKCS7/CBC）用Java編寫的現有系統工作

此實現適用於最文件。然而，有幾個文件丟失了原始數據的最後5個字節。該文件將解密沒有錯誤，但哈希不匹配，缺少的字節是真實數據和尾隨零的組合。

應該注意的是，這些流在加密之前和之後都是gzip（代碼在底部）。

加密

public static void AesEncrypt(byte[] keyBytes, byte[] ivBytes, Stream dataStream, FileStream outStream) 
    { 
     RijndaelManaged symmetricKey = new RijndaelManaged(); 
     symmetricKey.Mode = CipherMode.CBC; 
     symmetricKey.Padding = PaddingMode.PKCS7; 
     symmetricKey.BlockSize = 128; 
     symmetricKey.KeySize = 256; 

     const int chunkSize = 4096;//1024 * 1024 * 10; 

     using (ICryptoTransform encryptor = symmetricKey.CreateEncryptor(keyBytes, ivBytes)) 
     { 
      using (CryptoStream cryptoStream = new CryptoStream(outStream, encryptor, CryptoStreamMode.Write)) 
      { 
       while (dataStream.Position != dataStream.Length) 
       { 
        long remainingBytes = dataStream.Length - dataStream.Position; 
        var buffer = chunkSize > remainingBytes ? new byte[(int)remainingBytes] : new byte[chunkSize]; 

        dataStream.Read(buffer, 0, buffer.Length); 
        cryptoStream.Write(buffer, 0, buffer.Length); 
        cryptoStream.Flush(); 
       } 
       cryptoStream.FlushFinalBlock(); 
      } 
     } 
     symmetricKey.Clear(); 
    } 

解密

public static void AesDecrypt(byte[] keyBytes, byte[] ivBytes, Stream dataStream, FileStream outStream) 
    { 
     RijndaelManaged symmetricKey = new RijndaelManaged(); 
     symmetricKey.Mode = CipherMode.CBC; 
     symmetricKey.Padding = PaddingMode.PKCS7; 
     symmetricKey.BlockSize = 128; 
     symmetricKey.KeySize = keyBytes.Length == 32 ? 256 : 128; 

     const int chunkSize = 4096; 

     using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, ivBytes)) 
     { 
      using (CryptoStream cryptoStream = new CryptoStream(dataStream, decryptor, CryptoStreamMode.Read)) 
      { 
       while (dataStream.Position != dataStream.Length) 
       { 
        long remainingBytes = dataStream.Length - dataStream.Position; 
        var buffer = chunkSize > remainingBytes 
         ? new byte[(int) remainingBytes] 
         : new byte[chunkSize]; 

        cryptoStream.Read(buffer, 0, buffer.Length); 
        outStream.Write(buffer, 0, buffer.Length); 
        outStream.Flush(); 
       } 
       //cryptoStream.FlushFinalBlock(); // Was throwing an exception 
      } 
     } 
     symmetricKey.Clear(); 
    } 

壓縮（在此之前加密）

public static void StreamCompress(Stream dataStream, FileStream outStream) 
    { 
     dataStream.Position = 0; 
     outStream.Position = 0; 

     const int chunkSize = 4096; 
     using (GZipStream gzs = new GZipStream(outStream, CompressionMode.Compress)) 
     { 
      while (dataStream.Position != dataStream.Length) 
      { 
       long remainingBytes = dataStream.Length - dataStream.Position; 
       var buffer = chunkSize > remainingBytes ? new byte[(int)remainingBytes] : new byte[chunkSize]; 
       dataStream.Read(buffer, 0, buffer.Length); 
       gzs.Write(buffer, 0, buffer.Length); 
       gzs.Flush(); 
      } 
     } 
    } 

減壓（解密後）

public static void StreamDecompress(Stream dataStream, FileStream outStream) 
    { 
     byte[] buffer = new byte[4096]; 
     dataStream.Position = 0; 
     using (GZipStream gzs = new GZipStream(dataStream, CompressionMode.Decompress)) 
     { 
      for (int r = -1; r != 0; r = gzs.Read(buffer, 0, buffer.Length)) 
       if (r > 0) outStream.Write(buffer, 0, r); 
     } 
} 

我已經通過一些其他的問題，走了，但想不通爲什麼這個只發生在一些文件。失敗的文件大小是46,854,144字節。這似乎很好地處理較大和較小的文件。

任何幫助將不勝感激。

Answer 1

問題出在我解密數據的方式。我錯誤地使用了CryptoStream。如果任何人有興趣，更新的解密功能如下。

public static void AesDecrypt(byte[] keyBytes, byte[] ivBytes, Stream dataStream, FileStream outStream) 
    { 
     dataStream.Position = 0; 
     outStream.Position = 0; 

     RijndaelManaged symmetricKey = new RijndaelManaged(); 
     symmetricKey.Mode = CipherMode.CBC; 
     symmetricKey.Padding = PaddingMode.PKCS7; 
     symmetricKey.BlockSize = 128; 
     symmetricKey.KeySize = keyBytes.Length == 32 ? 256 : 128; 

     const int chunkSize = 4096; 

     using (ICryptoTransform decryptor = symmetricKey.CreateDecryptor(keyBytes, ivBytes)) 
     { 
      using (CryptoStream cryptoStream = new CryptoStream(outStream, decryptor, CryptoStreamMode.Write)) 
      { 

       while (dataStream.Position != dataStream.Length) 
       { 
        long remainingBytes = dataStream.Length - dataStream.Position; 
        var buffer = chunkSize > remainingBytes 
         ? new byte[(int) remainingBytes] 
         : new byte[chunkSize]; 

        var bytesRead = dataStream.Read(buffer, 0, buffer.Length); 
        cryptoStream.Write(buffer, 0, bytesRead); 
       } 
       cryptoStream.FlushFinalBlock(); 
      } 
     } 
     symmetricKey.Clear(); 
    }