Page 1

‘In October 1586, in the forbidding hall of Fotheringhay Castle, Mary Queen of Scots was on trial for her life. Accused of treason and denied legal representation. she sat alone in the shadow of a vast and empty throne, belonging to her abscent cousin and arch rival Elizabeth the I of England. Walsingham Elizabeths principle secretary had already arrested and executed Marys fellow conspiritors, her only hope lay in the code she used in all her letters concerning the plot. if her Cipher remain unbroken she might yet be saved. not for the first time the life of an individual and the course of history depended on the arcain art of Cryptography.’


MARY QUEEN OF SCOTS


CONTENTS

Steganography ............................................................................... 1.

Cardarno......................................................................................... 7.

Caeser Cipher............................................................................. 11.

Arab Code breakers ................................................................... 13.

Mary Queen of Scots................................................................... 15.

Vigenere Cipher......................................................................... 19.

One Time Pad............................................................................. 21.


Before the inventions of cryptography people used steganography. With Cryptography people hid the message by scrambling it up so nobody can read it. it’s right there staring you in the face but nobody knows what it means. With Steganography you hide the exsistance of the message. Some examples of this include the chinese writing a message on silk, wrap the silk in wax and swallow it. the guard would check the messenger but wouldn’t find anything. The Greeks would shave a slaves head tatto the message onto the head let the hair grow back then the slaves head would be shaved to reveal the message. Another method would be to

get a wax tablet scrap off the wax write the message then reapply the wax to the message wouldn’t be visable Extreme methods would be to kill the messanger like a disposable messanger system, so that the messanger wouldn’t go tell anybody else. These techniques would also be used by The Babylons and Egyptians etc. The chinese would now be the only ones to still use steganography as their chracter system is a lot more complicated where as the roman alphabet its a lot easier to use cryptography

Simon Singh 01.21

1.


2.


3.


4.


5.


6.


7.


8.


9.


CARDANO CREATED A PIECE OF CARD WITH SMALL HOLES CUT OUT. SO YOU WRITE OUT YOUR LETTER BUT WHEN YOU PLACE THE CARD OVER IT YOU CAN ONLY SEE MAYBE SEVEN OR EIGHT KEY LETTERS SPELLING OUT A MESSAGE OF EXAMPLE THE LOCATION OF WHERE AN ATTACK MIGHT HAPPEN. IT CAN ALSO BEEN SEEN AS A FORM OF STEGANOGRAPHY. IT INVOLVES MAKING THE CARD, CUTTING OUT THE HOLES, WRITE THE TEXT MAKING SURE IT FITS, MAKE A COPY OF THAT CARD, GET THE CARD TO THE OTHER END SO THAT THEY CAN DECODE IT. ITS HARD WORK BUT ITS WORTH IT IF YOU’VE GOT A VALUABLE MESSAGE Simon Singh 25.22

10.


CR_TO _RAPH_

11.


When you have a roman or conventional alphabet it’s easy to take the letters and jumble them around to make a kind of anogram, also know as transposition, or to substitute the letters for different letters or symbols. That is where the transition happens, from Steganography where you’re hidding the exsistance of the message to Cryptography where you’re hiding the meaning of the message by jumbling the letters or substituting them. Cryptography came around at the time when people started to wrtie down information. people started to write down secrets. Whether it’s a personal diary, political, military, as soon as someone wirting down their sectret they need to find a way of hiding it. Simon Singh 03.14

12.


