tiger

Tigers are famous for their orange (or more rarely, white) coats with black stripes, a camouflage pattern that helps them blend into tall grass or forests. They are solitary hunters who ambush their prey from about 30 feet away, leaping in to bite the throat or back of the neck. They like to swim, unlike many felines, and will chase prey into the water. Once they've killed, they will drag the carcass into seclusion to eat.

There were eight subspecies of tiger; three are now extinct, but the other five roam throughout much of Asia. Tigers in general are endangered because their habitat is being built over, especially in India, because they are hunted for their fur and their bones (which are ground into a supposed aphrodisiac) and because they will kill livestock and people if they have no other food. There may be only about 6,000 left in the wild.

The Tiger hash function was invented by Eli Biham and Ross Anderson. It is significantly different in internal structure from most other hash functions in use (such as MD5 and SHA-1), making use of multiplications and substitution boxes rather than lots of interleaved additions and bit-logical operations, which is the method used by most other hash functions.

It produces a 192-bit output, and internally uses 64-bit integer arithmetic. The multiplications are done against constant values: 5, 7, and 9 (the DEC (see also Compaq) Alpha has special instructions for these multiplications, which was why those specific values were chosen). The mutiplications are used to spread out the bits; a single bit change in the input will affect many of the bits of the output (the term for this is high diffusion).

So far, there are no known attacks, but nobody is using it much either (in that sense it is pretty similiar to the HAVAL hash function). The only place it is being used in (to my knowledge) is in the IETF OpenPGP standard as an optional algorithm; GnuPG actually implements it.

It seems Biham and Anderson like using animal names for cryptographic primitives: they have worked on Tiger, Serpent (with Lars Knudsen), Lion, Bear, Lioness, and Chameleon.

Ti"ger (?), n. [OE. tigre, F. tigre, L. tigris, Gr. ti`gris; probably of Persian origin; cf. Zend tighra pointed, tighri an arrow, Per. tir; perhaps akin to E. stick, v.t.; -- probably so named from its quickness.]

1.

A very large and powerful carnivore (Felis tigris) native of Southern Asia and the East Indies. Its back and sides are tawny or rufous yellow, transversely striped with black, the tail is ringed with black, the throat and belly are nearly white. When full grown, it equals or exceeds the lion in size and strength. Called also royal tiger, and Bengal tiger.

2.

Fig.: A ferocious, bloodthirsty person.

As for heinous tiger, Tamora. Shak.

3.

A servant in livery, who rids with his master or mistress.

Dickens.

4.

A kind of growl or screech, after cheering; as, three cheers and a tiger.

5.

A pneumatic box or pan used in refining sugar.

American tiger. Zool. (a) The puma. (b) The jaguar. -- Clouded tiger Zool., a handsome striped and spotted carnivore (Felis macrocelis or F. marmorata) native of the East Indies and Southern Asia. Its body is about three and a half feet long, and its tail about three feet long. Its ground color is brownish gray, and the dark markings are irregular stripes, spots, and rings, but there are always two dark bands on the face, one extending back from the eye, and one from the angle of the mouth. Called also tortoise-shell tiger. -- Mexican tiger Zool., the jaguar. -- Tiger beetle Zool., any one of numerous species of active carnivorous beetles of the family Cicindelidae. They usually inhabit dry or sandy places, and fly rapidly. -- Tiger bittern. Zool. See Sun bittern, under Sun. -- Tiger cat Zool., any one of several species of wild cats of moderate size with dark transverse bars or stripes somewhat resembling those of the tiger. -- Tiger flower Bot., an iridaceous plant of the genus Tigridia (as T. conchiflora, T. grandiflora, etc.) having showy flowers, spotted or streaked somewhat like the skin of a tiger. -- Tiger grass Bot., a low East Indian fan palm (Chamaerops Ritchieana). It is used in many ways by the natives. J. Smith (Dict. Econ. Plants). -- Tiger lily. Bot. See under Lily. -- Tiger moth Zool., any one of numerous species of moths of the family Arctiadae which are striped or barred with black and white or with other conspicuous colors. The larvae are called woolly bears. -- Tiger shark Zool., a voracious shark (Galeocerdo maculatus or tigrinus) more or less barred or spotted with yellow. It is found in both the Atlantic and Indian Ocean. Called also zebra shark. -- Tiger shell Zool., a large and conspicuously spotted cowrie (Cypraea tigris); -- so called from its fancied resemblance to a tiger in color and markings. Called also tiger cowrie. -- Tiger wolf Zool., the spotted hyena (Hyaena crocuta). -- Tiger wood, the variegated heartwood of a tree (Machaerium Schomburgkii) found in Guiana.

© Webster 1913.