What is Encryption?

The use of encryption to disguise the meanings of messages goes back thousands of years (the Romans, for example, used substitution ciphers, where each letter in a message was replaced with a different letter). Mechanical cipher machines first came into general use in the 1930s. During World War II the German Enigma cipher machine used multiple rotors and a configurable plugboard to create a continuously varying cipher that was thought to be unbreakable. However, Allied codebreakers built electromechanical and electronic devices that succeeded in exploiting flaws in the German machine (while incidentally advancing computing technology). During the cold war Western and Soviet cryptographers vied to create increasingly complex cryptosystems while deploying more powerful computers to decrypt their opponent’s messages.

In the business world, the growing amount of valuable and sensitive data being stored and transmitted on computers by the 1960s led to a need for high-quality commercial encryption systems. In 1976, the U.S. National Bureau of Standards approved the Data Encryption Standard (DES), which originally used a 56-bit key to turn each 64-bit chunk of message into a 64-bit encrypted ciphertext. DES relies upon the use of a complicated mathematical function to create complex permutations within blocks and characters of text. DES has been implemented on special-purpose chips that can encrypt millions of bytes of message per second.