W3C home > Mailing lists > Public > public-webcrypto@w3.org > May 2013

Re: Web Crypto Spec Feedback on Dictionaries as return type properties

From: Ryan Sleevi <sleevi@google.com>
Date: Thu, 2 May 2013 13:52:54 -0700
Message-ID: <CACvaWvaLhxAFufSysNvOPuad0ohLmyHpud=DwhDv3m10jXqDDQ@mail.gmail.com>
To: Israel Hilerio <israelh@microsoft.com>
Cc: "public-webcrypto@w3.org" <public-webcrypto@w3.org>
I thought the more common alternative was to specify a parallel
interface that matches the Dictionary parameters, but with the values
set as readonly attributes.

On Thu, May 2, 2013 at 1:29 PM, Israel Hilerio <israelh@microsoft.com> wrote:
> While reviewing the latest editor's draft of the Web Crypto API [1], we noticed a potential problem that might we worth quickly addressing before the spec advances to last call.
>
> Web Crypto defines an "Algorithm" as a dictionary type [2]. The Algorithm dictionary is useful for specifying multiple input parameters to a variety of functions in a natural, JavaScript-friendly way.
>
> The Algorithm dictionaries are also available in CryptoOperation [3] and Key [4] to allow for inspection of the source algorithm information from which those objects were created.
>
> The potential problem we've found is that Algorithm is provided on CryptoOperation and Key as a readonly attribute. This syntactic form is strictly prohibited by WebIDL [5], which states:
>
> "The type of the attribute, after resolving typedefs, MUST NOT be a nullable or non-nullable version of any of the following types:
> .a sequence type
> .a dictionary
> .a union type that has a nullable or non-nullable sequence type or dictionary as one of its flattened member types" [6]
>
> Instead, the recommend technique for providing a dictionary type as output is via an operation, such as "getAlgorithm()". We'd like to recommend that we make a change now to convert the two occurrences that use Algorithm as an attribute in the spec to use a method instead. This will avoid a late-breaking API change later (at LC or CR) when other working groups review the spec and uncover this violation.  We're open to alternative name suggetions-"getAlgorithm" just seems like the least amount of churn to address the issue.
>
> This suggestion will have the following impact on the Key and CryptoOperation interfaces:
>
> interface CryptoOperation : EventTarget {
>   void init();
>   void processData(ArrayBufferView buffer);
>   void complete();
>   void abort();
>
>   readonly attribute Key? key;
>   readonly attribute any result;
>
>   Algorithm getAlgorithm();
>
>   [TreatNonCallableasNull] attribute Function? onabort;
>   [TreatNonCallableAsNull] attribute Function? onerror;
>   [TreatNonCallableAsNull] attribute Function? oninit;
>   [TreatNonCallableAsNull] attribute Function? onprogress;
>   [TreatNonCallableAsNull] attribute Function? oncomplete;
> };
>
> interface Key {
>   readonly attribute KeyType type;
>   readonly attribute bool extractable;
>   readonly attribute KeyUsage[] keyUsage;
>
>   Algorithm getAlgorithm();
> };
>
> Thanks,
> IE team
>
>
> [1] https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html
> [2] https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#algorithm-dictionary
> [3] https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#cryptooperation-interface
> [4] https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#key-interface
> [5] http://dev.w3.org/2006/webapi/WebIDL/
> [6] http://dev.w3.org/2006/webapi/WebIDL/#idl-attributes
>
>
>
Received on Thursday, 2 May 2013 20:53:21 UTC

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