Mark Diodati sums up the recent SPML threads here. But one questions that needs to be answered, if not SPML then what? One alternative that has been put forward by Mark Diodati, Mark Wilcox, and others is the LDAP (or DSML) pull model of provisioning.
This model is to expose your user accounts via LDAP using a Virtual Directory (VD) instance exposed to your service provider. The service provider would periodically make calls to the VD to look for account CRUD operations.
There are several compelling advantages to this model;
- LDAP is already a standard protocol
- There are defacto standard schemas (the most common of which is the standard AD account)
- This is really just an extension of a model that has already been embraced in the enterprise (look at how many apps can be AD enabled)
Could that be it? Is the solution to service provider provisioning really this simple? No, at least not without SAML. While this model shows promise there is a problem; passwords. If your enterprise is not ready to use SAML to authenticate to your service provider, then you are left with two choices; both unpleasant.
First you could just punt on passwords and force your users to manage their passwords on their own. This is no worse than the situation without any provisioning, but certainly not where you could be if you used a provisioning solution to push the passwords out to the service provider as needed.
The second is to expose your password hashes via your VD. If your service provider supports the same salting and hashing algorithms, then the passwords could be synchronized by copying the hash across. In fact the recent version of the Google apps dir sync utility claims to be able to do just that.
But think about this for a moment. If you do that then the service provider knows the clear text password to log into your network for every one of your users that actually uses the service. After all, the user has to provide the clear text password to the service provider’s login page to generate the hash value to compare to the hash you sent them. If that’s the same as the hash value in AD, then the service provider knows your AD password by definition.
Do you trust Google with the clear text AD passwords? I’m not picking on Google; there simply aren’t any service providers I would trust with that information.
Another alternative I have heard is that the service provider’s login page would make an LDAP bind call back to the VD with the supplied password to do the authentication. Again, that gives the service provider a clear text version of your AD password.
Are you sure you really want to do that?
But if your enterprise and your service provider can implement SAML, then the LDAP pull model looks a lot more compelling. I would be curious to hear from anyone that has implemented this or is thinking of implementing it. And if anyone is using the password hash sync approach, I would be interested in hearing about as well.