Confidentiality with Encryption

We already discussed a bit about encryption in our previous article. So at least many of us now know about cipher texts. No worries even if you don’t know. Let’s dive a little deep into this topic here.

Let me introduce you to the two well known personality in security paradigm, Alice and Bob. Both of them are working on a super secret mission called Phantom. They don’t discuss anything about the mission on phone calls. Both of them agreed upon communication through handwritten letters. They decided a secret place where the letter could be dropped and received. The idea worked well for a few months. But then Mr Eve got hired by an agency which was trying to steal the conversation between Alice and Bob. Mr Eve, smart enough, was able to find the secret place where the letters used to be dropped and received. And the consequence, mission Phantom started facing serious setbacks.

Alice and Bob had to revise their strategy now. They did some brainstorming and came up with an excellent idea. Both of them went to market and bought a robust, strong and unbreakable box made up of Vibranium (For those who don’t know, Captain America’s shield was made up of this material) and a lock made up of same material with two keys. Each of them was in possession of a key now. Whenever Alice has to send some message to Bob, he would write a letter, keep the letter in the box and lock the box using the key and lock he possessed. The next task was to courier or post the box to Bob. Once received, Bob would use the key he possessed to open the lock (because the lock worked only with two keys, one with Alice and the other with Bob), take out the letter from the box and read the message. And Bob would do the vice versa if he wanted to send any message to Alice.

Mr Eve was helpless now. Why ?

He tried stealing the box a few times and open the lock, but all in vain. Because the lock could only be operated upon by the two keys that came along with it. And since the box and lock was impossible to tamper with, the poor guy couldn’t read the messages even after stealing.

This whole process where the message from Alice to Bob was a secret and could only be read by Bob is called confidentiality. And how this confidentiality is achieved? By Encryption of course.

What is Encryption ?

Process of converting a plaintext to a ciphertext (a random text which has no meaning ). The ciphertext has information about the plaintext, but nobody without proper authorisation can get that information.

And who is authorised to get that information?

Anybody who has the key to decrypt the information.

In the above example, Alice and Bob used to hide their letters into the box and lock it using their key. The box contained the letter, Mr Eve knew that. But he couldn’t get that letter from the box because he wasn’t authorised for that. Why he wasn’t authorised? Because he didn’t have the key to the lock.

Alice would use a key to encrypt his message. Bob would use his own key to decrypt the message. Mr Eve, even though he steal the encrypted message, couldn’t do anything with that because he couldn’t decrypt the message by any means. And remember, the encryption used was so strong that it couldn’t be break.

With the information above, I hope everybody understands encryption now. Of course there would be many questions like..

What would be the key in computing world?

How the plaintext would be converted to ciphertext using that key?

Would the same key which was used for encryption be used for decryption too?

I am gonna answer all that in the next article of this series. Stay tuned….