Shibboleth Developers

["Scott Cantor" <>]

> Interesting.  I hadn't thought of it as a documentation issue, but of 
> course a lot of these standards are vague enough as to their semantics 
> to leave lots of interpretations open... with the assumption that the 
> community of use will settle on a definition.

There are no rules whatsoever to follow. It's somewhat defined how to
represent keys, but not what they mean.

> The IdP code looks to me like it might do different things when 
> validating a signed SAML object vs. validating TLS.  In the former case, 
> I think the code just asks the Apache XMLSEC library to extract a public 
> key, and wandering through their code makes me think that it would 
> handle raw RSAKeyValue elements in there.  Insufficient documentation in 
> there to tell for sure without trying it.

Probably would work. Maybe even in C++.

> When validating TLS, I think the answer is no because the BasicTrust 
> code explicitly only looks at keys with X.509 certificates, and there is 
> an additional constraint that the certificate presented has to exactly 
> match the one in the metadata.  So I suppose in this sense the rest of 
> the certificate in the metadata is not actually ignored, its validity is 
> merely not checked.

C++ is the same. We debated the issue there since TLS always gives you a
full cert, but decided to compare certs, not keys.

> Apart from the extra size of a certificate vs. the raw key, I'd be 
> slightly interested in this from a "do what you say, say what you do" 
> point of view.  I've had a certain amount of push-back from people who 
> shall remain nameless but are deeply familiar with X.509;

Any use of X.509 is artifically imposed, and I am becoming convinced is
counterproductive, confusing, and pointless. Encryption will just hammer
that home for good, eliminating any possible key indirection for most
deployments. I think it will be to everybody's benefit, in the long run.

> their expectation is that if all that stuff is in there they'd expect the 
> certificate constraints to be honoured.

My view was that if you're bothering to force the insertion of a certificate
in the data, you've lost any expectation of being able to roll it over
independently, so evaluating it as a certificate is just creating more
chance for failure with no gain for deployment.

If you're going to indirect it, then really indirecting it provides whatever
value you might get.

-- Scott