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<html xmlns="http://www.w3.org/1999/xhtml"><head><title>Alice and Bob</title><link rel="stylesheet" href="../../jargon.css" type="text/css"/><meta name="generator" content="DocBook XSL Stylesheets V1.61.0"/><link rel="home" href="../index.html" title="The Jargon File"/><link rel="up" href="../A.html" title="A"/><link rel="previous" href="aliasing-bug.html" title="aliasing bug"/><link rel="next" href="All-hardware-sucks--all-software-sucks-.html" title="All hardware sucks, all software sucks."/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Alice and Bob</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="aliasing-bug.html">Prev</a> </td><th width="60%" align="center">A</th><td width="20%" align="right"> <a accesskey="n" href="All-hardware-sucks--all-software-sucks-.html">Next</a></td></tr></table><hr/></div><dt><a id="Alice-and-Bob"/><dt xmlns="" id="Alice-and-Bob"><b>Alice and Bob</b>: <span xmlns="http://www.w3.org/1999/xhtml" class="grammar">n.</span></dt></dt><dd><p> The archetypal individuals used as examples in discussions of
cryptographic protocols. Originally, theorists would say something like:
&#8220;<span class="quote">A communicates with someone who claims to be B, So to be sure, A
tests that B knows a secret number K. So A sends to B a random number X. B
then forms Y by encrypting X under key K and sends Y back to A</span>&#8221;
Because this sort of thing is quite hard to follow, theorists stopped using
the unadorned letters A and B to represent the main players and started
calling them Alice and Bob. So now we say &#8220;<span class="quote">Alice communicates with
someone claiming to be Bob, and to be sure, Alice tests that Bob knows a
secret number K. Alice sends to Bob a random number X. Bob then forms Y by
encrypting X under key K and sends Y back to Alice</span>&#8221;. A whole
mythology rapidly grew up around the metasyntactic names; see <a href="http://www.conceptlabs.co.uk/alicebob.html" target="_top">http://www.conceptlabs.co.uk/alicebob.html</a>.</p></dd><dd><p>In Bruce Schneier's definitive introductory text <i class="citetitle">Applied
Cryptography</i> (2nd ed., 1996, John Wiley &amp; Sons, ISBN
0-471-11709-9) he introduced a table of dramatis personae headed by Alice
and Bob. Others include Carol (a participant in three- and four-party
protocols), Dave (a participant in four-party protocols), Eve (an
eavesdropper), Mallory (a malicious active attacker), Trent (a trusted
arbitrator), Walter (a warden), Peggy (a prover) and Victor (a verifier).
These names for roles are either already standard or, given the wide
popularity of the book, may be expected to quickly become so.</p></dd><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="aliasing-bug.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="../A.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="All-hardware-sucks--all-software-sucks-.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">aliasing bug </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> All hardware sucks, all software sucks.</td></tr></table></div></body></html>