[jose] The role of JWK

[Sergey Beryozkin <[e-mail]>]

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