Get SP's URL from the attribute-Resolver.xml or atribute-filter.xml file

[Peter Schober]

* Glaidson Verzeletti <verzeletti at gmail.com> [2016-10-04 17:37]:
> I need to merge the URL of the SP (relay party) that is requesting
> authentication to the IdP with the user UID. From these two pieces of
> information, I will generate a hashMD5 that will serve as "username".
> 
> I deliver a 'username' unique for each SP that the user accesses.
> 
> This demand is part of a research project.

I'd strongly recommend not inventing new identifiers of that kind,
when existing ones are defined in the SAML standard that should
satisfy the same criteria.

Cf. 8.3.7 in SAML Core:
https://www.oasis-open.org/committees/download.php/56776/sstc-saml-core-errata-2.0-wd-07.pdf

The way the Shibboleth IDP implements this:
https://wiki.shibboleth.net/confluence/display/IDP30/PersistentNameIDGenerationConfiguration
this will produce an identifier that encodes an identifier for
subject, the SP's entityID and the IDP's entityID into a salted hash.
(Additionally that hash is accompanied by the recipient SP's and the
asserting IDP's entiyID in separate XML attributes. SP's are free to
use or ignore those additional data elements.)

If the research project insists on re-inventing the wheel (and
non-interoperably) there may be people who can help them get a bit of
clue. In that case feel free to provide specifics about the research
project (incl country/region of operation), possibly off-list.
-peter