Editing Kerckhoffs's principle (section)

{{short description|Cryptographic principle that states everything except the key can be public knowledge}}
{{Distinguish|Kirchhoff's laws (disambiguation){{!}}Kirchhoff's laws}}

[[File:Auguste_Kerckhoffs.jpg|thumb|Auguste Kerckhoffs]]
'''Kerckhoffs's principle''' (also called '''Kerckhoffs's desideratum''', '''assumption''', '''axiom''', '''doctrine''' or '''law''') of [[cryptography]] was stated by [[Dutch people|Dutch-born]] cryptographer [[Auguste Kerckhoffs]] in the 19th century. The principle holds that a [[cryptosystem]] should be secure, even if everything about the system, except the [[cryptographic key|key]], is public knowledge. This concept is widely embraced by cryptographers, in contrast to [[security through obscurity]], which is not.

Kerckhoffs's principle was phrased by American mathematician [[Claude E. Shannon|Claude Shannon]] as "the [[Adversary (cryptography)|enemy]] knows the system",<ref name=Shannon>{{cite journal|last1=Shannon|first1=Claude|title=Communication Theory of Secrecy Systems|journal=Bell System Technical Journal|date=4 October 1949|volume=28|issue=4|page=662|doi=10.1002/j.1538-7305.1949.tb00928.x|url=https://archive.org/stream/bstj28-4-656#page/n5/mode/2up|access-date=20 June 2014|ref=Shannon}}</ref> i.e., "one ought to design systems under the assumption that the enemy will immediately gain full familiarity with them".  In that form, it is called '''Shannon's maxim'''.

Another formulation by American researcher and professor [[Steven M. Bellovin]] is:
<blockquote>In other words—design your system assuming that your opponents know it in detail. (A former official at NSA's National Computer Security Center told me that the standard assumption there was that serial number 1 of any new device was delivered to the Kremlin.)<ref name="Bellovin">{{cite journal|last1=Bellovin|first1=Steve|title=Security through obscurity|journal=RISKS Digest|date=23 June 2009|volume=25|issue=71|url=http://catless.ncl.ac.uk/Risks/25.71.html#subj19|access-date=18 September 2010|archive-date=10 June 2011|archive-url=https://web.archive.org/web/20110610065131/http://catless.ncl.ac.uk/Risks/25.71.html#subj19|url-status=live}}</ref></blockquote>