CAESAR CIPHER

The Caesar Cipher came about around the time of the Gallic wars. The first idea he had was to just change the alphabet, instead if writing in Roman letters justsimply substitute each Roman letter for a Greek letter, send it in Greek letters but with Roman

3 right would mean A would become D, B would become E and C become F and so on so by the end X would become A. So now what you see is a coded message which is what you call a cryptogram. This method held for a long time

meaning and you’ve

however with this

got your secret

method you only

message. All you need to decode is to now what

get 26 options. With the sustitution cipher you get to

happened. However

choose which letter is

people were unaware

substituted with which

that this was happening. Caeser used this during the Gallic wars to raise a seige with Cicaro. A Caesar shift Cipher involves shiffing the letters across so many spaces for example shift

13.

so A could become Q and B become T. so now instead of 26 keysyou’ve got 400,000,000,000,000,000,00 0,000,000. This method held for 900 years. (Fred Piper 05.22)


I A I ZCTM, UMV EWZZG U W Z M IJWCB EPIB BPMG KIV’BAMM B P I V IJWCB E P I B BPMG KIV. ‘RCTQCA KIMAIZ’ SHIFT KEY 8

14.


VIGENERE CIPHER With the Vigenere there are 26 different keys you shift from 1,2,3,4 up to 26. You have a square, on each side of the square reads the letters A-Z then within that square you have 26 versions across and down of the alphabet, so you’ve got a square with multiple letters inside. The first column would be B-A, second column C-B third column D-C and so on. So the first row would be the Caesar Cipher shift 1, second row Caesar Cipher shift 2 and Caesar Cipher shift 3 up to Caesar Cipher shift 25. Then you agree on a sequnce of numbers lets say 137, you use first row first and third row second and seventh row third. The amount of numbers you use is the number of Ciphers. By using this method it breaks the frequency analysis. unfortunately the publication of the Vigenere Cipher was the year after Mary Queen of Scots was executed. you can also use code words for example pen so you

21.


use the P Cipher, then E, then N. Again the complexity of your code will depend on the number of letters in the word.say you have the word DOG with the Caesar Cipher and you shift it one space so D becomes E, O becomes P and G becomes H. If someone were to know that it was Caesar Cipher all you have to do is try 25 different shifts all you’ll get the message. With the Vigenere Cipher you have 26 cubed different ways. What you’re trying to do is break up the patterns. Language has rich patterns such as word lengths and vowel relationships, you’re trying to get from a very rich patterned message to something that looks completely random, has no pattern nor structure. Code breakers devour patterns and structure to get to the original message, so you’re always trying to break up that pettern and thats what a Vigenere Cipher does.

22.


FREQUENCY ANALYSIS One way to solve an encrypted

occurrences of each letter..

most occurring letter the ‘third’,

message, if we know its language, We call the most frequently

and so on, until we account

is to find a different plaintext of the occurring letter the ‘first’, the

for all the different letters in the

same language long enough to

plaintext sample.

fill one sheet or so, and then we count the

next most occurring letter the ‘second’ the following

Then we look at the cipher text we want to solve and we also classify its symbols. We find the most occurring symbol and change it to the form of the ‘first’ letter of the plaintext sample, the next most common symbol is changed to the form of the ‘second’ letter, and the following most common symbol is changed to the form of the ‘third’ letter, and so on, until we account for all symbols of the cryptogram we want to solve. Lisa Jardine 09.12

15.

(can you reveal the message opposite?)


16.


MARY QUEEN OF SCOTS Anthony Babington was a young

Walsingham waited and gathered

Catholic noble who joined a plot

evidence that would implicate

to depose the Protestant Queen

Mary in a plot against Queen

Elizabeth I and put Mary Queen

Elizabeth.

of Scots on the English throne.

On 28 June 1585 Babington

Sir Francis Walsingham, the

wrote to Mary outlining a plot

head of Elizabeth’s secret

to murder Elizabeth and release

service, captured a Catholic

Mary with the support from an

plotter named Gilbert Gifford

invasion from Spain.

and ‘convinced’ him to act as a

Myself with ten gentlemen and

double agent. Gifford would act

a hundred of our followers will

as an intermediary smuggling

undertake the delivery of your

letters to Mary who was

royal person from the hands of

imprisoned in Chartley Hall.

your enemies.

