WS-Security and GSS-API: How do I get the session key?

[Thomas Maslen]

On Feb 23, 2009, at 04:39, Speedo wrote:
> I guess this issue had been discussed before: WS-Security negotiates
> with Kerberos 5 but uses the session key in a different way from GSS
> tokens. Since GSS-API is the public API to access Kerberos 5, is there
> any recent progress in enhancing the GSS-API to provide a function
> like gss_get_session_key()?

Yes, we bumped up against this with our Java implementation of Kerberos,
GSSAPI, etc.

Since we have our own implementation (c.f. the ones that Sun and IBM ship
in their respective JDKs), I added a home-grown API[*] to extract the session
key from the GSSContext once the context is established, precisely to 
support the WS-Security Kerberos Token Profile.

But if that isn't an option...  the initial context token for the Kerberos 5
GSSAPI mechanism is essentially just an AP-REQ with a bit of GSSAPI
framing prepended, so perhaps you can strip off the GSSAPI cruft
(including the non-ASN.1 bytes), leaving you with the AP-REQ, and 
you probably have lots of tasty APIs to process that and then give you
the session key?




[*] I wish that the Java GSSAPI had an escape mechanism akin to
XMLReader.setProperty(String,Object) in SAX2