"Pluggable" key serialization in JCE/JCA

[Michael StJohns]

On 3/25/2022 12:33 PM, Anders Rundgren wrote:
> On 2022-03-25 17:12, Anthony Scarpino wrote:
>> When you say "construct and EC key", do you mean creating an EC key from
>> an existing set of values via PKCS8 or X509 encoding?  Or are you
>> talking about EC key generation?
>
> I was talking about creating keys from parameter data supplied by for 
> example JOSE:
>   {
>     "kty": "EC",
>     "crv": "P-256",
>     "x": "6BKxpty8cI-exDzCkh-goU6dXq3MbcY0cd1LaAxiNrU",
>     "y": "mCbcvUzm44j3Lt2b5BPyQloQ91tf2D2V-gzeUxWaUdg"
>   }
>
> Apparently this particular issue have solution (as Michael StJohns 
> showed), although it is not particularity intuitive as well as 
> undocumented.
>
> Another take on this issue:
> https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/security/Key.html#getEncoded() 
>
> "Returns the key in its primary encoding format, or null if this key 
> does not support encoding"
>
> With COSE/JOSE there is no longer an obvious primary encoding format.

Of course there is.  You may not like that it's not COSE or JOSE, but 
the encoding spec remains as is and 10s of 1000s of implementations that 
use that encoding would be annoyed if you tried to claim a new "primary 
encoding format".

The SubjectPublicKeyInfo encoding for PublicKeys, the PKCS8 encoding for 
private keys, and RAW encoding for SecretKeys is what's there and I'm 
pretty sure won't change.  I occasionally wished for a getEncoded() 
method that took an encoding type as an argument (e.g. 
getEncoded("bareXY") or some such), but that's not in the API.

What I'd suggest is that you write a JEP for adding EncodedKeySpec 
classes for COSE and JOSE to the API.   I'd probably also add a 
GenericKeyEncodingSpec class.  That should be simple enough as a first step.

The second step would be to write and contribute a Jose and Cose 
KeyFactory implementation that uses those classes.

As I noted, it should be possible to externalize any preferred encoding 
by using the getKeySpec method of KeyFactory rather than just the key 
types default encoding.

Later, Mike


>
> Anders
>
>>
>> Tony