Alice and Bob

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When the interaction between two hypothetical characters is needed to explain or describe some system, they are nearly always called Alice and Bob. Alice and Bob - A and B. This duo originally started out as a standardized way to explain cryptography. Over time, the duo has been adopted in explanations of mathematics, physics, quantum effects, and other arcane places, but have also been seen in fiction. They are also found in a surprising number of trope definitions.

Where more than two characters are needed, other names are used, such as Carol and Charlie. Some names have acquired standard meanings, such as Eve the Eavesdropper. Lists of these can be found in Bruce Schneier's book Applied Cryptography, and at that other wiki.

Note that the most common names are "Alice", "Bob" and "Charlie/Charley". This works for most situations.

The use of Alice and Bob is suggested in General Suggestions, but some of us (notably those who really are called Alice and/or Bob) sometimes wish a little imagination could be applied. That's where Aerith and Bob come in. Or Jim and Mary. Or Dick and Jane.

See also Those Two Guys, Greek Chorus.

Examples of Alice and Bob include:

Film

Literature

  • In most cryptography textbooks, communications are presented as being between Alice and Bob, and must be secured from a third-party interloper named Eve (for Eavesdropper, of course!). If the problem requires the involvement of more than two parties, then Charlie and Donna may be introduced. (This is the basis for the xkcd reference listed below.) Other character names sometimes used for special purposes include Mallory (a malicious active adversary, capable of changing the messages sent between Alice and Bob, whereas Eve merely listens), Trent (a mutually trusted third party, whom Alice and Bob might prevail upon to execute protocols in which they don't trust each other), and Peggy and Victor (the prover and verifier, respectively, in zero-knowledge proofs).
    • Game Theory books often use an adaptation of Alice and Bob in "Rose and Colin" (rows and columns on game theory charts), with "Larry", or "layer" thrown in for three person games.
      • Game Semantics books tend to use Abelard and Eloise (for resemblance to the universal and existental quantifier symbols, which are an inverted A and a backwards E). They are also the names of a medieval logician and his lover.
  • Alice and Bob are the names of the parents in Vernor Vinge's Rainbows End, and a government official is named Eve Mallory.
  • E. R. Emmet's "Our Factory" puzzles feature "Alf", "Bert", "Charlie", and so on.

Live Action TV

  • TV and Movie example: Bob & Carol & Ted & Alice.
  • One of the logos at the end of The Bonnie Hunt Show (2008-2010) is for "Bob & Alice Productions".
    • Bonnie's Hunt's parents are named Bob and Alice so it is either just a reference to her parents or both.

Music Tropes

  • Nerdcore Rap artist MC Plus+ has a song about cryptography named "Alice and Bob".

Newspaper Comics

Oral Tradition

Video Games

  • Used in a very surreal Cyberspace level in World of Goo called "Alice and Bob and the Third Party," where you intercept information-goo transmitted from cosmicGrrrl! to LaconicCrusadr13.
  • Used as examples for an explanation of quantum teleportation in Remember 11.

Web Comics

  • Parodied in this xkcd comic.
  • Alice is introduced in the opening chapter of Freak Angels. In the epilogue, she's explaining the story to a military officer named Bob.

Web Original

Real Life

  • Alice and Bob really are quantum- a professor at the University of Washington has used two separate remote cameras, named Alice and Bob, to test the theory of non-locality and its potential for time travel, by attempting to receive a message before it's sent. The experiment hasn't yielded results so far, but it's telling.
  • In Linguistics, it's more often John and Mary.
  • Named tropical storms (typhoons, hurricanes, cyclones) are based on a sequential list of given names, replaced every year, with a different list for each region. The lists will be re-used at half-dozen year intervals, but with the names of historic "worst" storms periodically retired. That'd make Hurricane Andrew the first (A) tropical storm of the North Atlantic hurricane season in his respective year. Q, U, Z are not used; a particularly bad season (such as 2005 with Dennis, Katrina, Wilma) can exhaust the entire 23-name alphabetical list, after which the Greek alphabet (Hurricane Beta...) is pressed into service. The original lists used female names as meteorologists proposed the names of their sweethearts; more recent practice has alternated gender on each successive storm (so Alex, Brenda, Charles, Diana, Elmer, Francesca... or a similar pattern).
    • A similar alphabetically-sequential naming series was used circa-1883 for a string of Atlantic and Pacific Railroad stops where steam trains took on water across the Mojave Desert. The first was "Amboy", now a ghost town on the former US Route 66. followed (from west to east) with Bristol, Cadiz, Danby, Essex, Fenner, Goffs, Home, Ibis, Java, and Klinefelter. Most of these points are now abandoned.
    • Similar alphabetically-sequential naming patterns have been used for versions of software; Ubuntu uses names of animals this way, while the Android OS used to use names of foodstuffs (beginning after 'B' as the base, "Cupcake", "Donut", Éclair", "Froyo", "Gingerbread", "Honeycomb", "Ice Cream Sandwich", "Jelly Bean", "KitKat", "Lollipop", "Marshmallow", "Nougat", "Oreo", "Pie", ending just before this reached 'Q').

All The Tropes