!!! Overview
[{$pagename}] in [Cryptography] or key length is the number of [bits] in a [key] used by a [Cryptographic Primitive] (such as a [cipher] or [Hash Function]).

[{$pagename}] defines the upper-bound on an [algorithm]'s security (i.e., a logarithmic measure of the fastest known [attack] against an [algorithm], relative to the [{$pagename}]), since the security of all [algorithms] can be violated by [Brute-Force] [attacks]. 


Ideally, [{$pagename}] would coincide with the lower-bound on an algorithm's security. Indeed, most [Symmetric Key] algorithms are designed to have security equal to their key length. 


However, after design, a new attack might be discovered. For instance, [Triple DES] was designed to have a 168 [bit] [{$pagename}], but an [attack] of complexity 2112 is now known (i.e., [Triple DES] has 112 [bits] of security). Nevertheless, as long as the relation between [{$pagename}] and security is sufficient for a particular application, then it doesn't matter if [{$pagename}] and security coincide. This is important for [Asymmetric Key] [algorithms], because no such algorithm is known to satisfy this property; [Elliptic Curve] [cryptography] comes the closest with an effective security of roughly half its [{$pagename}].


[Hash Function Security|Hash Function Security Properties] has some details in regards to [{$pagename}]

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