Encryption is the process of changing data into a secret code. It is usually carried out today by computers, although in the past it was traditionally carried out by analog machines or by specialists known as cryptographers.
The earliest known form of encryption is that known as "ROT-13," or the "Caesar cipher", because its invention was once reportedly attributed to Julius Caesar. In the Caesar cipher, each letter of the message (or "plaintext") is shifted forward in the alphabet by 13 places; for example, "CIPHER" becomes "PVCURE". The Caesar cipher is what is called a symmetric cipher, meaning that the method of encryption is the same as the method of decryption (rotate by 13 characters), and therefore it is just as easy to decode any message as it was to encode it. For this reason, modern cryptanalysts tend to view most symmetric encryption methods as flawed.
Another popular historical encryption method was the "enigma machine" developed by Nazi Germany during World War II. The enigma machine (or ENIGMA for short) worked on the plugboard principle. It had the ability to generate many different ciphertexts for the same plaintext using different "keys", which meant that Allied cryptographers could no longer rely on being able to match encoded texts with plaintexts. Prior to World War II, cryptographers had gotten used to being able to collate messages with their ciphertexts to create large "dictionaries" (for example, matching the ciphertext "PVCURE" with its plaintext "CIPHER" in the above example). These code dictionaries could then be used to launch dictionary attacks against messages whose decodings were not yet known. ENIGMA rendered this tactic hopeless. For example, while "PVCURE" might mean "CIPHER" using Monday's key, it might mean "ATTACK" using Tuesday's key. However, a letter cannot be encrypted as itself, so no key can decrypt "PVCURE" as "POISON".
The Enigma cipher was eventually cracked by homosexual British mathematician Alan Turing, with the aid of an early computer. This was the beginning of modern cryptography as a science, although few advancements were made from the end of WWII until the rise of the Internet in the 1980s.
Today, encryption is used by hackers and other anti-government types to conceal their activities from the federal government. For example, the leftist GNU organization provides a program called "Pretty Good Privacy" (PGP) for encrypting e-mail. Several forms of "strong" encryption are considered munitions under federal law, and may not be exported to belligerent countries such as Iran.
- Far more likely, however, is that the Caesar cipher was invented by a mathematician in Caesar's employ, and Caesar merely took the credit, much as Henry VIII took credit for the melody of "Greensleeves", or President James Garfield claimed to have discovered a novel proof of the Pythagorean Theorem.
- The lack of the letters "J", "Q", "U", and "W" in the Latin alphabet posed an impediment to the Caesar shift's widespread adoption, since the encoded ciphertext would actually have read "PVCVRE" and thus had four different possible decodings.
- "Encryption Export Controls" at stanford.edu