逐行加密/解密文件？

Question

我相當新手加密，我試圖讓逐行加密工作;在應用程序運行期間，我需要能夠將加密行附加到文件中，而不僅僅是一個大型的大規模加密 - 一切 - 保存。儘管如此，我還是有一段野獸。這是我的加密，在我自己的幾次失敗的嘗試後，無恥被盜：

class Encryption 
    { 
     private static readonly byte[] SALT = new byte[] { 0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c }; 

     public static byte[] Encrypt(byte[] plain, string password) 
     { 
      MemoryStream memoryStream; 
      CryptoStream cryptoStream; 
      Rijndael rijndael = Rijndael.Create(); 
      Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(password, SALT); 
      rijndael.Key = pdb.GetBytes(32); 
      rijndael.IV = pdb.GetBytes(16); 
      memoryStream = new MemoryStream(); 
      cryptoStream = new CryptoStream(memoryStream, rijndael.CreateEncryptor(), CryptoStreamMode.Write); 
      cryptoStream.Write(plain, 0, plain.Length); 
      cryptoStream.FlushFinalBlock(); 
      cryptoStream.Close(); 
      return memoryStream.ToArray(); 
     } 

     public static byte[] Decrypt(byte[] cipher, string password) 
     { 
      MemoryStream memoryStream; 
      CryptoStream cryptoStream; 
      Rijndael rijndael = Rijndael.Create(); 
      Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(password, SALT); 
      rijndael.Key = pdb.GetBytes(32); 
      rijndael.IV = pdb.GetBytes(16); 
      memoryStream = new MemoryStream(); 
      cryptoStream = new CryptoStream(memoryStream, rijndael.CreateDecryptor(), CryptoStreamMode.Write); 
      cryptoStream.Write(cipher, 0, cipher.Length); 
      cryptoStream.FlushFinalBlock(); 
      cryptoStream.Close(); 
      return memoryStream.ToArray(); 
     } 
    } 

，這裏是一個虛擬函數展示如何我嘗試它：

 

     private void EncryptFile(string filepath, string outputPath, string password) 
     { 
      FileInfo fileInfo = new FileInfo(filepath); 
      string filename = fileInfo.Name; 

      string fullpath = outputPath + "\\" + filename; 

      BinaryWriter writer = new BinaryWriter(File.OpenWrite(fullpath), Encoding.ASCII); 

      /// Two methods that I've attempted here: 
      /// 1. The desired method: encrypt line by line - I assumed I'd be able to generate 
      ///  multiple blocks of data and decrypt them later. This isn't working 

      //string[] lines = File.ReadAllLines(filepath); 

      /// 2. Just read the whole thing and encrypt and write it in one swoop. 

      string line = File.ReadAllText(filepath); 

      //foreach(string line in lines) 
      { 
       byte[] bytes = Encoding.ASCII.GetBytes(line); 
       byte[] encoded = Encryption.Encrypt(bytes, password); 

       writer.Write(encoded); 
       writer.Flush(); 
      } 

      writer.Close(); 
     } 



     private void DecryptFile(string filepath, string outputPath, string password) 
     { 
      FileInfo fileInfo = new FileInfo(filepath); 
      string filename = fileInfo.Name; 
      string fullpath = outputPath + "\\" + filename; 

      StreamWriter writer = new StreamWriter(fullpath, false, Encoding.UTF8); 

      byte[] bytes = File.ReadAllBytes(filepath); 

      /// Here is the method that's working at the moment for decrypting; just 
      /// grab all the data and decrypt it on one swoop. 

      byte[] decrypted = Encryption.Decrypt(bytes, password); 

      string s = Encoding.ASCII.GetString(decrypted); 

      writer.Write(s); 
      writer.Flush(); 


      /// I've tried a number of things here to decrypt line by line, 
      /// none of which work. This crashes with an issue about the padding 
      /// being invalid. 

      /* 
      int index = 0; 
      int count = 32; 

      while (index

我不完全知道我應該再來一次。我一直徘徊在揣測事物和在線閱讀示例，但他們似乎都是如何加密整個文件，或者只是加密一段數據，除了立即解密它之外別無它物。我應該如何處理逐行寫作？

Answer 1

不是爲你編程，而是給你一個你可以實現的方案。

如果你有每行加密，我想你也希望能夠解密每行。請注意，「行」對於計算機來說是一個相當不方便的術語。這只是一堆以某種行結束符結尾的字符。字符本身使用特定的character-encoding進行編碼。

此外，我會做出以下假設：

• 加密文本應線被呈現，這意味着該字節需要從二進制轉換爲字符（使用encoding）;
• 您希望使用單個密鑰，同時保持安全;
• 您不需要完整性保護或密文驗證，只需保密。

現在的想法很簡單：

1. 創建使用基於密碼的密鑰導出函數一個鍵;
2. 打開文本文件進行閱讀（使用正確的character-encoding）;
3. 讀取一行並將該行再次轉換爲字節（例如，使用UTF-8）;
4. 創建一個輸出流，在下面創建一個字節數組;
5. 創建一個隨機IV並將其寫入字節數組（IV總是單個塊大小）;
6. 創建加密流並將其連接到相同的輸出流;
7. 加密編碼後的行;
8. base 64對加密字節進行編碼，並確保它保留在一行中;
9. 將編碼的加密行寫入新的文本文件。

爲了做相反的事，雖然應該從base 64解碼後的字節中檢索IV，並且當然應該使用與在加密期間使用的相同方法來計算密鑰。