All the letters were given to

For the dispatch of the usurper,

Walsingham. The letters were

from the obedience of whom we

written in a secret code called ‘a

are by the excommunication of

nomenclator cipher’. Walsingham

her made free, there be six noble

had the code deciphered.

gentlemen, all my private friends,

17.


who for the zeal they bear to the Catholic cause and your Majesty’s service will undertake that tragical execution. Extract from Anthony Babington letter to Mary, June 1585 Mary’s reply was intercepted and sent to Walsingham. It was sealed with a drawing of a gallows. Walsingham had the evidence he needed. Babington and the other plotters were arrested, tortured, tried and condemned to be hanged, drawn and quartered. The damning evidence of the letters between Mary and the plotters was presented to Queen Elizabeth. It was only a matter

18.


The details are slightly murky because you’re never quite sure what really happened and what was set up for historians to later discover. One version of events is that mary is communicating with plotters who are trying to release mary from prison and assasinate Elizabeth and they use a code, because these are clearly treturous attempts on the life of a queen. This code is not very different from

19.


the codes with which Al kindi used the Frenquency analysis. They used symbols and shapes for example they’re going to swap A for a diamond B for a square, c for a cross. they throw in some nice details, they throw in some red herrings, spurious characters which just pepper the Cipher which would confuse a potential code breaker they throw in a character that doubles the previous one so if you’re doing bottle you

to the code breaker and dispite

put something after the tea to

all these little embroiderys

double the t. these message

around the code you just count

are sent to and fro where Mary

the letters, see which ones are

replies back and says ‘yes lets

most common and you break

go for it, i’m on board with

the code. There infront of you

this plot’. Unfortunately the

Elizabeths spymaster see’s a

person delivering this message

letter which proves un-doubtably

is a double agent, Gifford,

that Mary is involved in a plot to

so whenever Gifford gets a

assasinate Elizabeth

message he takes it to Elizabeths spy master, Walsingham, who

simon sing 17.02

makes a duplicate and gives it

20.


ONE TIME PAD The One Time Pad is absolutelyunbreakable, it’s guarenteed rock solid, if you encrypt a message with the One Time Pad and a I sent it to Fred and MI5 tapped our phone line they would never be able to break it. Thats why its so important, so wonderful. what you do is you write out you letter and take every single letter, for example you have a sequence of 100 letters and you’re going to shift every letter but every shift for each letter is going to be completely random. Before i encrypt the message, imagine you’ve got a 26 sided dice I roll the dice 100 times so i get a sequence of 100 random shifts, the first is going to maybe be shifted by ten places the second by four the third by eighteen and so on and because every shift is completely random the output is completely random and the code breaker has absolutely no patterns, almost the definition of random is something without any pattern or structure and thats why you cannot break it. Simon singh 31.34

23.


However there are short comings. Let’s suppose you’re in austrailia and i’m in England. I have used the One Time Pad method. I send you the cryptogram what can you do with it? absolutely nothing until you know those random numbers i’ve added so you can take them off. so we’ve still got the problem of the messanger getting what you call the key, getting this random sequence to you. In certain scenarios that isn’t too difficult. The London Washington hotline is on that you can send in advance and you just tell them which one you’re using. So you will have say 1000 random sequences that you’ve sent earlier by very secure means. So the problem is the extra material you send to protect your messages is as much material as the message itself. The name One Time Pad gets its name because the code is used once then destroyed.

Thats the beauty of the One Time Pad because as soon as you repeat anything in a cipher, you run the risk of being decoded. Repetition is the bug bear of any pattern, If you use the one time pad twice someone will notice. It’s very difficult for a person to generate randomness. The Enigma is a machiene enciphering machine developed for commercial use in the early 1920s and later adapted and appropriated by German and other Axis powers for military use through World War II. It electricly and mechanically generates multiple patterns of randomness but in ways that can be undone, reversed at the other end so if somebody has a machine at the other end, this mechine has the capacity of reversing immediatly all the complexity that you put in randomly when you encoded the message. The phrase use is ‘Sudo’ randomness.

Fred Piper 32.42

Lisa Jardine 33.45

24.


25.


cryptography  

a publication translating and transcribing the radio 4, in our time programme on Cryptography