More complex (and hopefully more effective) encryption is possible with the aid of machines: dedicated mechanical and electromechanical devices, mechanical, electronic (and fluidic) calculators; and programmed electronic (and fluidic) computers.

Mechanical Crypto Machines

Prior to the advent of the digital computer, machines were built that could encipher or decipher messages according to rules too complicated to be carried out by hand with sufficient speed and accuracy.

Of these, my favorite is the Jefferson wheel . . .

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- The Grantville Gazette Staff