Another form of encryption is called the Vigenère cipher, which uses multiple Caesar ciphers. It requires two people to agree on a key for them to decrypt each other's messages. This method was broken in the mid-1800s by Charles Babbage and William Kasiski. The Vernam cipher, named after its creator Gilbert Vernam, uses as many Caesar ciphers as there are letters in the message. This type of encryption is also known as a "one-time pad", because it can only be used once, and then must be thrown away to ensure security of messages. This type of cryptography was used in WWII by the Soviet KGB and in the Cold War. During WWII, the Soviet KGB had reused one-time pads, which allowed the U.S. and Britain to decrypt three thousands on messages. This is the only known way to break the Vernam cipher. Otherwise, if only used once, is unbreakable. |
| Example of a "one-time pad" |
Today, modern encryption is based off of ciphers from ancient substitution methods. Old methods were used in recent years by criminals such as Bernardo Provenzano, the head of the Sicilian Mafia, who sent messages encoded in Caesar cipher to his son. In 1999, huge wireless companies were still using and selling outdated WEPs (Wireless Equivalent Privacy) - which was very insecure and flawed - even when WPAs (Wi-Fi Protected Access) became available 3 years later. By the time all electronic devices were required to switch over to WPA in September 2003, more than $45 million worth of credit and debit card records had been intercepted and stolen by hackers. So by the time the 19th and 20th centuries came around, more and more Americans had started to turn to cryptography to shield themselves from violations of privacy.
In the late 20th century, there was a shift in the purpose of cryptography. It went from being a government weapon to a consumer good. Encoded public messaging came into play, and a secure way to send private, yet public, messages, was found by Whitfield Diffie, Martin Hellman, and Ralph Merkle. Before, keeping the key to decrypting encrypted messages had been the major goal. However, once these men (and James Ellis, Clifford Cocks, and Malcolm Williamson before them) found a way to agree on a key without meeting beforehand, cryptography was changed forever. The Diffie-Hellman-Merkle method employed the concept of "one-way computation". In brief summary, person A would choose a secret number a and person B would choose their secret number b. Then they would both compute their own public keys, by multiplying a commonly known number g with their secret number. Then they would send their computed numbers to the other. The receiver would multiply the sender's computed number with their secret number (either a or b) and that way they could produce and agree on a key, without ever meeting in person.So far, the Diffie-Hellman-Merkle method has not been broken, and most likely never will be. However, it is still possible to break, so another method was created by Ron Rivest, Adi Shamir, and Len Adleman: RSA (using the first initials of all their last names). It is used to create digital signatures (digital signatures are created to prevent forgery and impersonations and provide verification of validity) and private messages, using one-way computation as well, but in a different way that is slower to decrypt, and thus stronger and less breakable.
