A BRIEF HISTORY OF SECRET WRITING

Secret Writing

(hidden writing) (obfuscated writing)Steganography Cryptography

A Brief History of

EXAMPLES OF HIDDEN WRITING

STEGANOGRAPHY

480 BC - hidden writing in behind wax tables - used to warn Sparta of an incoming attack from Xerxes of Persia

EXAMPLES OF HIDDEN WRITING

STEGANOGRAPHY

Weird Chinese thing• Write message on silk • Ball up silk, and coat in wax • Eat ball • ??????????????????? • Profit

EXAMPLES OF HIDDEN WRITING

STEGANOGRAPHY

Invisible ink• Typically organic, e.g. thithymallus milk • Dries transparently but chars easily when heated • Sometimes is wee

https://commons.wikimedia.org/wiki/File:Manneken_Pis_in_judopak_Brussel.jpg

EXAMPLES OF HIDDEN WRITING

STEGANOGRAPHY

Microdots

We need to buy an elephant to keep the city free from the things

that are scared of elephants and the future they foresee

LAST YEAR WE BOUGHT A RHINO

WITH BUT ONE FATAL FLAW THERE WAS NO

INTIMIDATION IN THE FUTURE HE FORESAW

END

HIDING THE MEANING OF A MESSAGE

CRYPTOGRAPHY

Teeshirts and Sunglasses Time slows down

As I'm walking on the sand Skimming Stones

ENCRYPT

Grrfuvegf naq Fhatynffrf Gvzr fybjf qbja

Nf V'z jnyxvat ba gur fnaq Fxvzzvat Fgbarf

DECRYPT

Teeshirts and Sunglasses Time slows down

As I'm walking on the sand Skimming Stones

HIDING THE MEANING OF A MESSAGE

CRYPTOGRAPHY

Secret Writing

CryptographySteganography

Transposition Substitution

RAIL FENCE

TRANSPOSITION CIPHERS

THE WAY SHE MOVES IS KIND OF COOL SHES FIXING HER VW

T E A S E O E I K N O C O S E F X N H R W

H W Y H M V S S I D F O L H S I I G E V

TEASEOEIKNOCOSEFXNHRWHWYHMVSSIDFOLHSIIGEV

SCYTALE

TRANSPOSITION CIPHERS

Lysander of Sparta vs Pharnabazus of Persia, 5th century BCE

https://en.wikipedia.org/wiki/File:Skytale.png

SIMPLE SUBSTITUTION CIPHERS

SUBSTITUTION CIPHER

Caesar (shift) Cipher

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 zw x y z a b c d e f g h i j k l m n o p q r s t u v

plaintextciphertext

JMVWX MQ SR XLI SYXWMHI EW MQ PSSOMRK EX XLI GIRXVIILUVW LP RQ WKH RXWVLGH DV LP ORRNLQJ DW WKH FHQWUHKey -1HKTUV KO QP VJG QWVUKFG CU KO NQQMKPI CV VJG EGPVTGKey -2GJSTU JN PO UIF PVUTJEF BT JN MPPLJOH BU UIF DFOUSFKey -3FIRST IM ON THE OUTSIDE AS IM LOOKING AT THE CENTREKey -4

Caesar cipher is limited to 25 keys

SIMPLE SUBSTITUTION CIPHERS - INCREASE THE KEYS

SUBSTITUTION CIPHER

Generate far more potential keys by pairing letters in random order

plaintextciphertext

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 zh i j

x d k l g n q p o r m t u v w i y z a b c j e f s

• 400000000000000000000000000 (400 septillion) possible keys!

• But all users have to know the custom alphabet

• Use a keyword or phrase to make it easy to remember whilst still keeping the number of potential keys high

SIMPLE SUBSTITUTION CIPHERS - MEMORABLE KEYS

SUBSTITUTION CIPHER

plaintextciphertext

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 zn i j

o r t h w e s d u p a l g i j k m q v x y z b c f

Northwest Drupal User Group

northwestdrupalusergroup

northwesdupalg

ENTER THE ARABS

V

Frequency Analysis53‡‡†305))6*;4826)4‡.)4‡);806*;48†8¶60))85;;]8*;:‡*8†83(88)5*†;46(;88*96*?;8)*‡(;485)5*†2:*‡(;4956*2(5*—4)8¶8*;4069285);)6†8)4‡‡;1(‡9;48081;8:8‡1;48†85;4)485†528806*81(‡9;48;(88;4(‡?34;48)4‡;161;:188;‡?;

https://en.wikipedia.org/wiki/The_Gold-Bug#/media/File:Zlaty_brouk_-_frekvence_pismen.svg

https://en.wikipedia.org/wiki/The_Gold-Bug#/media/

File:English_letter_frequency_(frequency).svg

ENTER THE ARABS

CRYPTANALYSIS VS CRYPTOGRAPHY

Frequency Analysis53‡‡†305))6*;4826)4‡.)4‡);806*;48†8¶60))85;;]8*;:‡*8†83(88)5*†;46(;88*96*?;8)*‡(;485)5*†2:*‡(;4956*2(5*—4)8¶8*;4069285);)6†8)4‡‡;1(‡9;48081;8:8‡1;48†85;4)485†528806*81(‡9;48;(88;4(‡?34;48)4‡;161;:188;‡?;

A good glass in the bishop's hostel in the devil's seat twenty-one degrees and thirteen minutes northeast and by north main branch seventh limb east side shoot from the left eye of the death's-head a bee line from the tree through the shot fifty feet out

