A brief history of Alice & Bob, cryptography's first couple

Originally published at: http://boingboing.net/2017/07/19/heteronormative-exemplars.html



Well traditionally, the cryptographers aren’t as sexist at the guys over in image processing… https://en.wikipedia.org/wiki/Lenna



Thanks @doctorow passed this on to some of my crypto head buddies, we got to chatting about how often we end up using localized names since lots of us are in places where Alice and Bob don’t quite work.

Here in Japan we usually use Hanako and Taro just because they are common names.


Quickly, the XKCD!


Came for this- what about Carol and Ted, what are they, chopped liver?

And don’t get me started on Alice, she doesn’t even live here anymore.


I heard she sold the restaurant to some blockchain.

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I’ve always assumed that the pattern was simply alphabetical: a message passes through Alice at point A to Bob at point B, possible going through points C (Charlie), D (David), E (Ernie*), and F (Frank).

(* And yes, I could have gone with Emily, but that’s three syllables, not one or two. Brevity.)

The bit in the article about Eve (eavesdropper) and mallory (malicious actor) was cute, but new to me.

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I heard the same from Bruce Schnerer and PKZ but it could also be a game of telephone.

Of course alphabetical order is different in Japanese and the tendency is to go for the common over the strictly correct, thus Hanako and Taro.

I am reminded of this passage from Neal Stephenson’s Cryptonomicon:

“It’s like this. Alfred has some money that he wants to invest.”

“Who’s Alfred?”

“A hypothetical person whose name begins with A.”

“I don’t understand.”

“In the crypto world, when you are explaining a cryptographic protocol, you use hypothetical people. Alice, Bob, Carol, Dave, Evan, Fred, Greg, and so on.”


“Alfred invests his money in a company that is run by Barney. When I say ‘run by’ what I mean is that Barney has ultimate responsibility for what that company does. So, perhaps Barney is the chairman of the board of directors in this case. He’s been chosen, by Alfred, Alice, Agnes, Andrew, and the other investors, to look after the company. He and the other directors hire corporate officers—such as Chuck, who is the president. Chuck and the other officers hire Drew to run one of the company’s divisions. Drew hires Edgar, the engineer, and so on and so forth. So, in military terms, there is a whole chain of command that extends down to the guys in the trenches, like Edgar.”

“And Barney’s the man at the top of the chain of the command,” Doug says.

“Right. So, just like a general, he is ultimately responsible for everything that is done below him. Alfred has personally entrusted Barney with that money. Barney is legally required to exercise due diligence in seeing that the money is spent responsibly. If Barney fails to show due diligence, he is in major legal trouble.”


“Yeah. That gets Barney’s attention. Alfred’s lawyers might show up at any moment and demand proof that due diligence is being exercised. Barney needs to stay on his toes, make sure that his ass is covered at all times.”

“Barney in this case is the Dentist?”

“Yeah. Alfred, Agnes, and the others are all of the people in his investment club—half of the orthodontists in Orange County.”

“And you are Edgar the Engineer.”

“No, you are Edgar the Engineer. I am a corporate officer of Epiphyte. I am more like Chuck or Drew.”

Source: http://cnqzu.com/library/Anarchy%20Folder/Fiction/Stephenson,_Neal/Stephenson,Neal-_Cryptonomicon/Neal%20Stephenson%20-%20Cryptonomicon%20v2%20(HTML,%20Fully%20Proofed)/slide51.html

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Be sure to actually “download” the fulltext, unless you don’t really care for anecdotes.


Also worth reading: and mentioned in the above essay.


In papers written by American authors Bob is frequently selling stock to speculators. From the number of stock market deals Bob is involved in we infer that he is probably a stockbroker. However from his concern about eavesdropping he is probably active in some subversive enterprise as well. And from the number of times Alice tries to buy stock from him we infer she is probably a speculator. Alice is also concerned that her financial dealings with Bob are not brought to the attention of her husband. So Bob is a subversive stockbroker and Alice is a two-timing speculator.
But Alice has a number of serious problems. She and Bob only get to talk by telephone or by electronic mail. In the country where they live the telephone service is very expensive. And Alice and Bob are cheapskates. So the first thing Alice must do is MINIMIZE THE COST OF THE PHONE CALL.
The telephone is also very noisy. Often the interference is so bad that Alice and Bob can hardly hear each other. On top of that Alice and Bob have very powerful enemies. One of their enemies is the Tax Authority. Another is the Secret Police. This is a pity, since their favorite topics of discussion are tax frauds and overthrowing the government.
These enemies have almost unlimited resources. They always listen in to telephone conversations between Alice and Bob. And these enemies are very sneaky. One of their favorite tricks is to telephone Alice and pretend to be Bob.
Well, you think, so all Alice has to do is listen very carefully to be sure she recognizes Bob’s voice. But no. You see Alice has never met Bob. She has no idea what his voice sounds like.

Even better


Mallory as malicious eavesdropping actor? Tell me more.

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The whole gang is here. Alice, Bob, Trent, Mallory, and Eve.

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