<p>Fictional characters. Cryptography (and other) books use names like that often.</p>

<p><a href="http://en.wikipedia.org/wiki/Alice_and_Bob">http://en.wikipedia.org/wiki/Alice_and_Bob</a></p>

CC BY-SA 3.0
2014-05-16T01:56:32.090Z
2014-05-16T01:56:32.090Z
Matt
<p>Alice and Bob are <a href="http://en.wikipedia.org/wiki/Alice_and_Bob" rel="nofollow noreferrer">placeholder characters</a> corresponding to the letters of the alphabet. They are used especially in computer science to describe use-cases or scenarios. The scheme is used because it's more convenient to say <em>&quot;Alice sends money to Bob&quot;</em> than to say <em>&quot;Party A sends money to Party B&quot;</em>. As each name has a different initial, diagrams can fall back to single letter labeling.</p>
<p>It's a well-known meme:</p>
<p><a href="https://imgs.xkcd.com/comics/protocol.png" rel="nofollow noreferrer"><img src="https://imgs.xkcd.com/comics/protocol.png" alt="Obligatory XKCD" /></a><br />
<sup>via <a href="https://xkcd.com/1323/" rel="nofollow noreferrer">xkcd.com</a></sup></p>
<p>The list usually goes something like this: <strong>A</strong>lice, <strong>B</strong>ob, <strong>C</strong>harlie, <strong>D</strong>ave, <strong>E</strong>rin, <strong>F</strong>rank,…</p>
<p>Other names are used to represent attacker types or other recurring roles:</p>
<ul>
<li><strong>C</strong>arole, the oracle</li>
<li><strong>E</strong>ve, the eavesdropper</li>
<li><strong>M</strong>allory, the man-in-the-middle attacker with <strong>mal</strong>icious intent</li>
<li><strong>S</strong>ybil, the attacker with lots of identities</li>
<li><strong>T</strong>rent, the <strong>tr</strong>usted <strong>ent</strong>ity</li>
</ul>

CC BY-SA 4.0
2016-03-18T08:57:36.810Z
2020-12-03T16:32:22.503Z
2020-12-03T16:32:22.503Z
Murch
<p>Simply: who are Alice and Bob, and why are they mentioned in every Bitcoin-related article I read about that talks about Bitcoin transactions?</p>
<p>What is the history or mystery of these two?</p>

<terminology>
Who are Alice and Bob?
Sky
# Who are Alice and Bob?

(Asked by: username_0 on 2014-05-16)

Simply: who are Alice and Bob, and why are they mentioned in every Bitcoin-related article I read about that talks about Bitcoin transactions?

What is the history or mystery of these two?

**Tags:** terminology


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## 2 answers

### Answer by username_1 on 2014-05-16. Score: 6

Fictional characters. Cryptography (and other) books use names like that often.

<http://en.wikipedia.org/wiki/Alice_and_Bob>


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### Answer by username_2 on 2016-03-18. Score: 5

Alice and Bob are [placeholder characters](http://en.wikipedia.org/wiki/Alice_and_Bob) corresponding to the letters of the alphabet. They are used especially in computer science to describe use-cases or scenarios. The scheme is used because it's more convenient to say *"Alice sends money to Bob"* than to say *"Party A sends money to Party B"*. As each name has a different initial, diagrams can fall back to single letter labeling.

It's a well-known meme:

[![Obligatory XKCD](https://imgs.xkcd.com/comics/protocol.png)](https://imgs.xkcd.com/comics/protocol.png)  
via [xkcd.com](https://xkcd.com/1323/)

The list usually goes something like this: **A**lice, **B**ob, **C**harlie, **D**ave, **E**rin, **F**rank,…

Other names are used to represent attacker types or other recurring roles:

* **C**arole, the oracle
* **E**ve, the eavesdropper
* **M**allory, the man-in-the-middle attacker with **mal**icious intent
* **S**ybil, the attacker with lots of identities
* **T**rent, the **tr**usted **ent**ity


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