A Brief History of Secret Writing
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Transcript of A Brief History of Secret Writing
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A BRIEF HISTORY OF SECRET WRITING
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Secret Writing
(hidden writing) (obfuscated writing)Steganography Cryptography
A Brief History of
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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
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EXAMPLES OF HIDDEN WRITING
STEGANOGRAPHY
Weird Chinese thing• Write message on silk • Ball up silk, and coat in wax • Eat ball • ??????????????????? • Profit
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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
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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
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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
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HIDING THE MEANING OF A MESSAGE
CRYPTOGRAPHY
Secret Writing
CryptographySteganography
Transposition Substitution
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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
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SCYTALE
TRANSPOSITION CIPHERS
Lysander of Sparta vs Pharnabazus of Persia, 5th century BCE
https://en.wikipedia.org/wiki/File:Skytale.png
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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
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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
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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
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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
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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
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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
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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
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MARY QUEEN OF SCOTS
THE BABINGTON PLOT
http
s://e
n.wi
kiped
ia.or
g/wi
ki/Ba
bing
ton_
Plot
#/m
edia/
File:
Mar
y-cip
her-c
ode.
jpg
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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
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CRYPTANALYST AND SHIZZ
ENTER BABBAGE
https://www.flickr.com/photos/stubot/17902445998/in/album-72157650729143213/https://creativecommons.org/licenses/by-nc-sa/2.0/
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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?
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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
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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
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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
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MECHANISED ENCRYPTION
ENTER THE ENIGMA MACHINE
https://en.wikipedia.org/wiki/Enigma_machine#/media/File:Enigma_(crittografia)_-_Museo_scienza_e_tecnologia_Milano.jpg
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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
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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
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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
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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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BUY THIS BOOK
FURTHER READING
BUY ALL HIS BOOKS
THE CODE BOOKSimon SinghISBN: 978-1-85702-879-9