Definitions

cast

cast iron

Alloy of iron that contains 2–4percnt carbon, along with silicon, manganese, and impurities. It is made by reducing iron ore in a blast furnace (cast iron is chemically the same as blast-furnace iron) and casting the liquid iron into ingots called pigs. Pig iron is remelted, along with scrap and alloying elements, in cupola furnaces and recast into molds for a variety of products. In the 18th–19th centuries, cast iron was a cheaper engineering material than wrought iron (not requiring intensive refining and hammering). It is more brittle and lacks tensile strength. Its compressive (load-bearing) strength made it the first important structural metal. In the 20th century, steel replaced it as a construction material, but cast iron still has industrial applications in automobile engine blocks, agricultural and machine parts, pipes, hollowware, stoves, and furnaces. Most cast iron is either so-called gray iron or white iron, the colours shown by fracture; gray iron contains more silicon and is less hard and more machinable than white iron. Both are brittle, but malleable cast iron (produced by prolonged heat-treating), first made in 18th-century France, was developed into an industrial product in the U.S. Cast iron that is ductile as cast was invented in 1948. The latter now constitutes a major family of metals, widely used for gears, dies, automobile crankshafts, and many other machine parts.

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The following article is about the block cipher. For the axion observatory in Switzerland, see CERN Axion Solar Telescope.
In cryptography, CAST-128 (alternatively CAST5) is a block cipher used in a number of products, notably as the default cipher in some versions of GPG and PGP. It has also been approved for Canadian government use by the Communications Security Establishment. The algorithm was created in 1996 by Carlisle Adams and Stafford Tavares using the CAST design procedure; another member of the CAST family of ciphers, CAST-256 (a former AES candidate) was derived from CAST-128. According to some sources, the "CAST" name is based on the initials of its inventors, though Bruce Schneier reports the authors' claim that "the name should conjure up images of randomness" (Schneier, 1996).

CAST-128 is a 12- or 16-round Feistel network with a 64-bit block size and a key size of between 40 to 128 bits (but only in 8-bit increments). The full 16 rounds are used when the key size is longer than 80 bits. Components include large 8×32-bit S-boxes based on bent functions, key-dependent rotations, modular addition and subtraction, and XOR operations. There are three alternating types of round function, but they are similar in structure and differ only in the choice of the exact operation (addition, subtraction or XOR) at various points.

Although Entrust holds a patent on the CAST design procedure, CAST-128 is available worldwide on a royalty-free basis for commercial and non-commercial uses.

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