加密例外：输入不是一个完整的块

Question

这是一个代码段I有用于设定masterpassword：

private void button1_Click(object sender, EventArgs e) 
    { 
     string current = textBox1.Text; 
     string newPass = textBox2.Text; 
     string confirmed = textBox3.Text; 
     string massPass = "winxp.pma"; 


     if (File.Exists(massPass)) 
     { 
      byte[] cipertext = File.ReadAllBytes(massPass); 
      string decoded; 
      if(Encryptor.TryDecrypt(current, cipertext, out decoded)) 
      { 
       FileStream fs = new FileStream(massPass, FileMode.Truncate, FileAccess.Write); 
       StreamWriter sw = new StreamWriter(fs, Encoding.UTF8); 
       if(newPass == confirmed) 
       { 
        byte[] newCipher = Encryptor.Encrypt(newPass, newPass); 
        string writeIt = System.Text.Encoding.UTF8.GetString(newCipher); 
        sw.Write(writeIt); 
        sw.Flush(); 
        sw.Close(); 
        fs.Close(); 
        this.Close(); 

       } 
       else 
       { 
        MessageBox.Show("New password do not match.", "Error", MessageBoxButtons.OK); 
       } 

      } 

     } 
     else 
     { 
      FileStream fs = new FileStream(massPass, FileMode.Create, FileAccess.Write); 
      StreamWriter sw = new StreamWriter(fs, Encoding.UTF8); 
      if (newPass == confirmed) 
      { 
       byte[] ciphertext = Encryptor.Encrypt(newPass, newPass); 
       string writeIt = System.Text.Encoding.UTF8.GetString(ciphertext); 
       sw.Write(ciphertext); 
       sw.Flush(); 
       sw.Close(); 
       fs.Close(); 
       this.Close(); 
      } 

回到主窗体上，我使用以下列方式的TryDecrypt方法：

private void S_Click(object sender, EventArgs e) 
    { 
     byte[] ciphertext = File.ReadAllBytes(massPass); 
     string decoded; 

      if (Encryptor.TryDecrypt(textBox1.Text, ciphertext, out decoded)) 
      { 
       accountGroupsBox.Enabled = true; 
       addNewPasswordToolStripMenuItem.Enabled = true; 
       label2.Text = "Interface Unlocked"; 

      } 
      else 
      { 
       MessageBox.Show("Incorrect Master Password.", "Authentication Error", MessageBoxButtons.OK); 
      } 

然而，正如我提到的，它不会返回true ....我打赌它是与我办理其他形式的文件流的方式，但我不明白什么不够发生在引擎盖下，以确定我是否正确地做。

Answer 1

您的输入流不完整。为了能够尝试解密它，它必须是一定的大小。确保你的加密过程是正确的。加密数据应该等于或长于您的普通数据。

我在其他网站上的结论是CryptoStream没有机会在输出文件关闭之前完成写入数据。在处理CryptoStream之前，输出流应保持打开状态，以便能够写入密文的其余部分和必要的填充。

我的测试代码：

public static byte[] Encrypt(string password, string plaintext, SymmetricAlgorithm algorithm) 
{ 
    byte[] key, iv; 
    CreateKeyIV(password, out key, out iv); 
    using (MemoryStream encrypted = new MemoryStream()) 
    { 
     using (CryptoStream enc = new CryptoStream(encrypted, algorithm.CreateEncryptor(key, iv), CryptoStreamMode.Write)) 
     using (StreamWriter writer = new StreamWriter(enc)) 
      writer.Write(plaintext); 
     return encrypted.ToArray(); 
    } 
}