Key clustering: Difference between revisions

Revision as of 15:42, 19 February 2009

Revision as of 22:20, 18 August 2009

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{{Orphan|date=February 2009}}

{{Expert-subject|Cryptography|date=February 2009}}

In [[cryptography]], '''key clustering''' is said to occur when two different [[key (cryptography)|keys]] generate the same [[ciphertext]] from the same [[plaintext]], using the same [[cipher]] [[algorithm]]. A good cipher algorithm, using different keys on the same plaintext, should generate a different ciphertext, irrespective of the key length.

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If an 'attacker' tries to break a cipher by [[brute-force]] (trying all possible keys until it finds the correct key) then key clustering will result in an easier attack on a particular cipher text. If there are N possible keys with out any key clustering then the attacker will on average need to try N/2 keys to decrypt it and a worst case of trying all N keys. If there are two keys that are clustered then the average number of keys to try is reduced to N/4 (worst case is N-1 keys). If three keys cluster than average attempt is only N/6 attempts.

==References==

{{reflist}}

==External links==

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[[Category:Key management]]

{{crypto-stub}}