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Mechanising Cryptography
Professor Richard Walton CB
Cryptography is concerned with
the application of technology to
the problem of encrypting and
decrypting a message.
The Mathematics is
subordinate to the technology
20th Century Cryptography
 Development of Crypt in the 1900s
 Manual Methods
– Slow
– Laborious
– Error-Prone
 Need to mechanise
 Importance of technology for design
 Nature of technological constraints
CRYPTOGRAPHY
Security
Usability
Cost
Cryptanalysis 1918
 Knowledge of language
 Frequency Analysis
 Key Re-use (Depth)
Skill Requirement:
To solve crossword puzzles
in foreign languages
Rotor Machines
Rotors
Commercial Enigma
Enigma
Enigma
Army
Navy – 4 wheel
Navy
Early Machine Cryptography
 Limitations of Security Design
 Balance Security against Cost
 Usability – Human Factors
Electronics – 1960-1980
 Shift Registers and Simple Logic Gates
 Linear Algebra
 Galois Theory
 Rich Mathematical structure
 Rigorous Analysis
 Expensive Components
Large Scale Integration
 Application Specific Integrated Circuits
 Complex Algorithms
 Tailored to purpose
 Standard Cryptographic Primitives
 Software and Firmware
Public Key Cryptography
 Key Management
 Non-Secret Encryption
– Ellis, Cocks & Williamson
– Beyond 1970’s technology
 Widespread after 1985
 Search for easier solutions
– Elliptic Curve Cryptography
Next Challenge
Quantum Computers destroy
current Public Key algorithms
Find new algorithms to resist
Quantum Computer attacks
Mechanising Cryptography
Acknowledgement
Illustrations concerning Enigma in this presentation
have been taken from the user manual for Enigma – E
by Paul Reuvers & Marc Simons.
For details of Enigma-E, which is available for purchase
from Bletchley Park Museum, see www.xat.nl/enigma-e/