经过多年的工作，AesManaged开始产生空字符串加密结果 [英] AesManaged started to produce null string encryption result after years of working perfectly

问题描述

几年前，我写了一个简单的包装器，基于 MSDN - AesManaged Class 代码，以掩盖在注册表中保存的值（只是为了防止手动篡改这些，没有更多）：

  public static string Encrypt（string s，byte [] key，byte [] iv）
 {
 byte [] enc; 
 
使用（AesManaged aes = new AesManaged（））
 {
 ICryptoTransform ict = aes.CreateEncryptor（key，iv）; 
 
使用（MemoryStream ms = new MemoryStream（））
使用（CryptoStream cs = new CryptoStream（ms，ict，CryptoStreamMode.Write））
使用（StreamWriter sw = new StreamWriter （cs））
 {
 sw.Write（s）; enc = ms.ToArray（）; 
} 
} 
 return Convert.ToBase64String（enc）; 
} 
 
 public static string Decrypt（string p，byte [] key，byte [] iv）
 {
 string s = null; 
 
使用（AesManaged aes = new AesManaged（））
 {
 ICryptoTransform ict = aes.CreateDecryptor（key，iv）; 
 
使用（MemoryStream ms = new MemoryStream（Convert.FromBase64String（p）））
使用（CryptoStream cs = new CryptoStream（ms，ict，CryptoStreamMode.Read））
使用（StreamReader sr = new StreamReader（cs））
 {
s = sr.ReadToEnd（）; 
} 
} 
 return s; 
} 
  

这些方法在这段时间内完美运行..直到昨天，当Encrypt生成null结果在一个有效的字符串。更改键和 iv 没有任何区别。尝试在几台机器上执行 - 相同的结果。没有例外被抛出。但是，解密仍然正常！

为什么 Encrypt（）突然失败？有没有一些Windows Update更改了播放栏？

解决方案

在找到并研究了几个类似的问题后（​​解密器提供空字符串; 在.NET中使用AES加密 - CryptographicException说填充无效，无法删除; 填充无效，无法删除，使用AesManaged ; 填充无效，无法删除使用AesManagedC＃解密字符串时的异常），并再次查看我的代码，我注意到与MSDN示例的区别。事实上，我做了一个优化和，就是那个打破了执行！代码必须以这种方式拼写：

  public static string Encrypt（string s，byte [] key，byte [] iv）
 {
 byte [] enc; 
 
使用（AesManaged aes = new AesManaged（））
 {
 ICryptoTransform ict = aes.CreateEncryptor（key，iv）; 
 
使用（MemoryStream ms = new MemoryStream（））
 {
 using（CryptoStream cs = new CryptoStream（ms，ict，CryptoStreamMode.Write））
 {
使用（StreamWriter sw = new StreamWriter（cs））
 {
 sw.Write（s）; 
} 
} 
 enc = ms.ToArray（）; 
} 
} 
 
 return Convert.ToBase64String（enc）; 
} 
  

请注意，每个使用（ ..）！是的，这意味着CryptoStream在我尝试使用缓冲区之前已经关闭了，因此被刷新了，使得这种方法安全。

不知道，为什么通过 @GregS 和 @HansPassant 没有这样做，但由于代码现在工作（恢复到原始版本:)，我的问题是关闭的。感谢上帝的版本控制！ ：））

谢谢各位指导我解决！

A few years ago I wrote a simple wrapper based on MSDN - AesManaged Class code, to obscure values saved in registry (simply to prevent manual tampering with these, nothing more):

public static string    Encrypt( string s, byte[] key, byte[] iv )
{
    byte[]  enc;

    using(  AesManaged aes =    new AesManaged( )  )
    {
        ICryptoTransform    ict =   aes.CreateEncryptor( key, iv );

        using(  MemoryStream ms= new MemoryStream( )  )
        using(  CryptoStream cs= new CryptoStream( ms, ict, CryptoStreamMode.Write )  )
        using(  StreamWriter sw= new StreamWriter( cs )  )
        {
            sw.Write( s );      enc =   ms.ToArray( );
        }
    }
    return  Convert.ToBase64String( enc );
}

public static string    Decrypt( string p, byte[] key, byte[] iv )
{
    string  s=  null;

    using(  AesManaged aes =    new AesManaged( )  )
    {
        ICryptoTransform    ict =   aes.CreateDecryptor( key, iv );

        using(  MemoryStream ms= new MemoryStream( Convert.FromBase64String( p ) )  )
        using(  CryptoStream cs= new CryptoStream( ms, ict, CryptoStreamMode.Read )  )
        using(  StreamReader sr= new StreamReader( cs )  )
        {
            s=  sr.ReadToEnd( );
        }
    }
    return  s;
}

These methods worked perfectly all this time .. until yesterday, when Encrypt produced a null result on a valid string. Changing key and iv does not make any difference. Tried executing on several machines - same result. No exceptions are thrown. However, decryption still works fine!

Why does Encrypt( ) suddenly fail? Is there some Windows Update that changed the play-field?

解决方案

After finding and studying several similar questions (Aes decryptor gives empty string; Using AES encryption in .NET - CryptographicException saying the padding is invalid and cannot be removed; "Padding is invalid and cannot be removed" using AesManaged; Padding is invalid and cannot be removed Exception while decrypting string using "AesManaged" C#) and looking at my code again, I noticed the difference with MSDN sample. Indeed, i made an optimization and that is, what broke the execution! The code must be spelled this way:

public static string    Encrypt( string s, byte[] key, byte[] iv )
{
    byte[]  enc;

    using(  AesManaged aes =    new AesManaged( )  )
    {
        ICryptoTransform    ict =   aes.CreateEncryptor( key, iv );

        using(  MemoryStream ms= new MemoryStream( )  )
        {
            using(  CryptoStream cs= new CryptoStream( ms, ict, CryptoStreamMode.Write ) )
            {
                using(  StreamWriter sw= new StreamWriter( cs )  )
                {
                    sw.Write( s );
                }
            }
            enc =   ms.ToArray( );
        }
    }

    return  Convert.ToBase64String( enc );
}

Notice the presence of curly braces after each using(..)! Yes, that means the CryptoStream is closed - and therefore flushed - before i attempt to use the buffer, making this approach safe.

No idea, why solution by @GregS and @HansPassant did not do it, but since the code works now (reverted to original version :), my issue is closed. Thank god for version control! :))

Thank you guys for guiding me to the solution!

这篇关于经过多年的工作，AesManaged开始产生空字符串加密结果的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！