327 results about "Key size" patented technology

In cryptography, key size or key length is the number of bits in a key used by a cryptographic algorithm (such as a cipher). Key length 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 key length), since the security of all algorithms can be violated by brute-force attacks. Ideally, key length 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 key, 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 key length and security is sufficient for a particular application, then it doesn't matter if key length 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 key length.