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Secret Codes

Secret Codes. A code is a system of symbols, letters, words, or signals that are used instead of ordinary words and numbers to send messages or store information. A code is used to keep the message short or to keep it secret.

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Secret Codes

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  1. Secret Codes

  2. A code is a system of symbols, letters, words, or signals that are used instead of ordinary words and numbers to send messages or store information. A code is used to keep the message short or to keep it secret. • Codes and ciphers are forms of secret communication. A code replaces words, phrases, or sentences with groups of letters or numbers, while a cipher rearranges letters or uses substitutes to disguise the message. This process is called encryption or enciphering. The science that studies such secret communication is called cryptology.

  3. Secret writing has been employed about as long as writing has existed. Codes have been used throughout history whenever people wanted to keep messages private. Cryptology has long been employed by governments, military, businesses, and organizations to protect their messages. Today, encryption is used to protect storage of data and transactions between computers.

  4. Pig Pen Code Scytale Messages/Cylinder Writing

  5. Lovell’s Cipher • Lovell's cipher, advocated by James Lovell of the Committee of Foreign Affairs, is one of many codes and ciphers used during the American Revolutionary War. • The following example shows a cipher table for a keyword "CR". This is the keyword assigned to John Adams. • 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 • C D E F G H I J K L M N O P Q R S T U V W X • R S T U V W X Y Z & A B C D E F G H I J K L • 24 25 26 27 • Y Z & A B • M N O P Q What does this message say? SMEQ DEFPQZED MCQ O&&X!

  6. Navajo Code Talkers in WWII • Code talkers were United States soldiers during the world wars who used their knowledge of Native-American languages as a basis to transmit coded messages. In particular there were approximately 400-500 Native Americans in the United States Marine Corps whose primary job was the transmission of secret tactical messages. Code talkers transmitted these messages over military telephone or radio communications nets using formal or informally developed codes built upon their native languages. Their service improved communications in terms of speed of encryption at both ends in front line operations during World War II.

  7. Enigma in WWI • Enigma was invented by German engineer Arthur Scherbius at the end of World War I. The early models were used commercially from the early 1920s, and adopted by military and government services of several countries — most notably by Nazi Germany before and during World War II.

  8. Other Examples of Codes • American Sign Language • Mirror Writing • Morse Code • Binary Code • Passwords • Combination Locks

  9. Resources • http://www.cerias.purdue.edu/education/k-12/teaching_resources/lessons_presentations/cryptology.html • http://www.nsa.gov/programs/kids/standard/lab/elementary/index.shtml

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