"要解密的数据长度无效." Rijndael解密期间的异常

Question

我得到"要解密的数据长度无效".我试图解密内存流时的异常.我是初学者,无法弄清楚什么是错的.怎么了？

public bool EncryptStream()
    {

        string password = @"myKey123"; // Your Key Here
        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        s_EncryptedStream = new MemoryStream();
        int NoOfBytes;
        byte[] b_Buffer = new byte[8192];

        s_MemoryStream.Seek(0, SeekOrigin.Begin);

        RijndaelManaged RMCrypto = new RijndaelManaged();

        s_CrytpoStream = new CryptoStream(s_EncryptedStream,
            RMCrypto.CreateEncryptor(key, key),
            CryptoStreamMode.Write);

        while (s_MemoryStream.Length < s_MemoryStream.Position)
        {
            NoOfBytes = s_MemoryStream.Read(b_Buffer, 0, 8192);
            s_CrytpoStream.Write(b_Buffer, 0, NoOfBytes);
        }

        s_MemoryStream.Seek(0, SeekOrigin.Begin);

        while (s_EncryptedStream.Position < s_EncryptedStream.Length)
        {
            NoOfBytes = s_EncryptedStream.Read(b_Buffer, 0, 8192);
            s_MemoryStream.Write(b_Buffer, 0, NoOfBytes);

        }
        s_CrytpoStream.Flush();
        s_CrytpoStream.Close();

        return true;

    }


    public bool DecryptStream()
    {


        string password = @"myKey123"; // Your Key Here

        UnicodeEncoding UE = new UnicodeEncoding();
        byte[] key = UE.GetBytes(password);

        int NoOfBytes;
        byte[] b_Buffer = new byte[8192];

        s_DecryptedStream = new MemoryStream();


        RijndaelManaged RMCrypto = new RijndaelManaged();

        s_CrytpoStream = new CryptoStream(s_MemoryStream,
            RMCrypto.CreateDecryptor(key, key),
            CryptoStreamMode.Read);

        s_MemoryStream.Seek(0, SeekOrigin.Begin);

        while (s_MemoryStream.Length > s_MemoryStream.Position)
        {
            NoOfBytes = s_CrytpoStream.Read(b_Buffer, 0, 8192);
            s_DecryptedStream.Write(b_Buffer, 0, NoOfBytes);
        }

        s_DecryptedStream.Seek(0, SeekOrigin.Begin);
        s_MemoryStream.Seek(0, SeekOrigin.Begin);

        while (s_DecryptedStream.Position < s_DecryptedStream.Length)
        {
            NoOfBytes = s_DecryptedStream.Read(b_Buffer, 0, 8192);
            s_MemoryStream.Write(b_Buffer, 0, NoOfBytes);

        }

        s_CrytpoStream.Flush();
        s_CrytpoStream.Close();

        return true;

    }

Answer 1

首先,这个while循环条件永远不对:

while (s_MemoryStream.Length < s_MemoryStream.Position)

这个位置如何超越长度？

复制流的常用模式不是使用流的长度,而是重复读取,直到返回的值不为正.正如你在这段代码中那样做了两次,你不妨将它封装起来:

public static void CopyStream(Stream input, Stream output)
{
    byte[] buffer = new byte[8192];
    int read;
    while ( (read = input.Read(buffer, 0, buffer.Length)) > 0)
    {
        output.Write(buffer, 0, read);
    }
}

最好使用using语句来清理字符串.此外,该Encoding.Unicode属性意味着您不必UnicodeEncoding自己创建新的.另外,我通常发现设置Position属性比使用更具可读性Seek.最后,如果一个值总是存在,那么返回一个值就没有意义了true.所以,你的代码将成为:

public void EncryptStream()
{
    string password = @"myKey123"; // Your Key Here
    byte[] key = Encoding.Unicode.GetBytes(password);

    s_EncryptedStream = new MemoryStream();
    s_MemoryStream.Position = 0;

    RijndaelManaged RMCrypto = new RijndaelManaged();

    using (Stream crytpoStream = new CryptoStream(s_EncryptedStream,
        RMCrypto.CreateEncryptor(key, key),
        CryptoStreamMode.Write))
    {
        CopyStream(s_MemoryStream, cryptoStream);
    }

    s_MemoryStream.Position = 0;
    s_EncryptedStream.Position = 0;
    CopyStream(s_EncryptedStream, s_MemoryStream);
}

public void DecryptStream()
{
    string password = @"myKey123"; // Your Key Here
    byte[] key = Encoding.Unicode.GetBytes(password);

    s_DecryptedStream = new MemoryStream();
    s_MemoryStream.Position = 0;

    RijndaelManaged RMCrypto = new RijndaelManaged();

    using (Stream crytpoStream = new CryptoStream(s_MemoryStream,
        RMCrypto.CreateDecryptor(key, key),
        CryptoStreamMode.Read))
    {
        CopyStream(cryptoStream, s_DecryptedStream);
    }

    s_DecryptedStream.Position = 0;
    s_MemoryStream.Position = 0;

    CopyStream(s_DecryptedStream, s_MemoryStream);
}

即使在修改了这段代码之后,感觉就像你在这里有太多的非局部变量.我不明白为什么所有的这应该是实例变量.使流加密或解密为参数(连同密码)并返回带有加密/解密数据的内存流,或仅返回字节数组.