This one's short but important - there's been a change in SharePoint 2013 when you install a custom claims provider. The IsUsedByDefault property is now set to False by default; in SharePoint 2010 it was True, which means as soon as you installed your custom claims provider everything "just worked". You will now have to go and change this, either after the fact or as part of your claims provider receiver assembly, in order to have your claims provider start working.
Also, I'm finding that those same tools used in SharePoint 2010 - the SharePoint Claims project with the HttpModule and web part that lists your claims, the ClaimsProviderActivation tool, that enables and disables a provider - are still quite handy in SharePoint 2013. As a quick plug to help you get started I'm attaching a ZIP file to this post with rebuilt versions of those tools that work with SharePoint 2013.
Custom Claim providers is a very important stuff and has to be addressed in proper way...........
Very good content.
Thank you for the heads-up and particularly for sharing the updated tool with us, found it really handy!
Steve, love your blog. Hey I have a dilemma. I have a need to support external non-windows users through SAML authentication. I have successfully setup ADFS with claims transformation logic to map the users to an internal "shadow" AD account. I am using SharePoint 2013. All is working with the exception of the BI stack. Specifically the BISM in a shared data source library connecting to Analysis Services (Tabular). Evidently, someone chose to not allow the issuance of Windows tokens from the c2wts even though the claim is from an internal domain, albeit via ADFS. Any thoughts on how to deliver a solution?