ADAM, Active Directory, LDAP, ADFS, Identity

Question

What is the difference/relation between ADAM, Active Directory, LDAP, ADFS, Windows Identity, cardspace and which server (Windows 2003, Windows 2008) uses what?

Answer 1

Active Directory is a server component for administrating windows domains and storing related informations like details about users. It provides implementations of the network protocols LDAP, DNS, CIFS and Kerberos. It's part of Windows Server 2003 as well as Windows Server 2008 with some modifications in the latter case.

ADAM was somewhat like the little brother of Active Directory. It only contained an implementation of LDAP. With Windows Server 2008 it was renamed to LDS, Lightweight Directory Services. ADAM/LDS can also be installed on non-server versions of Windows.

LDAP is a protocol for administrating the data of a directory service. Data within a directory services are stored in a hierarchical manner, a tree. Entries within that tree can contain a set of attributes where each has a name and a value. They are mostly used for storing user related informations like usernames, passwords, email addresses and so on, as there are standardized schemas for this purpose and it's widely supported by applications.

ADFS is a technology which enables Single Sign-On for users of web applications within an Identity Federation. In a very short form: Imagine two organizations which have their user data stored within an active directory. Now each organization wants to give the users of the other organization access to its web applications, but with the restriction that the user data itself should neither be copied nor be fully accessible to the other organization. Thats the kind of problem ADFS can solve. May require an hour of reading & researching before fully understood.

Answer 2

Just to fill in the gaps above:

ADFS is an example of a STS (Security Token Service). STS's can be configured to have a trust relationship with each other. Imagine you have a company which only has internal users and they want to expand to external users. That means that all external users have to register, get a user name, password etc. Perhaps the company doesn't want to store all this stuff. They realise that most of their external users already have an OpenId account. So they federate (trust) their ADFS with an STS that accepts OpenId credentials.

When an external user wants to access the company website, they are asked what kind of user they are via a drop down. They select OpenID. They are then taken to the OpenId site where they authenticate. The user is then redirected back to the company ADFS with a signed token which states that OpenId has authenticated the user. Since there is a trust relationship, the ADFS accepts the authentication and allows the user access to the web site.

None of the OpenId credentials are stored by the company.

Effectively, you have outsourced authentication.

ADFS currently runs on Windows Server 2008 R2.

For Windows Identity (in the context of ADFS) I assume you are asking about Windows Identity Foundation (WIF). This is essentially a set of .NET classes that are added to a project using VS that makes the application "claims aware". There is a VS tool called FedUtil that maps an application to a STS and describes the claims that will be provided. (A claim is an attribute e.g. name, DOB etc.) When a user accesses the application, WIF redirects the user to the mapped STS where the user logs in. WIF then provides the application with a set of claims. Based on these, the application can alter flows based on the user claims. E.g. only users with a claim type of Role with a value of Editor can alter pages.

WIF can also act as an Access Manager E.g. only Editors can access this page. Other users simply receive an error.

In WIF, an application is referred to as a "Relying Party" (RP).

WIF inside VS requires Vista or Windows 7.

Since STS's can be federated with each other, each STS can provide a group of claims.

E.g. in the example above, the OpenId STS can provide the user's name while the company ADFS can provide information not pertinent to OpenId e.g role in the company.

Cardspace is a mechanism to authenticate via a digital identity e.g. an enabled application can ask you to login by selecting one of your "cards", one of which might be e.g. your personal X509 certificate. The application would then check this against the credentials it has stored.

In February 2011, Microsoft announced that they would no longer be developing the Windows CardSpace product.