The modern computer was born from Polish, British and American efforts to decode secret German and Japanese messages during the Second World War. The complex processes instantiated in these cryptographic machines are excellent examples of early hand, mechanical, electromechanical and electronic computing devices, spanning technologies from the relatively simple slide-rule, disk and cylinder mechanisms, to complex clockwork devices with gears and levers, and to the rotor machines that featured so prominently in the advances in decryption and computation developed at Bletchley Park.

1777 Aspinwall Revolutionary War Cipher
A cipher regarding international trade.

17th Century Silver disk by Nicolas Bion
Instrument maker to King Louis XIV.


KRIPTO System Beyer
A periodic disk cipher in a pocket watch case.

The Cook Cryptograph
A mechanical version of an electrical ciphering device by the American Brake Shoe Company.
Key Guns  For inserting keys into cryptographic machines.

Bletchley Park Enigma Event 2009

Exhibits and exhibitors...

National Cryptologic Museum
For inserting keys into cryptographic machines.

The Hebern Code Machine

The first patented electromechanical rotor machine.

Soviet Machines
The FIALKA, an improved 10-rotor version of the German Enigma.

Swiss NEMA
An improved version of the German Enigma.


Microchips before the microcomputer.

One-Time-Tape Devices
Absolutely secure if the tape is random and protected.

Hagelin Machines
Mechanical marvels.


The heart of the maze which scrambles alphabets.

Disk & Strip Ciphers
Early changeable monoalphabetic substitution devices.

Random Key Generators
Random and pseudo-random key generators.

Underwood Code Machine
RIP-5. One of only nine built in 1925 for the
US Navy to transcribe intercepted Japanese messages.

Polyalphabetic Ciphers

Complex mechanical polyalphabetic substitution devices.

Burst Encoders
Getting the message out so quickly that no one notices.

Paper Alphabets
Relatively simple hand-coded algorithms.

Code Tables

Still in use...

Silk Covert One-Time-Pads
Intended to be hidden, used once, and then destroyed...

Frank Byron Rowlett Papers

Signed and initialed cryptanalytic course materials.

Cryptanalysis with Hollerith Cards
Predecessors of KWIC and KWOC using IBM punch card handling equipment.

Encrypted Post-Cards & Letters
For business, romance and children.

Code Books
For military or business by telegraphy.

Toys & Related Items

For nostalgic and entertainment purposes.

Demonstrations of some basic principles.

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