The Gold Bug, Edgar Allen Poe

MARY QUEEN OF SCOTS

THE BABINGTON PLOT

JAMES V OF

SCOTLAND

MARGERET TUDOR

QUEEN ELIZABETH

I

MARY QUEEN OF

SCOTS

MARY OF GUISE

ANNE BOLEYN

HENRY VII ELIZABETH OF YORK

JAMES IV OF

SCOTLANDHENRY VIII

FIRST COUSINS ONCE

REMOVED

MARY QUEEN OF SCOTS

THE BABINGTON PLOT

MARY QUEEN OF

SCOTS

ANTHONY BABINGTON

CONSPIRATOR

CONSPIRATOR

CONSPIRATOR

CONSPIRATOR

CONSPIRATOR

CONSPIRATOR

GILBERT GIFFORD

SIR FRANCIS WALSINGHAM

QUEEN ELIZABETH

I

MARY QUEEN OF SCOTS

THE BABINGTON PLOT

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TURNING IT UP TO 26

VIGENERE CIPHER

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 zb c d e f g h i j k l m n o p q r s t u v w x y z ac d e f g h i j k l m n o p q r s t u v w x y z a bd e f g h i j k l m n o p q r s t u v w x y z a b ce f g h i j k l m n o p q r s t u v w x y z a b c df g h i j k l m n o p q r s t u v w x y z a b c d eg h i j k l m n o p q r s t u v w x y z a b c d e fh i j k l m n o p q r s t u v w x y z a b c d e f gi j k l m n o p q r s t u v w x y z a b c d e f g hj k l m n o p q r s t u v w x y z a b c d e f g h ik l m n o p q r s t u v w x y z a b c d e f g h i jl m n o p q r s t u v w x y z a b c d e f g h i j k

m n o p q r s t u v w x y z a b c d e f g h i j k ln o p q r s t u v w x y z a b c d e f g h i j k l mo p q r s t u v w x y z a b c d e f g h i j k l m np q r s t u v w x y z a b c d e f g h i j k l m n oq r s t u v w x y z a b c d e f g h i j k l m n o pr s t u v w x y z a b c d e f g h i j k l m n o p qs t u v w x y z a b c d e f g h i j k l m n o p q rt u v w x y z a b c d e f g h i j k l m n o p q r su v w x y z a b c d e f g h i j k l m n o p q r s tv w x y z a b c d e f g h i j k l m n o p q r s t uw x y z a b c d e f g h i j k l m n o p q r s t u vx y z a b c d e f g h i j k l m n o p q r s t u v wy z a b c d e f g h i j k l m n o p q r s t u v w xz 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

• aka Le Chiffre Indechriffrable

• Polyalphabetic cipher

• Alternate alphabets by key - so using a key of Drupal would mean alternating between rows 4/18/21/16/1/12 for each encrypted character

• Removes correlation between character frequencies, defeating frequency analysis attack

CRYPTANALYST AND SHIZZ

ENTER BABBAGE

https://www.flickr.com/photos/stubot/17902445998/in/album-72157650729143213/https://creativecommons.org/licenses/by-nc-sa/2.0/

CRYPTANALYST AND SHIZZ

ENTER BABBAGE

• Invented method of cracking Vigenere cipher in response to John Hall Brock Thwaites

• Method involved looking for multiple repeated patterns, taking common factors and deducing the length of the key

• Then treat as n separate frequency analyses

• Work not published - due to the Crimean War?

INTO THE 20TH CENTURY

DRIVERS OF CRYPTOGRAPHY

• Technology

• Telegraph

• Wireless

• Literature

• The Gold Bug by Edgar Allen Poe

• The Adventure of the Dancing Men by Arthur Conan Doyle

• Illicit personals in the newspapers

https://en.wikipedia.org/wiki/The_Adventure_of_the_Dancing_Men#/media/File:Dancing_men.svg

CRYPTOGRAPHY AND CRYPTANALYSIS

WAR! WHAT IS IT GOOD FOR?

• World War I

• French pulled up the landlines

• German ADFGVX cipher, broken by Georges Painvin

• More variations on 19th century ciphers

• Germany late to the party

HIDING YOUR HAND

WAR! WHAT IS IT GOOD FOR?

• The Zimmerman Telegram

• Germany proposed military alliance with Mexico

• Encrypted but broken by the British

• Had to also steal the decrypted version

• Hastened America's entry in to the war

MECHANISED ENCRYPTION

ENTER THE ENIGMA MACHINE

https://en.wikipedia.org/wiki/Enigma_machine#/media/File:Enigma_(crittografia)_-_Museo_scienza_e_tecnologia_Milano.jpg

MECHANISED ENCRYPTION

ENTER THE ENIGMA MACHINE

• Used commercially from about 1925

• More complicated versions for the military

• Plans acquired by the French who ignored them

• Shared by agreement with Poland who were far more nervous and cracked the initial version

• When the encryption increased, all research handed over to the British

BLETCHLEY PARK CREW

ENTER THE ENIGMA MACHINE

• Daily code repeated

• Seeding

• Stealing code books from submarines

• Reckoned to have shortened the war by 3 years

• Work not disclosed until 1974

DIFFIE & HELLMAN & MERKLE

SOLVING KEY DISTRIBUTION

• Inspired by the Arpanet

• First proved a synchronous form of key exchange

• Developed asymmetric key concept

• Working algorithm developed by Rivest, Shamir & Adleman in 1977. RSA.

• Independently invented in GCHQ in half an afternoon by Cocks building on others' work 4 years earlier but not disclosed until 1994

PHIL ZIMMERMAN

PRETTY GOOD PRIVACY

• Built on RSA but brought it to the masses

• Freeware, but not initially

• Released 1991 and immediately used in conflict zones

• Kicked off a debate that's still going today

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FURTHER READING

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THE CODE BOOKSimon SinghISBN: 978-1-85702-879-9