Re: [W3C Web Crypto WG] PROPOSAL to close ISSUE-22 (Should CryptoOperations be clonable)

If ISSUE-22 is closed, then it becomes impossible to do correctly 
progressive hash/encryption with the WebCrypto API.

This might be destroyed right away but please see below a proposal, it 
is not really a clone but a continuation of the operation resuming from 
the previous state (which as a non crypto expert maybe I am simplifying 
too much), see the example at the end, at least that's an attempt...

This is based on the assumption than independently of which progress 
could be fired following some process invocations at the same time you 
call finish, you are only interested by the final result.


|interfaceCryptoOperation  : EventTarget {
   voidprocess  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-method-process>(ArrayBufferView buffer);
   voidfinish  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-method-finish>(boolean? resume);
   voidabort  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-method-abort>();

   readonly attributeKey  <http://www.w3.org/TR/WebCryptoAPI/#dfn-Key>?key  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-key>;
   readonly attributeAlgorithm  <http://www.w3.org/TR/WebCryptoAPI/#dfn-Algorithm>  algorithm  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-algorithm>;
   readonly attribute anyresult  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-result>;
||   readonly attribute any?resume  <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-result>;|
|   readonly attribute any? final;|
  


        12.4.2. The|finish(boolean? resume)|method

When|finish(boolean? resume)| 
<http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-method-finish>method 
is called, the user agent must run the steps below.

 1.

    If the internal state is in the|"error"|state, throw
    an|InvalidStateError|exception and abort these steps.

 2.

    Set the internal state to|"complete"|. If resume is true let copy be
    a copy of the list of pending data and set the resume attribute to
    result

 3.

    If the underlying cryptographic implementation for the
    specifiedalgorithm
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-algorithm>does
    not support multi-part cryptographic operations,
    asynchronouslyprocess data
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-process-data>,
    allowing the task that invoked this algorithm to continue.

 4.

    Once all items in thelist of pending data
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-list-of-pending-data>have
    beenprocessed
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-process-data>,if
    resume is true, restore the list of pending data with copy and set
    final to result, queue a task
    <http://www.w3.org/TR/WebCryptoAPI/#queue-a-task>tofire a simple
    event
    <http://www.w3.org/TR/WebCryptoAPI/#fire-a-simple-event>called|oncomplete|
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-oncomplete>at the|CryptoOperation|
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation>.


        12.4.1.|process(ArrayBufferView data)|

When the|process(ArrayBufferView data)|method is called, the user agent 
must run the following steps:

 1.

    If the internal state is in the|"error"|state, throw
    an|InvalidStateError|exception and abort these steps.

 2.

    Letdatabe the data to be processed.

 3.

    Adddatato thelist of pending data
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-list-of-pending-data>.

 4. If the resume attribute is not undefined, update result with resume
 5.

    If the underlying cryptographic implementation for the
    specifiedalgorithm
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-algorithm>supports
    multi-part cryptographic operations, asynchrouslyprocess data
    <http://www.w3.org/TR/WebCryptoAPI/#dfn-CryptoOperation-process-data>,
    allowing the task that invoked this algorithm to continue.

Example :

The algorithm processes 3 bytes :

process(ABCD) {result=abc, pending=D}
finish(true) {result=abcd,final=abcd,resume=abc,pending=D}
process(EFGH)
     step 4 {result=abc,final=abcd,resume=abc,pending=D}
     step 5 {result=abcdefg,final=abcd,resume=abc,pending=H}
finish(true) {result=abcdefgh,final=abcdefgh,resume=abcdefg,pending=H}

The reason to use final attribute is that process does modify result and 
then progress could fire before complete and then the result in complete 
would not be the good one.


Le 04/04/2013 11:46, GALINDO Virginie a écrit :
>
> Dear all,
>
> I suggest that we close the ISSUE-22 
> http://www.w3.org/2012/webcrypto/track/issues/22 , with the rationale 
> that the WG did not make any progress /contribution on cloning. As 
> such I interpret it as no interest or need to have that feature 
> covered by our Web Crypto API.
>
> This proposal will be submitted to the vote during our next call on 
> the 15^th of April.
>
> Regards,
>
> Virginie
>

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