Week 11 Secret Codes of the Middle Ages COMPILED BY AMY.

Week 11Secret Codes of the Middle AgesCOMPILED BY AMY

Ancient Code

Steganography

Hides the existence of the message.

This can use “invisible ink”

Cryptography - Transposition

Makes the Messge hard to read.

Use transposition by rearranging the letters.

Plaintext A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Cipher D E F G H I J K L M N O P Q R S T U V W X Y Z A B C

Cryptography - Substitution

Code

Substitutes a word or idea

Cipher

Substitutes by letter

Monoalphabetic uses one letter to equal one symbol

Polyalphabetic uses several possible symbols to represent one letter

Homophonic – some letters have several choices

Cipher Polybius Square

1 2 3 4 5

1

A B C D E A = 11

2

F G H I/J K B = 12

3

L M N O P M = 32

4

Q R S T U Z = 55

5

V W X Y Z ...

Leon Battiste

Polyalphabetic Substitution

http://crypto.interactive-maths.com/polyalphabetic-substitution-ciphers.html

Cryptex

Made up by Dan Brown in the Davinci Code!

It is like a bicycle lock and if you get it wrong…

It will release acid that will destroy the message.

Some Unbreakable Codes

http://www.newscientist.com/special/unbreakable-codes

Making Your Own Cypher!

http://hldennis.com/secrets-to-break/secrets-to-break-book-three/

Cool Websites

http://www.stringpage.com/other/crypto.html

http://www.ciphermysteries.com/2008/06/01/codes-and-ciphers-through-the-middle-ages

http://www.kidsmakestuff.com/articles/show/18hm