Introduction to Cryptography (Non-Technical)

(Notes: I’ve been having some interesting debates with a friend lately, and one of the things we did agree upon is the lack of resources in cryptography that the public can easily understand. Well, it is common knowledge that there are discussions in the security community that the best security defense is an educated user. However, there are very few materials on the subject for non-technical users specially on the subject of cryptography. So, I decided to post a series of articles about cryptography (and, maybe, eventually about cryptographic systems and infrastructures) where in I will try to explain it in non-technical terms. For this article, I decided to start with an introduction to cryptography. Here goes…..)

Introduction to Cryptography

Cryptography is such a big word and to understand it better, it would be helpful to know the origin of the word. It came from 2 Greek words Kryptos meaning “hidden” (from kryptein meaning “to hide”) and Graphos meaning “writing”. So, basically, cryptography is secret writing or obscure writing where the message is “hidden” in such a way that only the right person will be able to read it. And for that person to be able to read the right message, he needs to unlock it. And every kind of cryptography is centered around the idea of a “key”.

Think of it this way, the exchange is like buying a house. The situation is this, the seller gave you the location of the house with you being the right receiver. So to be able to open the house, you should have the key to the front door (assuming that it is the only door where you can use a key). This concept is called “decryption”, where the user will see the contents using his key. The reverse of this process is called “encryption” where the sender of the house locks the front door (and every other entrance). Now, in cryptographic terms, the seller is the “sender” of the “cipher text or encrypted message” which is in this example is the house and you being the new owner is the “receiver” of the message. The by unlocking the front door, you can now see the contents of the house which is referred to, in cryptography literature, as the “plain text or the decrypted message”.

Now, let’s say somebody named Eve had been eavesdropping on your conversation and got the location of the house. Now, she plans to steal the contents of your new house. However, since she doesn’t have the key, she will have to break-in to the house. This is called “cryptanalysis” where the “cryptanalyst” tries to break-in using different techniques. In this scenario, Eve can use the backdoor, the windows and even the front door.

Basically, the role of the “cryptographer” is to keep the house secured by making the lock system, as much as possible, unbreakable to keep “cryptanalysts” from breaking-in.

Cryptography wasn’t just invented yesterday. On the contrary, it was even used during the time of Caesar. There were many techniques that were employed through the ages. To this day, the cryptographers and cryptanalysts have been inventing and re-inventing techniques to outwit one another. Throughout the years, it had been a race between “cryptographers” and “cryptanalysts”. Both the security and intelligence communities seem to agree that the real war zone of World War II were on dark rooms where the ones that were fighting holds neither guns nor bombs but knowledge on mathematics, cryptography and cryptanalysis.

Three decades ago, cryptographers around the world were joined by physicists and had started to talk about cryptography bounded not only by mathematical laws and theories but the laws of nature as well. Physics, in theory, will provide the ultimate security that cryptanalysts may never be able to break. However, we will find that, right now, the most ideal equipments to provide the security parallel to that in theory exists only in the physicists’ mind. And with its’ imperfection, the cryptographic community may find itself the testing ground for new cryptanalysis techniques that may someday beat not only mathematics but physics as well.

Next Article on this Series: Earlier Forms of Cryptography (Non-Technical)

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