Alice and Bob/Analysis
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. 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's 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. —John Gordon, explaining the many and varied proclivities and problems of everyone's favorite fictional duo.
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If you've wandered through All The Tropes, you may have noticed that when people reach for two generic names to give to characters in an example, the names will be, almost unerringly, Alice and Bob. And as you might suspect, this isn't a coincidence - Alice and Bob have traditionally been used as the names of the two parties involved in examples in a number of fields, most famously in cryptography. In fact, it was the seminal paper outlining the RSA asynchronous encryption algorithm that introduced Alice and Bob to the world.
The reason that this duo is used continually is because they're a simple yet elegant shorthand for saying "Party A" and "Party B". When you start talking about "Alice wants to send a message to Bob", it immediately sets up the situation without requiring a lot of exposition. And as their usage became more popular in cryptography and then geek circles, they've popped up in more and more mainstream venues.
Unsurprisingly, there's a whole cast of characters involved in Alice and Bob's adventures, and they too have been standardized:
- Carol/Carlos/Charlie/Chuck: The third party ("Party C") in three way communications. Chuck is usually reserved for situations where the third party has malicious intent.
- Dave: The fourth party ("Party D", natch) in four way communications.
- Eve: A passive eavesdropper. Tries to listen in, but doesn't attempt to actively alter the communication like Mallory (see below).
- Mallory: A malicious intruder. Unlike her passive counterpart Eve, Mallory doesn't just read messages, but can actively interfere in the communications (e.g. edit, delay, or prevent delivery of messages).
- Peggy: A prover. Her job is to act as third party proof of transactions taking place.
- Trent: A trusted arbitrator. A third party known as trustworthy and neutral to the other parties involved. His exact role may vary based on the system being used.
- Walter: A warden. His job is to protect the participants in the communication.
- Victor: A verifier. He provides third party verification, similar to Peggy.
One thing that you may have noticed - and the University of Edinburgh definitely did notice in 2021 - is that all of those names are Western European in origin. If this bothers you, feel free to use other names in place of Alice and Bob – perhaps Aistė and Benas, Amahle and Bongani, Amala and Bharath, Awinita and Sequoyah, Aya and Ryo, or even Aerith and Bob if you like mixing and matching.
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