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