Cryptography: Science of making and breaking codes i

To encrypt a message you need two main parts i.e. Cipher and the key.

Cipher is the set of rules that you’re using to encode the information for example, by shifting the alphabets to certain number of letters.

The key, tells you how to arrange those rules otherwise they would be same every time and it would be easy to decode the message. In this case the key would be one because we shifted the alphabet by one letter. To decrypt the information you need to know what kind of cipher was used and also have the key or you can just crack the code by trying all possible combinations you can think of or by analyzing the code and working backwards from it that is known as Deciphering. But is it possible to come up with a combination of cipher and key that could never be determined? Is there such a thing unbreakable code?

Well, people are coming with new and better ciphers but it is hard to make them unbreakable because no matter you are using a set of rules to encrypt the information, with enough time and data someone can usually uncover the rules of your encryption.

The oldest and simplest way to encrypt a message is known as Caesar Cipher. Well it is the easiest cipher to decode as well. You can easily decode the code because you just have to re-arrange the alphabets. Caesar Cipher is a simple Mono-alphabetic Cipher, a class of ciphers where the code is based on one letter of the alphabet standing in for another letter consistently throughout the message. Basically you just scramble the alphabet. In this case the key is which letter corresponds to which. 

There are over 400 septillion ways to encrypt this kind of message so would think it would be difficult to crack and it is, but only a little bit. Because there are a lot of ways to decode messages just trying all the possible keys to a word is the most obvious and least subtle with unsubtle name Brute Force. But you can try more sophisticated technique something called  Frequency Analysis which states that every language has its particular patterns.

In English, for example, The letter ‘E’ shows up a lot. I used it for 7 times in the last sentence. Some words like ‘The’ are so common that it is hard to use a sentence without them. Cryptographers called these words as ‘Cribs’. So frequency analysis look for common words or common letters or sets of letters just like “ed, ing” at the end of words.

Usually, with a variety of clues longer cryptograms are easier to crack. So mono-alphabetic ciphers are fun they are not hard to break. If you want be fancy about your encryption you can use Polyalphabetic ciphers instead, they are much more effective. In a polyaplhabetic cipher the way you scramble the alphabet actually changes through out the message. In the first word S might translate to W, In the last word S might translate to H. It all depends on the particular encryption method you are using and your Key.

Other encryptions and codes to be decoded in the next part. Till then Happy Reading