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
20
th
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
Cost
Cost
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
Navy
–
4 wheel
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/
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