Encryption-less SP to auth against encryption-mandating IdP?

[Curry, Warren]

Some  non technical aspects added to this.

Encryption and signing are /should not be optional.    IT is the right thing to do in all cases.

Vendors or campus developers should be "strongly encouraged"  to the point of extreme exception .  Support the encryption and signing you are trying to avoid.

We have a very few exceptions.   But it is difficult for any SP in our base to be approved to not encrypt the assertion , etc.

This is not technical but  rather standard, practice and risk based practice that we live by.   I know many others who are essentially very similar.       Vendors will and have aligned when pushed on or other vendors exist.  Institutionally developed applications are simply expected to accommodate the standard practice of requiring SP to encrypt /sign etc..  .

Of 2000+ SPs running at our institution, we can count on my fingers SPs with exceptions and some of those are startup exceptions while adjustments/fixes are made to the service provider to align with the institutional practice and standard of encryption... .

-whc

Warren Curry
Identity Architect
UF Information Technology - Indentity Services
720 SW 2nd Street - Ayers Bldg
352-273-1383
http://identity.it.ufl.edu/

From: users <users-bounces at shibboleth.net> On Behalf Of Domingues, Michael D
Sent: Thursday, January 24, 2019 11:53 AM
To: users at shibboleth.net
Subject: Re: Encryption-less SP to auth against encryption-mandating IdP?


Hi Daniel,



What portions of the proposed system are under your control? Are you responsible for the web application that wants to receive user data (the service provider), the system that authenticate your users (the identity provider), or both?



Fundamentally, Shibboleth isn't just one product --- it's a suite of products developed to fulfill the two (primary) roles in a SAML login flow. One piece of software, the Shibboleth Service Provider (SP) works as an authentication middleware in conjunction with your web server, through something like mod_shib. mod_shib isn't the SP, it just bridges the SP software to your web application. The Shibboleth SP handles the generation of AuthN requests, comes with metadata (that you'll need to customize), and parses the SAML assertions that get sent to it, exposing identity data to your web application via server variables (or headers).



The other primary piece of software Shibboleth Identity Provider. It handles responding to AuthN requests, authenticating your users, then resolving identity data from underlying data connectors (LDAP, SQL, your person registry, etc) and sending SAML assertions to the SPs that sent the AuthN request in the first place.



Typically, you're only concerned with one of these things --- you're an application developer (or server admin) looking to get the Service Provider installed, or an identity team, looking to maintain the Identity Provider infrastructure for your institution.



If you control the SP, you absolutely can support encryption, metadata generation, etc. If you control the IdP, you can configure it on a per-SP basis (see the documentation for relying-party.xml [1]) to change its requirements depending on what an SP supports. In this scenario, if you control the IdP but not the SP, you could configure the IdP to permit non-signed AuthN requests, and send unencrypted assertions to the SP in question.



I hope this helps,



Michael



[1] https://wiki.shibboleth.net/confluence/display/IDP30/RelyingPartyConfiguration<https://urldefense.proofpoint.com/v2/url?u=https-3A__wiki.shibboleth.net_confluence_display_IDP30_RelyingPartyConfiguration&d=DwMFAg&c=pZJPUDQ3SB9JplYbifm4nt2lEVG5pWx2KikqINpWlZM&r=UBkKx63rTinSBj-2DQ-E7g&m=RDSS14TKNDX7wgCXGQtKRRZINvo0NxkDusbs5Lb-3pY&s=PI2_MXR_TqSIVvQT7KT2Fq2Wsljd_-hcUKyNTnZMFSw&e=>

________________________________
From: users <users-bounces at shibboleth.net<mailto:users-bounces at shibboleth.net>> on behalf of Daniel Smith <danielesmith at gmail.com<mailto:danielesmith at gmail.com>>
Sent: Thursday, January 24, 2019 10:40:42 AM
To: users at shibboleth.net<mailto:users at shibboleth.net>
Subject: Encryption-less SP to auth against encryption-mandating IdP?

I'm new to Shibboleth as of today, and the documentation is a little overwhelming. I was wondering if the following scenario is possible:

1. SP requires SAML 2.0 assertion for user groups to assign roles, but does not support assertion decryption, nor metadata generation, nor authn request signing
2. IdP mandates assertion encryption and authn request signing
3. Shibboleth hopefully sits in the middle, sending signed authn requests to IdP and decrypted SAML assertions to SP

Ideally I'd like to use mod_shib as the SP already has Apache running. Is there a walkthrough for this kind of scenario or do I just have to keep reading? Or, is this kind of encryption-one-way-but-not-the-other not supported?

Thanks,
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