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