Pinwheel (cryptography)

The German Lorenz cipher machine contained 12 pinwheels, with a total of 501 pins

In cryptography, a pinwheel was a device for producing a short pseudorandom sequence of bits (determined by the machine's initial settings), as a component in a cipher machine. A pinwheel consisted of a rotating wheel with a certain number of positions on its periphery. Each position had a "pin", "cam" or "lug" which could be either "set" or "unset". As the wheel rotated, each of these pins would in turn affect other parts of the machine, producing a series of "on" or "off" pulses which would repeat after one full rotation of the wheel. If the machine contained more than one wheel, usually their periods would be relatively prime to maximize the combined period.

Pinwheels might be turned through a purely mechanical action (as in the M-209) or electromechanically (as in the Lorenz SZ 40/42). Other cipher machines which used pinwheels include the C-52, the CD-57 and the Siemens and Halske T52.

Pinwheels can be viewed as a predecessor to the electronic linear feedback shift register (LFSR), used in later cryptosystems.

See also

• Rotor machine

Cipher machines Rotor machines CCM Enigma M-125 Fialka Hebern HX-63 KL-7 Lacida M-325 Mercury NEMA OMI Portex RED SIGABA SIGCUM Singlet Typex Mechanical Bazeries cylinder C-36 C-52 CD-57 Cipher disk HC-9 Kryha Jefferson disk M-94 M-209 Reihenschieber Scytale Teleprinter 5-UCO BID 770 DUDEK KW-26 KW-37 Lorenz SZ 40/42 Siemens and Halske T52 Secure voice BID 150 FASCINATOR KY-3 KY-57 KY-58 KY-68 NESTOR OMNI SCIP Sectéra Secure Module SIGSALY STE STU-II STU-III VINSON Other JADE KG-84 KL-43 KL-51 Noreen PURPLE GREEN（Japanese：-{グリーン暗号}-） Pinwheel Rockex Cryptography History of cryptography Cryptanalysis Outline of cryptography Symmetric-key algorithm Block cipher Stream cipher Public-key cryptography Cryptographic hash function Message authentication code Random numbers Steganography Portal