Alice and Bob

Alice and Bob, also just A and B, are the standard example users in writing on cryptography and coding theory. Carol and Dave often join them for protocols that require more than two players.

Bruce Schneier extends these with two kinds of attacker:

• Eve the Eavesdropper, using passive attacks
• Mallory the Malicious, using active attacks

and several other types of player required in various protocols:

• Victor the Verifier
• Peggy the Prover
• Trent the Trusted third party
• Walter the Warden

His extensions seem to be in the process of becoming standard as well.

Alice and Bob have an amusing biography on the web.

Now there are hundreds of papers written about Alice and Bob. Over the years Alice and Bob have tried to defraud insurance companies, they've played poker for high stakes by mail, and they've exchanged secret messages over tapped telephones.

If we put together snippets from lots of papers, we get a fascinating picture of their lives. This may be the first time a definitive biography of Alice and Bob has been given. ...

Against all odds, over a noisy telephone line, tapped by the tax authorities and the secret police, Alice will happily attempt, with someone she doesn't trust, whom she cannot hear clearly, and who is probably someone else, to fiddle her tax returns and to organise a coup d'etat, while at the same time minimising the cost of the phone call.

A coding theorist is someone who doesn't think Alice is crazy.

The similar name of the film Bob & Carol & Ted & Alice and subsequent TV show appears to be just a coincidence.