cryptography, an algorithm's key space refers to the set of all possible keys that can be used to initialize it. For example, if an algorithm works using a key that is a string of 10 bits, then its key space is the set of all binary strings of length 10.
To avoid adversaries from guessing the key using a
brute-force attack, the key space is usually designed to be extremely large. Another desirable attribute is that the key space be "flat", having no or very few weak keys.
block cipherRijndael/AES uses a key of up to 256 bits, resulting in a key space containing over 1.1579 × 1077 keys. This makes it computationally infeasible to check each possible key by brute force.
ROT13cipher is only intended to prevent people from accidentally reading messages (e.g. movie plot details). As there is no key, the key space is therefore empty.
Wikimedia Foundation. 2010.
Look at other dictionaries:
space key — space bar space bar or space key space key (Mach., Computers) A bar or key, in a typewriter, typesetting machine, or other keyboard (as a computer keyboard), used to insert a space between letters. [Webster 1913 Suppl. +PJC] … The Collaborative International Dictionary of English
space bar — or space key space key (Mach., Computers) A bar or key, in a typewriter, typesetting machine, or other keyboard (as a computer keyboard), used to insert a space between letters. [Webster 1913 Suppl. +PJC] … The Collaborative International Dictionary of English
Space.com — Infobox Website name = Space.com caption = Space.com in October 2006 url = http://www.space.com commercial = no type = News, astronomy language = English registration = Not required owner = Imaginova author = Lou Dobbs and Rich Zahradnik launch… … Wikipedia
Space Family Robinson — was an original science fiction comic book series published by Gold Key Comics. It predates the Lost in Space TV series, and was a possible inspiration for it. Gold Key later incorporated Lost in Space into the comic s title as a weak tie in to… … Wikipedia
Space Taxi — is a computer game for the Commodore 64. It was written by John Kutcher and published by MUSE Software in 1984. Space Taxi is an action game, with an idea similar to Jumpman . There are 24 different levels, all in sequential order, and the player … Wikipedia
Space exploration — is the use of astronomy and space technology to explore outer space. [cite web | url = http://adc.gsfc.nasa.gov/adc/education/space ex/exploration.html | title = How Space is Explored | publisher = NASA] Physical exploration of space is conducted … Wikipedia
Key hole — Key Hole, trou de serrure en français, est le nom de code de certains satellites espions américains successeurs du programme Corona. Il y en a actuellement officieusement quatre en orbite héliosynchrone. Ils sont désignés sous les sigles KH 11 et … Wikipédia en Français
Space exposure — is in reference to the exposure of a human to the conditions of outer space, without protective clothing and beyond the Earth’s atmosphere in a vacuum.Explanation and history of space exposureThe key concerns for a human without protective… … Wikipedia
Space stations and habitats in popular culture — Space stations and habitats are an important element in popular culture.Space stations are smaller structures where people usually stay for limited periods.A space habitat, also called space colony, orbital colony, space city, or space settlement … Wikipedia
key — key1 [kē] n. pl. keys [ME keye < OE cæge, akin to OFris kei, kēia, to secure, guard] 1. an instrument, usually of metal, for moving the bolt of a lock and thus locking or unlocking something 2. any of several instruments or mechanical devices… … English World dictionary