In cryptography, **key size** or **key length** is the size measured in bits of the key used in a cryptographic algorithm (such as a cipher). An algorithm's key length is distinct from its cryptographic security, which is a logarithmic measure of the fastest known computational attack on the algorithm, also measured in bits. The security of an algorithm cannot exceed its key length (since any algorithm can be cracked by brute force), but it can be smaller. For example, Triple DES has a key size of 168 bits but provides at most 112 bits of security, since an attack of complexity 2112 is known. This property of Triple DES is not a weakness provided 112 bits of security is sufficient for an application. Most symmetric-key algorithms in common use are designed to have security equal to their key length. No asymmetric-key algorithms with this property are known; elliptic curve cryptography comes the closest with an effective security of roughly half its key length.

Read more about Key Size: Significance, Key Size and Encryption System, Brute Force Attack, Symmetric Algorithm Key Lengths, Asymmetric Algorithm Key Lengths, Effect of Quantum Computing Attacks On Key Strength

### Other articles related to "key size, keys, key":

**Key Size**

... The

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**keys**... Thus or about is an upper bound on the

**key size**of the Hill cipher using n × n matrices ... This is only an upper bound because not every matrix is invertible and thus usable as a

**key**...

... of columns, for example seven QPWKALV RXCQZIK GRBPFAE OMFLJMS DZVDHXC XJYEBIM TRQWN… If the

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**key size**(number of columns), the aggregate delta I.C ...

... complexity of a brute force attack using a technique called

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**key size**256 possibilities for the

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**Key Size**- Effect of Quantum Computing Attacks On Key Strength

... widely conjectured to be effective against all mainstream public-

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**key**algorithms are insecure at any

**key size**if sufficiently large quantum computers capable of running Shor's algorithm become ... Encrypted data protected using public-

**key**algorithms can be archived and may be broken at a later time ...

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—Alex Atkinson, British humor writer. repr. In Present Laughter, ed. Alan Coren (1982)

“The *key* word in my plays is “perhaps.””

—Samuel Beckett (1906–1989)