Hard

Hard or hardness may refer to:

Entertainment

See also

Hard (Zürich)

Hard is a quarter in the district 4 of Zürich.

It was formerly a part of Aussersihl municipality, which was incorporated into Zürich in 1893.

The quarter has a population of 12,715 distributed on an area of 1.46 km².

Coordinates: 47°22′46.59″N 8°30′57.64″E / 47.3796083°N 8.5160111°E / 47.3796083; 8.5160111

Hard (surname)

Hard is a surname. Notable people with the surname include:

Sturgeon (surname)

Sturgeon is a surname. Notable people with the surname include:

Sturgeon (disambiguation)

Sturgeon is the common name for many species of fish.

Sturgeon may also refer to:

Places

Military uses

Siemens and Halske T52

The Siemens & Halske T52, also known as the Geheimfernschreiber ("secret teleprinter"), or Schlüsselfernschreibmaschine (SFM), was a World War II German cipher machine and teleprinter produced by the electrical engineering firm Siemens & Halske. The instrument and its traffic were codenamed Sturgeon by British cryptanalysts.

While the Enigma machine was generally used by field units, the T52 was an online machine used by Luftwaffe and German Navy units, which could support the heavy machine, teletypewriter and attendant fixed circuits. It fulfilled a similar role to the Lorenz cipher machines in the German Army.

The British cryptanalysts of Bletchley Park codenamed the German teleprinter ciphers Fish, with individual cipher-systems being given further codenames: just as the T52 was called Sturgeon, the Lorenz machine was codenamed Tunny.

Operation

The teleprinters of the day emitted each character as five parallel bits on five lines, typically encoded in the Baudot code or something similar. The T52 had ten pinwheels, which were stepped in a complex nonlinear way, based in later models on their positions from various delays in the past, but in such a way that they could never stall. Each of the five plaintext bits was then XORed with the XOR sum of 3 taps from the pinwheels, and then cyclically adjacent pairs of plaintext bits were swapped or not, according to XOR sums of three (different) output bits. The numbers of pins on all the wheels were coprime, and the triplets of bits that controlled each XOR or swap were selectable through a plugboard.