“CRYPTOGRAPHY — Making sense out of the unintelligible”

It’s been more than a thousand years, since the cryptography came into existence and maybe even more. Kings, Queens and Generals have relied on efficient means of communication in order to govern and command their armies. They were totally familiar with the consequences of their messages falling into the wrong hands, revealing precious information to enemies and rival nations. It was actually this threat of the vital information being intercepted by the enemies that led to the development of codes and ciphers: techniques and ways of disguising a message so that it seems unintelligible and makes sense to the intended recipient only. The desire to attain secrecy meant that the code-making departments had to be formed by nations to achieve the goal in view, who would be responsible for ensuring security to communications by inventing and implementing the best possible codes. At the same time, code-breaking ran parallel to code-making. Codebreakers always attempted to break the enemies codes and tried to steal secrets.

Codebreakers are linguistic alchemists, a mystical tribe attempting to conjure sensible words out of meaningless symbols — writes Simon Singh in THECODEBOOK.

A code is constantly under attack by codebreakers trying to identify it’s weaknesses. When codebreakers develop a new method that reveals a code’s weakness, then the code is no longer useful or of any importance. It either extincts completely or evolves into a new stronger code. The notion of extinction of a particular code has almost vanished, as the development in codes to make them resistant to attacks have grown with the evolution of the several new code-making techniques. There’s a battle going on between codemakers and codebreakers that inspired some remarkable scientific breakthroughs. The codemakers have been and are continually striving to construct even stronger codes for defending communications, while codebreakers have almost always invented even powerful methods for attacking them. The battle is still going on.

Cryptography being the science of secret writing or the art of secret communication, has been a key factor in almost everything. History is accentuated with codes and ciphers. History tells us how choosing a weak cipher lead to the execution of “Mary Queen of Scots” for high treason, and that of “The German Enigma” invented by “Arthur Scherbius” who thought Enigma was impregnable. The history of Codes is so inordinately rich that it leaves everyone awestruck. From the tales of “Da Vinci” or “Geoffrey Chaucer” to the heroics of “Alan Turing”. From Caesar’s Cipher to Quantum and Post-Quantum Cryptography it has evolved through times with grace. It continues to amaze people with the basic foundations of these ciphers and the things that rely on it.

It’s being said that the First World War was the Chemist’s war, because of the use of mustard and chlorine gas for the first time, and that the Second World War was the physicists war, because the atom bomb was detonated. In that context, it has been argued by many that the Third World War would be the mathematicians war, because the mathematicians will have control over the next great weapon of war — information. It’s that mathematicians that have been responsible for developing the codes currently used to protect information. Flabbergastingly, it’s the mathematicians that are at the forefront to break these codes.The first known European book to describe the use of cryptography was written in the thirteen century by the English Franciscan monk and polymath “Roger Bacon”. “Epistle on the Secret Words of Art and the Nullity of Magic”. It included seven methods for keeping messages secret, and cautioned:

'A man is crazy who writes a secret in any other way than one which will conceal it from the vulgar’.

Information being a valuable commodity, and as the communication revolution changes every now and then, so does the process of encoding messages, known as encryption which plays an important role in everyday life. The networks we are surrounded with show us the beauty of cryptography. From phone calls to emails that pass through various computers, they form a communication network which would’ve been intercepted with ease thus jeopardising our privacy but with cryptography in our hands, everything transmitted along these networks is encrypted and can be decrypted only by the intended recipient.

Cryptography in essence is more than the codes, ciphers and crossword puzzles.

Cryptography itself can be divided into two branches, known as transposition and substitution. In transposition, the letters of the message are simply rearranged, thereby generating an anagram. This method is insecure for short messages because of the limited number of ways of rearranging the letters. A form of transposition was seen being embodied on the surface of the first ever military cryptographic device, “the spartan syctale” from the fifth century B.C.

The alternative to transposition is substitution. One of the earliest descriptions of the encryption using substitution appears in the “Kāma-sūtra” a text written in the fourth century AD by the Brahmin Scholar Vātsyāyana. From the techniques of transposition and substitution to the use of number theory, cryptography with every transition has seen mathematics playing the central role of importance in the underlying primitives.

Mathematics is as important to the strong use of cryptography as bits are to computers.

A various number of fields in cryptography has emerged with time. We have Symmetric, Asymmetric, Quantum, Post Quantum,Homomorphic, Lattice based and Lightweight cryptography as some of the fields. Extensive research is being done across all the fields using the interdisciplinary approach. Symmetric cryptography involves the use of a key known as the “secret key” which is used in the process of encryption and decryption. While as the Asymmetric cryptography approach involves the use of two keys rather than one. Private key and Public key. As the name suggests, Public key is kept open to public along with the algorithm used while the private key is private for the communicating parties involved.

One of the basic principles of modern cryptography is known as the “Kerchoff’s principle” which states : that the strength of the encryption algorithm used, should totally depend on the key even if the algorithm is made public.

The involvement of Cryptography is almost everywhere, from our browsers to our mobile phones, everything is embodied with cryptography. From the use of groups and fields in the symmetric and assymetric cryptography to the use of lattices in Lattice based Cryptography. Cryptography has seen it all. As we are almost in the age of Quantum computers, the research is being conducted to make sure that the available cryptographic primitives stand the attacks from the computing power of Quantum computers. The Post-Quantum era is being looked upon as a strong contender to the Quantum era.

With the increase in computing power, the attacks on the primitives are increasingly rapidly. With Quantum computers in view, it’ll be the test of primitives in use and so will be of those relying on those primitives including the commercial market and the national security.

Bruce Schneier gave us an idea about choosing our sort of encryption that we can rely on:

There are two types of encryption: one that will prevent your sister from reading your diary and one that will prevent your government.

It’s your job to choose your type of encryption. Though you’re not sure of when it’ll be broken. As Noam chomsky said:

Somebody will be able to overcome any encryption technique you use!



I used to be a Researcher sometime back, now I write code for a living. Backend Engineer

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store
Aaqib Bashir

I used to be a Researcher sometime back, now I write code for a living. Backend Engineer