One day Mickey was waiting for Minnie at the train station. Minnie came running to Mickey.
Minnie – Hey Mickey, why did you call me here, Is everything okay?
Mickey – Yes, I am going for an interview and one of the things I am expected to know is SSO, but I have no clue about it.
Minnie – Oh don’t worry. Let me explain it.
Mickey – But my train is approaching.
Minnie – That’s even great. Let me come with you and I will tell you a story on the train.
Mickey – Awesome
(Mickey and Minnie boarded the train)
Mickey – So shall we start
Minnie – Sure, to start with, SSO means Single Sign-On
Mickey – I know that.
Minnie – Have patience. Think of a lock and key. Every lock needs a key to open.
Mickey – That’s Right
Minnie – Think you have to enter a building that has many rooms. The building has a main door with a lock and each room as well, has its own door with a lock.
Mickey – It sounds scary !!!
Minnie – Shut up and listen.
Every door has a lock and there is a key to open the lock.
Now imagine you have to enter the building through the main door and then also go to multiple rooms. What will you do?
Mickey – Well, I will get the key for the main door and open it. Then I will do to each of the rooms and get the key and open them one by one.
Minnie – So will it be fun.
Mickey – Not exactly, going to each door and opening. It’s too much. It will be better if only the main door has a lock and once I get inside the main door, I should be allowed to the rooms inside without having to use a key again and again.
Minnie – Yes exactly that is what we call – SSO – Single Sign-On
Once you are authenticated at the main door, the rooms inside won’t ask you for authentication again and you can enter without using the key or the password for every room.
Mickey – So once the user unlocks the main door the other locks are unlocked as well. This is great and interesting…
Minnie – Yes, Now think of websites. Let’s say websites have locks. Not all but some do and to open the lock we need a key.
Mickey – I am getting it so far.
Minnie – So using this key you can enter into the website. And this key is the Id and password.
Mickey – I got it so far
Minnie – Now think of a huge system that can have multiple websites and applications each having a lock.
Now it may be very difficult if you have to unlock every page or application with a key.
Mickey – Hey, in my company there is the Intranet which has a lot of applications to be used by the employees
Minnie – Yes, think of a system like that. Now tell me do you have to provide a password on every website, webpage or application on the intranet.
Mickey – Not exactly. I just sign in to the intranet and then I can access everything.
Minnie – Exactly, because there is a central server and this is trusted by all the applications on your intranet. Once you login to this central server and are authenticated, you can then access all the applications.
This is because you have signed in to the central server and all the applications trust this server.
All these websites or applications may have there own server and infrastructure, but they honor the same Id and password used by the central server and therefore does not prompt to authenticate on every application/website
Mickey – I am getting this.
Minnie – Before going further, Let’s see a Wikipedia definition of SSO
“Single sign-on is an authentication scheme that allows a user to log in with a single ID and password to any of several related, yet independent, software systems.”
Mickey – I can now understand this.
Minnie – Okay, Now take an example of Google, Once you login to your Google account or Gmail, You can then access other Google apps like Photos, Sheets, Drive, Hangouts, YouTube, etc without having to log in again on each of these applications.
Likewise, once you log out of Gmail you get logged out of all other Google applications and this is called Single Logout
Mickey – I am getting this better.
Minnie – So if you unlock any one of the applications inside a system, you can access the other applications as well without authenticating yourself again.
Mickey – I am feeling so great
Minnie – So in one sentence you can say
“SSO helps to sign in to connected domains or applications with one username and password”
Mickey – Yes, I get it now.
Minnie – Oh! The train has arrived at your station.
Mickey – Oh, I just lost sense of time.
Minnie – All the best for your interview. I will wait here until you are back and we will take the train back home.
Mickey – You are my best friend
Minnie – I am always here for you 🙂
