Re: Thoughts behind the Streams API ED

On Thu, Nov 7, 2013 at 6:27 PM, Aymeric Vitte <vitteaymeric@gmail.com>wrote:

>
> Le 07/11/2013 10:21, Takeshi Yoshino a écrit :
>
>  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
>
>
> No, you get the digest for ABCDEFGHI and you get a cloned operation which
> will restart from ABCDEFGH
>
>
>
OK.


>
>
>>
>> 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?
>
>
> If you close the stream here you get the digest for ABCDEFGHIJKLF
>
>
resume happens implicitly when new data comes in without explicit method
call say resume()?


>
>
>
>>  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.
>>
>
> --
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> node-Tor : https://www.github.com/Ayms/node-Tor
> GitHub : https://www.github.com/Ayms
>
>