Editing Communication Theory of Secrecy Systems

{{Short description|1949 paper by Claude Shannon}}
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| author            = [[Claude E. Shannon]]
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| subject           = [[Cryptography]]
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| pub_date          = 1949
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'''"Communication Theory of Secrecy Systems"''' is a paper published in 1949 by [[Claude Shannon]] discussing [[cryptography]] from the viewpoint of [[information theory]].<ref>Shannon, "Communication Theory of Secrecy Systems," p. 656. [http://www.prism.net/user/dcowley/shannon/shannon01.jpg]</ref> It is one of the foundational treatments (arguably ''the'' foundational treatment) of modern cryptography.<ref>{{Cite book |last1=Shimeall |first1=Timothy J. |url=https://books.google.com/books?id=eZBqAAAAQBAJ&pg=PA167 |title=Introduction to Information Security: A Strategic-Based Approach |last2=Spring |first2=Jonathan M. |publisher=Syngress |year=2013 |isbn=978-1597499699 |pages=167 |language=en}}</ref> His work has been described as a "turning point, and marked the closure of classical cryptography and the beginning of modern cryptography."<ref>{{Cite journal |last1=Koç |first1=Çetin Kaya |last2=Özdemir |first2=Funda |date=2023 |title=Development of Cryptography since Shannon |url=https://cetinkayakoc.net/publications.html |journal=Handbook of Formal Analysis and Verification in Cryptography|pages=1–56 |doi=10.1201/9781003090052-1 |isbn=978-1-003-09005-2 |url-access=subscription }}</ref> It has also been described as turning cryptography from an "art to a science".<ref>{{Cite book |last=Zheng |first=Zhiyong |url=https://books.google.com/books?id=dG1rEAAAQBAJ&pg=PR6 |title=Modern Cryptography Volume 1: A Classical Introduction to Informational and Mathematical Principle |date=2022 |publisher=Springer Singapore |isbn=978-981-19-0919-1 |series=Financial Mathematics and Fintech |location=Singapore |pages=vi |language=en |doi=10.1007/978-981-19-0920-7}}</ref> It is also a proof that all theoretically unbreakable ciphers must have the same requirements as the [[one-time pad]]. 

The paper serves as the foundation of [[Symmetric-key algorithm|secret-key cryptography]], including the work of [[Horst Feistel]], the [[Data Encryption Standard|Data Encryption Standard (DES)]], [[Advanced Encryption Standard|Advanced Encryption Standard (AES)]], and more.<ref name=":9">{{Cite journal |last1=Koç |first1=Çetin Kaya |last2=Özdemir |first2=Funda |date=2023 |title=Development of Cryptography since Shannon |url=https://cetinkayakoc.net/docs/r14.pdf |journal=Handbook of Formal Analysis and Verification in Cryptography |pages=1–56 |doi=10.1201/9781003090052-1 |isbn=978-1-003-09005-2}}</ref> In the paper, Shannon defined [[unicity distance]], and the principles of [[confusion and diffusion]], which are key to a secure cipher.<ref>{{Cite book |url=https://books.google.com/books?id=1_GeBQAAQBAJ&pg=PA362 |title=Chaos Synchronization and Cryptography for Secure Communications: Applications for Encryption |date=2011 |publisher=Information Science Reference |isbn=978-1-61520-737-4 |editor-last=Banerjee |editor-first=Santo |location=Hershey, PA |pages=362 |language=en |oclc=495781438}}</ref>

Shannon published an earlier version of this research in the formerly classified report ''A Mathematical Theory of Cryptography,'' Memorandum MM 45-110-02, Sept. 1, 1945, Bell Laboratories.<ref>[https://www.iacr.org/museum/shannon/shannon45.pdf A Mathematical Theory of Cryptography]</ref><ref>[http://www.research.att.com/~njas/doc/shannonbib.html Bibliography of Claude Elwood Shannon]</ref> This report also precedes the publication of his "[[A Mathematical Theory of Communication]]", which appeared in 1948.

==See also==
* [[Confusion and diffusion]]
* [[Product cipher]]
* [[One-time pad]]
* [[Unicity distance]]

==Notes==
<references/>

==References==
* Shannon, Claude. "Communication Theory of Secrecy Systems", ''[[Bell System Technical Journal]]'', vol.&nbsp;28('''4'''), page 656&ndash;715, 1949.
* Shannon, Claude. "A Mathematical Theory of Cryptography", Memorandum MM 45-110-02, Sept. 1, 1945, Bell Laboratories.
* https://www.itsoc.org/about/shannon

==External links==
* [http://netlab.cs.ucla.edu/wiki/files/shannon1949.pdf Online retyped copy of the paper] {{Webarchive|url=https://web.archive.org/web/20070605092733/http://netlab.cs.ucla.edu/wiki/files/shannon1949.pdf |date=2007-06-05 }}
* [https://web.archive.org/web/20070218075311/http://www.prism.net/user/dcowley/docs.html Scanned version of the published ''BSTJ'' paper]

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[[Category:History of cryptography]]
[[Category:Cryptography publications]]
[[Category:1945 in science]]
[[Category:1949 documents]]
[[Category:1949 in science]]
[[Category:1945 documents]]
[[Category:Mathematics papers]]


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