＆QUOT;填充是无效的，不能删除＆QUOT;使用AesManaged [英] "Padding is invalid and cannot be removed" using AesManaged

问题描述

我试图让简单的加密/解密与AesManaged工作，但我一直试图关闭解密流时得到一个例外。这里的字符串被加密并正确解密，然后我得到的CryptographicException填充是无效的，不能被删除后Console.WriteLine打印正确的字符串。

任何想法？

 的MemoryStream毫秒​​=新的MemoryStream（）;
byte []的rawPlaintext = Encoding.Uni code.GetBytes（这是烦人！）;

使用（AES公司AES =新AesManaged（））
{
  aes.Padding = PaddingMode.PKCS7;
  aes.Key =新的字节[八分之一百二十八]
  aes.IV =新的字节[八分之一百二十八]

  使用（CryptoStream的CS =新的CryptoStream（MS，aes.CreateEncryptor（）
                                            CryptoStreamMode.Write））
  {
    cs.Write（rawPlaintext，0，rawPlaintext.Length）;
    cs.FlushFinalBlock（）;
  }

  MS =新的MemoryStream（ms.GetBuffer（））;
  使用（CryptoStream的CS =新的CryptoStream（MS，aes.CreateDecryptor（）
                                            CryptoStreamMode.Read））
  {
    byte []的RAWDATA =新的字节[rawPlaintext.Length]
    INT LEN = cs.Read（RAWDATA，0，rawPlaintext.Length）;
    字符串s = Encoding.Uni code.GetString（RAWDATA）;
    Console.WriteLine（多个）;
  }
}
 

解决方案

的技巧是使用 MemoryStream.ToArray（）。 我也改变了你的code，以便它使用了的CryptoStream 来写，在加密和解密。而你并不需要调用 CryptoStream.FlushFinalBlock（）明确，因为你必须在一个使用（）声明中，并刷新将发生在的Dispose（）。以下为我工作。

 字节[] rawPlaintext = System.Text.Encoding.Uni code.GetBytes（这一切清楚了吧！）;

使用（AES公司AES =新AesManaged（））
{
    aes.Padding = PaddingMode.PKCS7;
    aes.KeySize = 128; //位数
    aes.Key =新的字节[八分之一百二十八] // 16字节128位加密
    aes.IV =新的字节[八分之一百二十八] // AES需要16个字节的第四
    //应该设置密钥和IV在这里。好办法：从得到他们
    //通过Cryptography.Rfc2898DeriveBytes密码
    byte []的密文= NULL;
    byte []的明文= NULL;

    使用（MemoryStream的毫秒=新的MemoryStream（））
    {
        使用（CryptoStream的CS =新的CryptoStream（MS，aes.CreateEncryptor（），CryptoStreamMode.Write））
        {
            cs.Write（rawPlaintext，0，rawPlaintext.Length）;
        }

        密文= ms.ToArray（）;
    }


    使用（MemoryStream的毫秒=新的MemoryStream（））
    {
        使用（CryptoStream的CS =新的CryptoStream（MS，aes.CreateDecryptor（），CryptoStreamMode.Write））
        {
            cs.Write（密文，0，cipherText.Length）;
        }

        明文= ms.ToArray（）;
    }
    字符串s = System.Text.Encoding.Uni code.GetString（明文）;
    Console.WriteLine（多个）;
}
 

另外，我想你知道你将要明确设置<一个href="http://msdn.microsoft.com/en-us/library/system.security.cryptography.aesmanaged.mode.aspx">Mode在AesManaged实例，并使用<一个href="http://msdn.microsoft.com/en-us/library/system.security.cryptography.rfc2898derivebytes.aspx">System.Security.Cryptography.Rfc2898DeriveBytes导出密钥和IV从一个密码和盐

另见：
- <一个href="http://msdn.microsoft.com/en-us/library/system.security.cryptography.aesmanaged.aspx">AesManaged

I'm trying to get simple encryption/decryption working with AesManaged, but I keep getting an exception when trying to close the decryption stream. The string here gets encrypted and decrypted correctly, and then I get the CryptographicException "Padding was invalid and cannot be removed" after Console.WriteLine prints the correct string.

Any ideas?

MemoryStream ms = new MemoryStream();
byte[] rawPlaintext = Encoding.Unicode.GetBytes("This is annoying!");

using (Aes aes = new AesManaged())
{
  aes.Padding = PaddingMode.PKCS7;
  aes.Key = new byte[128/8];
  aes.IV = new byte[128/8];

  using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(),
                                            CryptoStreamMode.Write))
  {
    cs.Write(rawPlaintext, 0, rawPlaintext.Length);
    cs.FlushFinalBlock();
  }

  ms = new MemoryStream(ms.GetBuffer());
  using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(),
                                            CryptoStreamMode.Read))
  {
    byte[] rawData = new byte[rawPlaintext.Length];
    int len = cs.Read(rawData, 0, rawPlaintext.Length);
    string s = Encoding.Unicode.GetString(rawData);
    Console.WriteLine(s);
  }
}

解决方案

The trick is to use MemoryStream.ToArray(). I also changed your code so that it uses the CryptoStream to Write, in both encrypting and decrypting. And you don't need to call CryptoStream.FlushFinalBlock() explicitly, because you have it in a using() statement, and that flush will happen on Dispose(). The following works for me.

byte[] rawPlaintext = System.Text.Encoding.Unicode.GetBytes("This is all clear now!");

using (Aes aes = new AesManaged())
{
    aes.Padding = PaddingMode.PKCS7;
    aes.KeySize = 128;          // in bits
    aes.Key = new byte[128/8];  // 16 bytes for 128 bit encryption
    aes.IV = new byte[128/8];   // AES needs a 16-byte IV
    // Should set Key and IV here.  Good approach: derive them from 
    // a password via Cryptography.Rfc2898DeriveBytes 
    byte[] cipherText= null;
    byte[] plainText= null;

    using (MemoryStream ms = new MemoryStream())
    {
        using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
        {
            cs.Write(rawPlaintext, 0, rawPlaintext.Length);
        }

        cipherText= ms.ToArray();
    }


    using (MemoryStream ms = new MemoryStream())
    {
        using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
        {
            cs.Write(cipherText, 0, cipherText.Length);
        }

        plainText = ms.ToArray();
    }
    string s = System.Text.Encoding.Unicode.GetString(plainText);
    Console.WriteLine(s);
}

Also, I guess you know you will want to explicitly set the Mode of the AesManaged instance, and use System.Security.Cryptography.Rfc2898DeriveBytes to derive the Key and IV from a password and salt.

see also:
- AesManaged

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