Question

How to authenticate users without the burden of setting up and securely maintaining a user database?

Context

Management of the user identities is often a burdensome task and in SaaS applications it often consumes a lot of time if done right.

Solution

Reusing existing user sign-in and sign-on features developed and maintained by third parties is an effective way to outsource authentication tasks to a third party. While the technical solutions employed by the third parties are often state-of-the-art, such outsourcing bears inevitable risks of privacy protection of the users, especially when the federated entities are social networks.