CryptoStream 可以让基本流保持打开状态吗?

Can a CryptoStream leave the base Stream open?(CryptoStream 可以让基本流保持打开状态吗?)

问题描述

我创建了一个 MemoryStream，将它传递给 CryptoStream 进行写入.我希望 CryptoStream 进行加密，并让 MemoryStream 保持打开状态，然后再读入其他内容.但是一旦CryptoStream被处理，它也会处理MemoryStream.

I create a MemoryStream, pass it to CryptoStream for writing. I want the CryptoStream to encrypt, and leave the MemoryStream open for me to then read into something else. But as soon as CryptoStream is disposed, it disposes of MemoryStream too.

CryptoStream 可以让基础 MemoryStream 以某种方式打开吗?

Can CryptoStream leave the base MemoryStream open somehow?

using (MemoryStream scratch = new MemoryStream())
{
    using (AesManaged aes = new AesManaged())
    {
        // <snip>
        // Set some aes parameters, including Key, IV, etc.
        // </snip>
        ICryptoTransform encryptor = aes.CreateEncryptor();
        using (CryptoStream myCryptoStream = new CryptoStream(scratch, encryptor, CryptoStreamMode.Write))
        {
            myCryptoStream.Write(someByteArray, 0, someByteArray.Length);
        }
    }
    // Here, I'm still within the MemoryStream block, so I expect
    // MemoryStream to still be usable.
    scratch.Position = 0;    // Throws ObjectDisposedException
    byte[] scratchBytes = new byte[scratch.Length];
    scratch.Read(scratchBytes,0,scratchBytes.Length);
    return Convert.ToBase64String(scratchBytes);
}

推荐答案

您可以使用 using 语句.您将需要手动管理对象的处置，您还需要调用 FlushFinialBlock() 以确保所有数据在处理之前都已写入底层流.

You can but you will not be able to use using statements. You will need to manually manage the disposing of the object and you will also need to call FlushFinialBlock() to make sure all the data was written out to the underlying stream before working on it.

一旦您完成了对流的所有工作，您就可以处理在最后的 finally 块中等待的所有资源.

Once all you are done working with the stream you can then dispose all of the resources you where waiting on in the finally block at the end.

MemoryStream scratch = null;
AesManaged aes = null;
CryptoStream myCryptoStream = null;
try
{
    scratch = new MemoryStream();
    aes = new AesManaged();

    // <snip>
    // Set some aes parameters, including Key, IV, etc.
    // </snip>
    ICryptoTransform encryptor = aes.CreateEncryptor();
    myCryptoStream = new CryptoStream(scratch, encryptor, CryptoStreamMode.Write);
    myCryptoStream.Write(someByteArray, 0, someByteArray.Length);

    //Flush the data out so it is fully written to the underlying stream.
    myCryptoStream.FlushFinalBlock();

    scratch.Position = 0; 
    byte[] scratchBytes = new byte[scratch.Length];
    scratch.Read(scratchBytes,0,scratchBytes.Length);
    return Convert.ToBase64String(scratchBytes);
}
finally
{
    //Dispose all of the disposeable objects we created in reverse order.

    if(myCryptoStream != null)
        myCryptoStream.Dispose();

    if(aes != null)
        aes.Dispose();

    if(scratch != null)
        scratch.Dispose();
}

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