Re: [jose] The role of JWK

[Sergey Beryozkin <[e-mail]>]

Hi Justin -
I can only afford sometimes looking at how others do something I'm not 
clear about but eventually would hack things my own way :-)

Can you please give me a favor and address a couple of questions I asked 
in the previous message too ?

Cheers, Sergey
On 14/08/14 18:14, Justin Richer wrote:
> Sergey - it's an Apache licensed project. Copy away! (with attribution) :)
>
>   -- Justin
>
> On 08/14/2014 12:42 PM, Sergey Beryozkin wrote:
>> Hi Richard and Justin
>>
>> Very helpful, many thanks !
>>
>> Richard: thanks for the link, the idea of using JWK as a standard
>> medium for shipping the key (information) is something that helps to
>> understand why JWK is referred to so much in the specifications like
>> JWE/JWS
>>
>> Justin: I'll try my best not to copy the Java code you linked too :-).
>>
>> Thanks for links to the examples, let me ask few questions below:
>>
>> On 14/08/14 16:04, Justin Richer wrote:
>>> Services are starting to publish their public keys as JWK instead of
>>> X509, since a JWK doesn't require a trusted CA and can be much more
>>> easily rotated at runtime.
>> Sorry if it is off-topic, is JWK representing a public key (the public
>> exponent) is effectively a self-signed public key/cert ? What provides
>> the extra trust into such JWK ? I've heard here about JWK Thumbprints ?
>>
>>> This is the class from our OAuth/OpenID
>>> Connect system that builds signers and validators off of a public-key
>>> JWK (using the Nimbus-DS JOSE library):
>>>
>>> https://github.com/mitreid-connect/OpenID-Connect-Java-Spring-Server/blob/master/openid-connect-common/src/main/java/org/mitre/jwt/signer/service/impl/JWKSetCacheService.java
>>>
>>>
>>>
>>> To add to that, with the private/shared key components of JWK, it can be
>>> a very effective key store. Our OAuth server uses this for its keys,
>>> this is the class that reads the file and makes the keys available as
>>> Java key objects to the rest of the system:
>>>
>>> https://github.com/mitreid-connect/OpenID-Connect-Java-Spring-Server/blob/master/openid-connect-common/src/main/java/org/mitre/jose/keystore/JWKSetKeyStore.java
>>>
>>>
>>> As you can see, these are both exceedingly simple classes because they
>>> simple read the URL (in the first case) or file (in the second case) and
>>> parse the JSON found there into a JWK set, which is then used to create
>>> the bare keys in the Java security framework. This is the RSA public key
>>> parser for example:
>>>
>>> https://bitbucket.org/connect2id/nimbus-jose-jwt/src/0d5b12b4d4b84c822bec4af368b3bea5120cb310/src/main/java/com/nimbusds/jose/jwk/RSAKey.java?at=master#cl-1395
>>>
>>>
>>>
>>> Finally, in order to make these keys more easy to deal with, we wrote a
>>> simple key generator program that will spin up a new RSA, EC, or Oct key
>>> and print it out as a JWK:
>>>
>>>     https://github.com/mitreid-connect/json-web-key-generator
>>>
>>>
>>> Whenever we deploy a new copy of our server somewhere, we also pull down
>>> this program and run it to generate a new JWK key set (with public and
>>> private keys) that we use to start up the server. The alternative, which
>>> we used to do, was to use OpenSSL to generate a self-signed X509
>>> certificate that we effectively threw away the trust chain for -- lots
>>> of extra effort to create information that we didn't want and then
>>> ignore it on the far end, all to get a simple keypair. It was
>>> unnecessarily complex from all ends, and the switch to JWK has been much
>>> nicer to deal with.
>>>
>> Is the simplicity of making a demo application running fast a major
>> factor of preferring JWK to self-signed X509  ? What about the
>> synchronization between the existing X509-based key storage and the
>> new JWK-aware storages ?
>>
>> Thanks, Sergey
>>
>>>   -- Justin
>>>
>>> On 08/14/2014 09:25 AM, Richard Barnes wrote:
>>>> 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
>>>> <[e-mail] <mailto:[e-mail]>> 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
>>>>
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