Читать книгу Cryptography, Information Theory, and Error-Correction - Aiden A. Bruen - Страница 42

Since the early stages of human civilization, there has been a need to protect sensitive information from falling into the wrong hands. To achieve such secrecy, mankind has relied on a branch of mathematics known as cryptography, which is the study of designing methods to securely transmit information over nonsecure channels. In order to achieve this goal, one must first encipher, or scramble, the intended message to prevent an eavesdropper from obtaining any useful information, should the message be intercepted. The message (referred to as plain text) is scrambled into cipher text using a predetermined key, known to both the sender and receiver. The encrypted message is constructed in such a way so as to be resilient against attack, while allowing the intended recipient to decipher, or unscramble the message with ease. The methods we will be investigating in this section to accomplish this task may be outdated and in some cases obsolete, but they can still provide us with valuable insight into some techniques that are still in use today.