ADFS : SAML redirect to application via relayState and loginToRp

This post follows on from:

IDP Initiated Sign-on to SAML SP using SAML IDP

Prior reading:

• AD FS 2.0 RelayState 
• Supporting Identity Provider Initiated RelayState 

The question is around having a SAML IDP (Salesforce), ADFS as the RP-STS and multiple SAML RP.

Users may authenticate with either AD (via ADFS) or via Salesforce.

The easy way is to use RP Initiated but that wasn't an option.

In the link above, there is a useful tool to generate the relayState.

There are three text boxes:

IDP
RP-STS
Application

The article is somewhat confusing because the third text box refers both to a string to be passed to the application and the ADFS identifier of the application.

However, the use case we want i.e.

Identity provider security token server (STS) -> relying party STS (configured as a SAML-P endpoint) -> SAML relying party App

is supported.

I tried this with two ADFS - both v3.0.

So ADFS IDP = adfs-idp
ADFS RP-STS = adfs-rp-sts
Application ID = appid

which leads to:

https://adfs-idp/adfs/ls/idpinitiatedsignon.aspx
https://adfs-rp-sts/adfs/ls/
appid

and the URL is:

https://adfs-idp/adfs/ls/idpinitiatedsignon.aspx?RelayState=RPID%3Dhttps%253A%252F%252Fadfs-rp-sts%252Fadfs%252Fls%252F%26RelayState%3Dappid

So the user should authenticate on adfs-idp, be redirected to adfs-rp-sts, be already authenticated and then be redirected to the application.

However, I could not get this to work. I kept getting:

MSIS7001: The passive protocol context was not found or not valid. If the context was stored in cookies, the cookies that were presented by the client were not valid. Ensure that the client browser is configured to accept cookies from this website and retry this request.

If I left the third text box empty and removed the empty "RelayState=", I get:

https://adfs-idp/adfs/ls/idpinitiatedsignon.aspx?RelayState=RPID%3Dhttps%253A%252F%252Fadfs-rp-sts%252Fadfs%252Fls%252F

So the user should authenticate on adfs-idp, be redirected to adfs-rp-sts, be already authenticated and then select the application from the dropdown, This works.

For AD authentication, we can use the form at the top of the article i.e. using the loginToRp parameter.

This gives:

https://adfs-rp-sts/adfs/ls/idpinitiatedsignon.aspx?loginToRp=appid

So the user should authenticate on adfs-rp-sts and be redirected to the application, This works.

Or we can take a completely different approach (albeit with ADFS 3.0) as per:

ADFS 3.0: Playing with Authentication

where you can use:

Set-AdfsRelyingPartyTrust

where you can configure any of your relying parties to use specific claims provider(s).

Note:

Just to call out @RobM's summary from the forum question above:

"If you have a SAML IDP and a WS-Federation SP, you can use a URL constructed in the following manner to sign in:

https://corporate.adfs.com/adfs/ls/?wa=wsignin1.0&whr=https://identity.provider.com/&wtrealm=https://service.provider.com

If you have a SAML IDP and a SAML SP, the URL looks like so:

https://identity.provider.com/idploginpath/login?RelayState=RPID%3Dhttps%253A%252F%252Fidentity.provider.com

Note that with WS-federation, the flow is ADFS --> IDP --> ADFS --> RP

With SAML only, the flow is IDP --> ADFS --> RP"

Enjoy!