Alice and Bob: Difference between revisions
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'''Alice''' and '''Bob''', also just '''A''' and '''B''', are the standard example users in writing on [[cryptography]], [[coding theory]], communication complexity theory etc. Carol and Dave often join them for protocols that require more than two players. | '''Alice''' and '''Bob''', also just '''A''' and '''B''', are the standard example users in writing on [[cryptography]], [[coding theory]], communication complexity theory etc. Carol and Dave often join them for protocols that require more than two players. | ||
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== History == | == History == | ||
Alice and Bob were introduced in the original paper <ref>{{citation | Alice and Bob were introduced in the original paper (1978)<ref>{{citation | ||
| author = Rivest, Shamir & Adleman | | author = Rivest, Shamir & Adleman | ||
| title = A Method for Obtaining Digital Signatures and Public-Key Cryptosystems | | title = A Method for Obtaining Digital Signatures and Public-Key Cryptosystems | ||
| journal = Commun. ACM | volume = 21 | pages = 120-126 ([http://people.csail.mit.edu/rivest/Rsapaper.pdf pdf]) | |||
| date = 1978}}</ref> | | date = 1978}}</ref> | ||
on the [[RSA algorithm]] for [[public key]] cryptography. | on the [[RSA algorithm]] for [[public key]] cryptography. | ||
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While Alice and Bob are standard in cryptography and coding theory, other pairs of players are used in other domains. | While Alice and Bob are standard in cryptography and coding theory, other pairs of players are used in other domains. | ||
'''Arthur''' and '''Merlin''' were introduced by László Babai (1985)<ref> | |||
László Babai, ''Trading group theory for randomness''. | |||
STOC '85 Proceedings of the seventeenth annual ACM symposium on Theory of computing, ACM. 421–429 (1985), | |||
([http://dl.acm.org/citation.cfm?id=22192 abstract]) | |||
</ref>. | |||
This pair is used in [[computational complexity theory]] for [[interactive proof system]]s: | |||
Merlin, the wizard, is the nondeterministic player (with unbounded computational power) | |||
who wants to convince the random player Arthur of the truth of a statement. | |||
'''Paul''' (the Pusher) and '''Carole''' (the Chooser) were introduced by Joel Spencer and Peter Winkler (1992)<ref> | |||
{{citation |last1=Spencer|first1=Joel|author1-link=Joel Spencer | last2=Winkler|first2=Peter|author2-link=Peter Winkler | title=Three Thresholds for a Liar | journal=Combinatorics, Probability and Computing | year=1992 | volume=1 | pages=81–93 ([http://math.dartmouth.edu/~pw/papers/3thresh.ps Postscript])}}</ref> | |||
in their study of the [[Twenty Questions]] game (with lies) where Paul asks the questions and Carole answers them. | |||
In this pair "Paul" refers to Pál (=Paul) [[Pál Erdős|Erdős]], and "Carole" is an [[anagram]] of "oracle". | |||
Since then these names have been used for various similar roles in [[combinatorial game theory]]. | |||
In English grammar discussions, notably in [[Noam Chomsky]]'s writings, '''John''' and '''Mary''' are often used. | In English grammar discussions, notably in [[Noam Chomsky]]'s writings, '''John''' and '''Mary''' are often used. | ||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}}[[Category:Suggestion Bot Tag]] |
Latest revision as of 16:00, 8 July 2024
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Alice and Bob, also just A and B, are the standard example users in writing on cryptography, coding theory, communication complexity theory etc. Carol and Dave often join them for protocols that require more than two players.
Bruce Schneier extends these [2] with two kinds of attacker:
and several other types of player required in various protocols:
Schneier's extensions seem to be in the process of becoming standard as well. There is even an XKCD cartoon with Eve being jealous of Alice over Bob. It is also moderately common to add additional characters as needed for a particular protocol. For example, in discussing a e-commerce system, one might need Matlida the Merchant and Ivan the Issuer of credentials. HistoryAlice and Bob were introduced in the original paper (1978)[3] on the RSA algorithm for public key cryptography.
The similar name of the film Bob & Carol & Ted & Alice and subsequent TV show appears to be just a coincidence. Rivest denies that there is a connection. Alice and Bob have an amusing biography on the web.
Other pairsWhile Alice and Bob are standard in cryptography and coding theory, other pairs of players are used in other domains. Arthur and Merlin were introduced by László Babai (1985)[5]. This pair is used in computational complexity theory for interactive proof systems: Merlin, the wizard, is the nondeterministic player (with unbounded computational power) who wants to convince the random player Arthur of the truth of a statement. Paul (the Pusher) and Carole (the Chooser) were introduced by Joel Spencer and Peter Winkler (1992)[6] in their study of the Twenty Questions game (with lies) where Paul asks the questions and Carole answers them. In this pair "Paul" refers to Pál (=Paul) Erdős, and "Carole" is an anagram of "oracle". Since then these names have been used for various similar roles in combinatorial game theory. In English grammar discussions, notably in Noam Chomsky's writings, John and Mary are often used. References
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