W3C home > Mailing lists > Public > public-webcrypto@w3.org > March 2014

Re: JWK import/export as ECMAScript objects, rather than ArrayBuffer

From: Richard Barnes <rlb@ipv.sx>
Date: Fri, 28 Mar 2014 00:49:12 -0400
Message-ID: <CAL02cgRJT82Re1fS2LXccec5UKcrQNQFcE1CnzF0-g4fmHpfxA@mail.gmail.com>
To: Ryan Sleevi <sleevi@google.com>
Cc: "public-webcrypto@w3.org" <public-webcrypto@w3.org>
On Fri, Mar 28, 2014 at 12:47 AM, Ryan Sleevi <sleevi@google.com> wrote:

>
> On Mar 27, 2014 9:45 PM, "Richard Barnes" <rlb@ipv.sx> wrote:
> >
> > One minor note here:
> >
> >
> > On Tue, Mar 11, 2014 at 8:22 PM, Ryan Sleevi <sleevi@google.com> wrote:
> >>
> >> The motivation:
> >>
> >> * Provide a means of easy interchange with Web Sockets (eg: by allowing
> Text Frame, rather than imposing Binary Frame, as done by send(ArrayBuffer)
> )
> >> * Provide a means of easy interchange of JWK with postMessage (eg: by
> not requiring a Key object itself be posted)
> >> * Provide a means of easy integration with larger JSON-backed messages
> >>
> >> That is, presume a structure
> >> {
> >>   'larger_message': 'something',
> >>   'jwk': [{
> >>     'kid': 'foo',
> >>     'alg': 'RSA',
> >>     'kty': 'RSA1_5',
> >>     'n': '....',
> >>     'e': '....'
> >>   }]
> >> }
> >>
> >> Under the current API, one has two options - depending on UA support
> for http://encoding.spec.whatwg.org/#api
> >>
> >> With Encoding support:
> >>
> >> // Makes 3 additional copies of message.jwk
> >> // 1 for the .stringify
> >> // 1 for the TextEncoder
> >> // 1 for the importKey (cloning the ArrayBuffer)
> >> // By definition, this copies *all* fields of message.jwk, including
> those not used by importKey (eg: 'kid')
> >>
> >> message = JSON.parse(message);
> >> jwkBuf = (new TextEncoder("utf-8")).encode(JSON.stringify(message.jwk));
> >> window.crypto.subtle.importKey("jwk", jwkBuf, { name:
> "RSAES-PKCS1-v1_5" }, [ "encrypt", "decrypt"] );
> >>
> >> Without Encoding support:
> >> It's necessary to do something like strToUTF8Arr (
> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding)
> >>
> >> Under the proposed API, one simply does
> >>
> >> // Makes 1 additional copy of message.jwk
> >> // 1 for the importKey (cloning message.jwk)
> >> // By definition, this *does not* copy all fields of message.jwk - only
> those fields used for the import (eg: 'kid' is NOT copied)
> >> window.crypto.subtle.importKey("jwk", message.jwk, { name:
> "RSAES-PKCS1-v1_5" }, [ "encrypt", "decrypt" ]);
> >>
> >>
> >> Types used:
> >>
> >> dictionary JwkKeyDictionary {
> >>   DOMString kty;
> >>   DOMString alg;
> >>   boolean ext;
> >>   DOMString[] usages;
> >> };
> >>
> >> dictionary JwkEcKeyDictionary : JwkKeyDictionary {
> >>   DOMString crv;
> >>   DOMString x;
> >>   DOMString y;
> >>   DOMString d;
> >> };
> >>
> >> dictionary JwkRsaOtherPrimeDictionary {
> >>   DOMString r;
> >>   DOMString d;
> >>   DOMString t;
> >> };
> >>
> >> dictionary JwkRsaKeyDictionary : JwkKeyDictionary {
> >>   DOMString n;
> >>   DOMString e;
> >>   DOMString d;
> >>   DOMString p;
> >>   DOMString dp;
> >>   DOMString dq;
> >>   DOMString qi;
> >>   JwkRsaOtherPrimeDictionary[] oth;
> >> };
> >>
> >
> > This is missing the format for symmetric keys:
> >
> > dictionary JwkSymKeyDictionary : JwkKeyDictionary {
> >   DOMString k;
> > };
> >
> > This would be signaled by "kty" == "oct". I haven't reviewed the
> algorithms below to see if there need to be changes to accommodate this
> case.
> >
> > --Richard
> >
> >
>
> Yes, Mark pointed that out in the first reply :)
>
Guess that's why you guys are the editors :)

