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Collections in Cryptology - Key Generators
Key mechanisms in computation...

Cold War German Pseudo-Random Key Generator
Truly a Rube Goldbergian device, it was abandoned after it proved to be too complicated to use in the field. There are 26 slides available, each with four sides. Ten of these were placed in the device in a predetermined order, each with one of its four sides showing and in a unique horizontal position. The cursor contained a removable grille which was slid to a predetmined position. The pseudo-random key was read down each column of the cursor, moving to the next column, and when the columns were exhausted the device was turned over and the cursor on the opposite side was read in the same manner. When the columns on the opposite side were exhausted the device was turned over once again and the cursor advanced to the right one position. This was continued until the proper key length was reached.