Federating Azure AD with thinktecture Identity Server – Notes

First of all my apologies for not doing a good job here. I always planned to contribute this to the excellent identity server  but I never got enough bandwidth to do so. I’m constantly receiving request to share the details here so I decided to share notes/steps required to enable this and hopefully someone from community would do the bits I have long promised.

Here are steps…

1. Create a basic STS or tweak & use the lovely thinktecture IdentityServer v2 (my recommendation)
2. Within identity server, add a Relying Party Trust to ‘urn:federation:MicrosoftOnline’ which is the unique identifier used by of Azure AD for federation.
3. Establish a trust relationship between identity server and Azure AD using the Set-MsolDomainAuthentication cmdlet. This is how my trust relationship look like:

4. The IssuerUri MUST match the issuer URI of SAML assertion.

 

5. The protocol MSUT be WS-Federation for browser-based SSO

6. Following claims MUST be included in the issued tokens

• http://schemas.microsoft.com/LiveID/Federation/2008/05/ImmutableID
• http://schemas.xmlsoap.org/claims/UPN

7. The UPN must also be set as a name identifier.

Identity server code change # 1

---

var nameid = new Claim(ClaimTypes.NameIdentifier, “7960192”);
nameid.Properties[ClaimProperties.SamlNameIdentifierFormat] = “urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified”;
var outputClaims = new List<Claim> {

new Claim(“http://schemas.microsoft.com/LiveID/Federation/2008/05/ImmutableID”,”7960192″),
new Claim(“http://schemas.xmlsoap.org/claims/UPN”, “zulfiqar@bccoss.com”),
nameid
};

 

---

 

 

8. The signing algorithm MUST be SHA-1. Signing certificate can be a self-signed SSL certificate.

Identity server code change # 2

---

scope.SigningCredentials = new X509SigningCredentials(signingCert, SecurityAlgorithms.RsaSha1Signature, SecurityAlgorithms.Sha1Digest);

---

 

9. The token MUST be sent to: https://login.microsoftonline.com/login.srf

Looking forward to see this in identity server soon…

Federating Office 365 (Azure Active Directory) with a Custom STS

Let’s start of with a clarification: As of today, federating Office 365 (Azure AD) with a Custom STS is NOT supported by Microsoft.  Today the only supported STSs are AD FS 2.0, Shibboleth 2, Optimal IDM Federation Services and PingFederate 6.10.

With that cleared, Office 365 STS supports both WS-Federation & SAML protocols for user authentication which means technically any compatible STS can be used as the Identity Provider STS for Office 365 services or other Relying Parties with a trust relationship with Azure Active Directory.

Azure AD supports In-cloud & Federated Identities.

With In-Cloud identities all user information, including the passwords, are stored in the online directory.

With Federating identities, only basic information is stored in online directory (as shadow accounts) and user identities are mastered in on-premise directories. Passwords are never copied to online directory and Azure AD relies on federation for user sign in.

A key prerequisite for Office 365 SSO is to create federated identities (shadow accounts) in Azure AD and there are different options/tools to do this.

1. DirSync is the recommended tool but it only supports Active Directory as the identity source. DirSync & AD FS 2.0 are the primary tools to enable federation between an on-premises AD and Azure AD.
2. Graph API is a new RESTful API to manage online directory and looks very promising for creating cloud-only identities. Graph API today doesn’t support creating Federated identities.
3. MSOL PowerShell cmdlets: These cmdlets use the SOAP based Provisioning Service and are functionally quite rich. They support most of the operations including the creation of federated identities. I have used these cmdlet for my scenairo. Few commerical tools also wrap these cmdlets to perform various Office 365 provisioning operations.
4. Forfront Identity Manager (FIM) is another potential option which can create Federated accounts from source directories other than AD but I haven’t explored that in detail.

Now once you have the federated identities provisioned (or synced from your on-premises user identity store) in Azure AD, the next step is to establish a trust relationship between Azure AD and your custom STS. This is assuming you have already done the domain verification etc.

I have used Set-MsolDomainAuthentication cmdlet for this.

Set-MsolDomainAuthentication –DomainName bccoss.com –federationBrandName bccoss.com -Authentication Federated  -PassiveLogOnUri $url -SigningCertificate $certData -IssuerUri $uri -ActiveLogOnUri $ecpUrl -LogOffUri $logoutUrl -PreferredAuthenticationProtocol WSFed

 

At this stage, if I browse to the Microsoft Online Services portal (http://portal.microsoftonline.com/) and choose to login using my federated domain (@bccoss.com) – I got redirected to my custom STS.

In this case, I’m using Thinktecture STS but that doesn’t work out of box with Office 365 / Azure AD so I have to modify the STS to make it compatible with Azure AD. I’ll explain the Office 365 compatibility requirements of an STS in a future post.

I’ll also try to contribute my Thinktecture modification to code back to git at some point.