Editing Block cipher (section)

==Practical evaluation==
Block ciphers may be evaluated according to multiple criteria in practice. Common factors include:{{sfn|Menezes|van Oorschot|Vanstone|1996|p=227}}<ref name="AESr2report">{{citation|author1=James Nechvatal |author2=Elaine Barker |author3=Lawrence Bassham |author4=William Burr |author5=Morris Dworkin |author6=James Foti |author7=Edward Roback |title=Report on the Development of the Advanced Encryption Standard (AES)|publisher=National Institute of Standards and Technology (NIST)|date=October 2000|url=http://csrc.nist.gov/archive/aes/round2/r2report.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://csrc.nist.gov/archive/aes/round2/r2report.pdf |archive-date=2022-10-09 |url-status=live}}</ref>
* Key parameters, such as its key size and block size, both of which provide an upper bound on the security of the cipher.
* The ''estimated security level'', which is based on the confidence gained in the block cipher design after it has largely withstood major efforts in cryptanalysis over time, the design's mathematical soundness, and the existence of practical or certificational<ref>Attacks that show that the cipher does not perform as advertised (i.e., the level of difficulty involved in breaking it is lower than claimed), which are nevertheless of high enough complexity so that they are not practically achievable.</ref> attacks.
* The cipher's ''complexity'' and its suitability for implementation in [[electronic hardware|hardware]] or [[software]]. Hardware implementations may measure the complexity in terms of [[gate count]] or energy consumption, which are important parameters for resource-constrained devices.
* The cipher's ''performance'' in terms of processing [[throughput]] on various platforms, including its [[computer memory|memory]] requirements.
* The ''cost'' of the cipher refers to licensing requirements that may apply due to [[intellectual property right]]s.
* The ''flexibility'' of the cipher includes its ability to support multiple key sizes and block lengths.