Where is Microsoft.Identitymodel.Claims.dll ?

If you are trying to develop something with Claims (getting LDAP attributes in a ADFS environment) in SharePoint 2013 you will probably require to add a reference to Microsoft.IdentityModel.dll ; This should be available in Add Reference but most of the time is missing.

Your solutions are:

1. Do not use Identity Model 🙂
2. Install the Windows Identity Foundation
   1. For Windows 7, Windows Server 2003 Service Pack 2, Windows Server 2008 R2, Windows Server 2008 Service Pack 2, Windows Vista: Windows Identity Foundation and Windows Identity Foundation SDK;
   2. For Windows 8, Windows 10: Control Panel > All Control Panel Items > Programs and Features > Turn Windows feature on or off the feature is Windows Identity Foundation 3.5
   3. For Windows Server 2012; Windows Server 2012 R2; Windows Server 2016:  Server manager > Manage > Add Roles and Features > Features > Windows Identity Foundation 3.5
3. Add reference via NuGet Console (NuGet Package): Install-Package Microsoft.IdentityModel -Version 6.1.7600.16394