Re: [jose] The role of JWK

Hey Sergey,

JWK isn't necessarily tied to JWE or JWS.  It can be used to represent the
public key that was used to encrypt a JWE (so that the recipient can look
up the private key), or the public key that should be used to verify a
JWS.  But it can also be used in other contexts.  For example, WebCrypto
uses JWK (among others) as a format for serializing keys.
https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#subtlecrypto-interface-datatypes

As that link suggests, JWK is effectively the same as the PKCS#8 format for
private keys and the SubjectPublicKeyInfo format for public keys -- just in
JSON instead of ASN.1.  It's a way to ship a key from one place to another,
for whatever reason you need to do that.

Hope that helps,
--Richard

On Thu, Aug 14, 2014 at 5:51 AM, Sergey Beryozkin <sberyozkin@gmail.com>
wrote:

> Hi,
>
> This is very likely a newbie question. What is the role of JWK ?
> According to [1] it is "... a (JSON) data structure that represents a
> cryptographic key".
>
> I can see plenty examples of JWK in the JWE specification. JWS and JWE
> headers can have a "jwk" property representing a given JWK.
>
> What confuses me is that the examples in JWE use JWK to describe the
> private parts of a given key. For example, when we talk about the RSA OAEP
> key encryption, JWK would show a private exponent of a given RSA key (JWE
> A1). Same for Aes Wrap secret key (JWE A3). Etc.
>
> So clearly one would not use a "jwk" JWE header to pass around a JWK
> representation of the key which was used to encrypt the content encryption
> key.
>
> So I'm thinking a JWK is:
> - a convenient way to describe a cryptographic key for JWE/JWS
> specifications to refer to it in the spec examples.
> - perhaps there's a long-term vision that the key stores would support JWK
> format directly ?
> - JWK is a 'container' for various key properties, some of those 'public'
> properties can be passed around as a JWE/JWS header;
>
> Am I on the right track, can someone please clarify it further ?
>
> Thanks, Sergey
>
>
> [1] http://tools.ietf.org/html/draft-ietf-jose-json-web-key-31#section-1
>
> _______________________________________________
> jose mailing list
> jose@ietf.org
> https://www.ietf.org/mailman/listinfo/jose
>