What is Cryptography?

What is Cryptography?

• A very basic and classical goal of Cryptography is enabling secret communication between two parties, even in the presence of an adversary.
• In the early days (before 1970), this was achieved through various mathematical tricks and methods that were often not very scientific in nature.
• In contrast, modern cryptography is grounded in a solid mathematical foundation and is regarded as a branch of engineering that lies at the intersection of mathematics and computer science.

Ancient cryptography vs Modern Cryptography

Cryptography has been utilized in various forms since ancient times, with evidence suggesting its use as far back as 1900 BC. The Ancient Greeks developed structured cryptographic methods that included ciphers, laying the groundwork for modern secret-key encryption to transmit confidential messages. One notable example is the Caesar Cipher, used by Julius Caesar around 100 BC, which replaced each letter in the English alphabet with a letter shifted three places over; for instance, ‘A’ became ‘D’, ‘B’ became ‘E’, and so forth. This shift was known only to Caesar and his trusted generals.

In 1553, Giovan Battista Bellaso introduced a generalized version of the Caesar Cipher, which gained traction in the 19th century through Blaise de Vigenère, subsequently becoming known as the Vigenère Cipher.

Compared to the Caesar Cipher, which can be easily deciphered by determining the correct shift (or key), the Vigenère Cipher offered significantly enhanced security and difficulty in breaking.

The evolution of cryptography continued with Edward Hebern’s invention of a rotating machine for encryption in 1917, followed by the famous Enigma Machine created by German engineer Arthur Scherbius in 1918. This machine was widely used by the Nazi German military during World War II until its cipher was cracked by Polish and British cryptographers who designed the “Bombe” machine for decryption.

Initially, cryptography was primarily associated with military use. However, in 1970, IBM developed a cipher known as Lucifer, marking a shift towards a more systematic and scientific approach in cipher design. This work eventually led to the creation of the Data Encryption Standard (DES), representing a significant milestone in the field of Modern Cryptography.