--Richard




> >>
> >>
> >> Changes to signatures:
> >> Old:
> >> Promise<any> importKey(KeyFormat format, CryptoOperationData keyData,
> AlgorithmIdentifier? algorithm, boolean extractable, KeyUsage[] keyUsages);
> >> Promise<any> exportKey(KeyFormat format, Key key);
> >>
> >> New:
> >> Promise<any> importKey(KeyFormat format, (CryptoOperationData or
> JwkRsaKeyDictionary or JwkEcKeyDictionary), AlgorithmIdentifier algorithm,
> boolean extractable, KeyUsage[] keyUsages);
> >> Promise<any> exportKey(KeyFormat format, Key key);
> >>
> >>
> >> Changes to algorithms:
> >> Wrap Key ( 14.3.1 /
> https://dvcs.w3.org/hg/webcrypto-api/raw-file/3f7df730b2c7/spec/Overview.html#SubtleCrypto-method-wrapKey)
> >>
> >> 12.
> >> * If format is "spki":
> >>   - Let bytes be the result of performing the export key operation
> specified the algorithm attribute of key using key and format.
> >> * If format is "pkcs8"
> >>   - Let bytes be the result of performing the export key operation
> specified the algorithm attribute of key using key and format.
> >> * If format is "jwk"
> >>   - Let object be the result of performing the export key operation
> specified by the algorithm attribute of key using key and format.
> >>   - Let stringifiedJwk be the result of invoking the JSON.stringify
> method specified in Section 15.12.3 of [ECMA-252], with /object/ as /value/.
> >>   - Let bytes be the UTF-8 encoding of stringifiedJwk
> >>
> >>
> >> From the algorithm-specific import key sections eg: using
> https://dvcs.w3.org/hg/webcrypto-api/raw-file/3f7df730b2c7/spec/Overview.html#rsassa-pkcs1-operationsas an example
> >>
> >> 4. If format is "jwk"
> >>   1. If /keyData/ is not an instance of a JwkRsaKeyDictionary, return
> an error ...
> >>   2. Let /jwk/ be /keyData/
> >>
> >> From the algorithm-specific export key sections - eg: using again
> RSASSA-PKCS1
> >>
> >> 4. If format is "jwk"
> >>   * Let /jwk/ be a new ECMAScript object created as if by the
> expression ({})
> >>   * _Set the property "n" of /jwk/_ to the _base64url-encoded_ modulus
> of the RSA public key represented by /key/, as specified by Section 6.3.1
> of [JWA]
> >>   * _Set the property "e" of /jwk/_ to the _base64url-encoded_ big
> integer exponent representation of the RSA public key represented by /key/,
> as specified by Section 6.3.1 of [JWA]
> >>   ...
> >>   * Let /result/ be /jwk/
> >>
> >> Terminology:
> >> When this specification says Set the property /name/ of /object/ to
> /value/, call the [[DefineOwnProperty]] internal method of /object/ with
> property name /name/, the Property Descriptor { [[Writable]]: true,
> [[Enumerable]]: true, [[Configurable]]: true, [[Value]]: /value/ }, and the
> Boolean flag false.
> >>
> >>
> >>
> >
> >
>
Received on Friday, 28 March 2014 04:49:40 UTC

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