Encryption is one of the most important parts of modern application security. But the practice of obfuscating messages go far further back in history than many realise. In this talk we'll take a look at the development ; the differences between steganography and cryptography, between codes and ciphers, and the unceasing battle between cryptographers and cryptanalysts throughout history and the very human stories behind it.

1. A BRIEF HISTORY OF
SECRET WRITING

2. Secret Writing
(hidden writing) (obfuscated writing)
Steganography Cryptography
A Brief History of

3. 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

4. EXAMPLES OF HIDDEN WRITING
STEGANOGRAPHY
Weird Chinese thing
• Write message on silk
• Ball up silk, and coat in wax
• Eat ball
• ???????????????????
• Profit

5. 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

6. 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

7. 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

8. HIDING THE MEANING OF A MESSAGE
CRYPTOGRAPHY
Secret Writing
CryptographySteganography
Transposition Substitution

9. 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

10. SCYTALE
TRANSPOSITION CIPHERS
Lysander of Sparta vs Pharnabazus of Persia, 5th century BCE
https://en.wikipedia.org/wiki/File:Skytale.png

11. 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 z
w 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
plaintext
ciphertext
JMVWX MQ SR XLI SYXWMHI EW MQ PSSOMRK EX XLI GIRXVI
ILUVW LP RQ WKH RXWVLGH DV LP ORRNLQJ DW WKH FHQWUHKey -1
HKTUV KO QP VJG QWVUKFG CU KO NQQMKPI CV VJG EGPVTGKey -2
GJSTU JN PO UIF PVUTJEF BT JN MPPLJOH BU UIF DFOUSFKey -3
FIRST IM ON THE OUTSIDE AS IM LOOKING AT THE CENTREKey -4
Caesar cipher is limited to 25 keys

12. SIMPLE SUBSTITUTION CIPHERS - INCREASE THE KEYS
SUBSTITUTION CIPHER
Generate far more potential keys by pairing letters in random order
plaintext
ciphertext
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
h
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

13. SIMPLE SUBSTITUTION CIPHERS - MEMORABLE KEYS
SUBSTITUTION CIPHER
plaintext
ciphertext
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
n
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

14. ENTER THE ARABS
V
Frequency Analysis
53‡‡†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

15. ENTER THE ARABS
CRYPTANALYSIS VS CRYPTOGRAPHY
Frequency Analysis
53‡‡†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

16. 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
SCOTLAND
HENRY VIII
FIRST COUSINS ONCE
REMOVED

17. 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

18. MARY QUEEN OF SCOTS
THE BABINGTON PLOT
https://en.wikipedia.org/wiki/Babington_Plot#/
media/File:Mary-cipher-code.jpg

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

20. CRYPTANALYST AND SHIZZ
ENTER BABBAGE
https://www.flickr.com/photos/stubot/17902445998/in/album-72157650729143213/
https://creativecommons.org/licenses/by-nc-sa/2.0/

21. 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?

22. 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

23. 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

24. 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

25. MECHANISED ENCRYPTION
ENTER THE ENIGMA MACHINE
https://en.wikipedia.org/wiki/Enigma_machine#/media/File:Enigma_(crittografia)_-
_Museo_scienza_e_tecnologia_Milano.jpg

26. 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

27. 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

28. 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

29. 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

30. BUY THIS BOOK
FURTHER READING
BUY ALL HIS BOOKS
THE CODE BOOK
Simon Singh
ISBN: 978-1-85702-879-9