Cryptography Encryption Secret Codes The Advance of Technology Copyright 2008 by Helene G Kershner Cryptography Encryption Since the dawn of written language people have used codes Secret CODE a system used for brevity or secrecy of communication in which arbitrarily chosen words letters or symbols are assigned definite meanings http dictionary reference com Codes and ciphers are forms of secret communication A code replaces words phrases or sentences with groups of letters or numbers A cipher rearranges letters or uses substitutes to disguise the message http www 42explore2 com codes html A cipher is an algorithm for performing coding encryption and decoding decryption character http en wikipedia org wiki Encryption Copyright 2008 by Helene G Kershner Cryptography Encryption Who uses secret codes Governments military businesses Doctors computer uses almost everyone Why bother To keep information private To protect information To protect ourselves or to initiate action One if by land two if by sea in Paul Rever s Ride in Longfellow s poem http en wikipedia org wiki Code cryptography The BBC broadcast personal messages such as The princess wears red shoes Mimi s cat is asleep under the table to direct actions by the French resistance during WW II http en wikipedia org wiki Code cryptography Copyright 2008 by Helene G Kershner Cryptography Encryption Long and mysterious history Codes used by ancient Hebrews Babylonians Egyptions Greeks and Arabs Caesar cipher a code developed by Julius Caesar that substituted each letter of the Roman alphabet for a letter 3positions down the list President Jefferson and Lewis Clark communicated in code when planning for their expedition The Morse Code is a set of dots and dashes that represents words Used heavily in both World Wars British built one of the first computers called Colossus to defeat the German coding system called Enigma Navajo code talkers served with the Marines in the Pacific http en wikipedia org wiki Encryption Copyright 2008 by Helene G Kershner Cryptography Encryption How might they work The Apple is Red Abc defghijk lmnopqrs tuvwxyz Using the Caesar cipher substitute for letters 3 down the alphabet THE APPLE is Red WKH DSSOH http en wikipedia org wiki Encryption Copyright 2008 by Helene G Kershner Cryptography Encryption Taken on new importance in the Computer Age Encryption is the process of obscuring information to make it unreadable without special knowledge To be sure a message is secret we need to know that the communication is secure it is received by the right people it can be decrypted or decipher In other words we must verify the integrity and authenticity of a message http en wikipedia org wiki Encryption Copyright 2008 by Helene G Kershner Cryptography Encryption The Government s Need to Know Vs The Right to Privacy Are these two ideas necessarily at odds Which should have higher priority Copyright 2008 by Helene G Kershner Cryptography Encryption In the mid 1970s strong encryption went from government agencies to the public domain WHY Copyright 2008 by Helene G Kershner Cryptography Encryption Where is it used if not by the government Encryption is now widely used anywhere where there are computers Password access to Internet sites Internet shopping e commerce Cellular messages Online banking and ATMs Code Makers Code Breakers 3 The Enigma History Channel http www youtube com watch v cGPRClA lok Code Makers Code Breakers 4 American Cryptology History Channel http www youtube com watch v GFLZyifnMuY feature related http secretcodebreaker com videos html Copyright 2008 by Helene G Kershner
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