Re: Thoughts behind the Streams API ED

On Thu, Nov 7, 2013 at 6:05 PM, Aymeric Vitte <vitteaymeric@gmail.com>wrote:

>  stop/resume:
>
> Indeed as I mentioned this is related to WebCrypto Issue22 but I don't
> think this is a unique case. Issue22 was closed because of lack of
> proposals to solve it, apparently I was the only one to care about it (but
> I saw recently some other messages that seem to be related), and finally
> this would involve a public clone method with associated security concerns.
>
> But with Streams it could be different, the application will internally
> clone the state of the operation probably eliminating the security issues,
> as simple as that.
>
> To describe simply the use case, let's take a progressive hash computing 4
> bytes by 4 bytes:
>
> incoming stream: ABCDE bytes
> hash operation: process ABCD, keep E for the next computation
> incoming stream: FGHI bytes + STOP-EOF
> hash operation: process EFGH, process STOP-EOF: clone the state of the
> hash, close the operation: digest hash with I
>

So, here, partial hash for ABCDEFGH is output


>
> resume:
> incoming stream: JKLF
> hash operation (clone): process IJKL, keep F for next computation
> etc...
>
>
and if we close the stream here we'll get a hash for ABCDEFGHIJKLFPPP (P is
padding). Right?


>  So you do not restart the operation as if it was the first time it was
> receiving data, you just continue it from the state it was when stop was
> received.
>
> That's not so unusual to do this, it has been requested many times in node.
>