[mdx] Joe on 3.1.1

[Cantor, Scott]

On 9/26/13 10:03 AM, "Ian Young" <ian at iay.org.uk> wrote:

>>   As a wanna-be crypto guy, I also have some concern about
>>   a newish spec specifying deprecated hashes (e.g., MD5 should
>>   really not be re the required "lowest common denominator"
>>   required transform for this or any other purpose)
>
>Scott (and this was also my position):
>
>> We're not using the hashes for security here, so I doubt there's much
>> concern.

I actually had to retract that somewhat. We do have a use case where the
actual entityID being returned to us is not known ahead of time, but only
after the query. That's the SAML artifact case.

It's still a stretch to envision an attach on the hash that would result
in a problem since you'd have to, I guess, have a collision that resulted
in a different entityID's metadata coming back, but the artifact
resolution would just fail at that point. I don't know, it seems a
stretch, but hash analysis is not my area.

>If we were picking just one, of course, there's no rule that says that
>we'd have to pick either MD5 or SHA-1. If we thought that there was a
>potential security issue being surfaced, we could also just pick SHA-256.

It's actually because SAML artifacts that we need SHA-1. So if we're
looking for a single one, that would have to be it.

This not baked into SAML per se, but into the SAML 2.0 artifact format
everybody uses.

-- Scott