Editing 2691: Encryption

{{comic
| number    = 2691
| date      = October 28, 2022
| title     = Encryption
| image     = encryption_2x.png
| imagesize = 235x380px
| noexpand  = true
| titletext = WARNING: PEOPLE NAMED EVE ARE PROHIBITED FROM INSTALLING THIS APP!
}}

==Explanation==

When teaching encryption / cryptography, it is common to use a story about sending messages from {{w|Alice and Bob|Alice to Bob}} (Party "A" and Party "B" respectively). Cueball claims to have created a texting app that only allows for this one thing. It does not, however, allow "Bob" to reply, making the usefulness of the app questionable at best. It is unclear how it enforces the name restriction, but it is possible that the app figures out the name of the phone's owner. The title text mentions Eve, who in the typical story represents an "eavesdropper", someone who attempts to intercept the messages between Alice and Bob.  The fact that persons named Eve are 'forbidden' from installing the app suggests that it might not actually be as secure as Cueball advertises -- it may be that he naively thinks that it's just the name that makes the eavesdropper, and that by excluding all Eves, Alice's messages to Bob will remain private. It is not clear which phones will support this app, but it appears to be perfectly suited for the [[:Category:xkcd Phones|xkcd Phones]].

Note also that Eve being forbidden to install the app parallels another Eve being forbidden to eat an apple (an app-le?) in a common retelling of the Biblical story of the Garden of Eden (though the actual Biblical text doesn't refer to an apple).  Spoiler alert: The Biblical Eve ate the forbidden fruit anyway, and this Eve is probably going to install the app anyway...

The comics [[177: Alice and Bob]] and [[1323: Protocol]] are also about Alice and Bob.

If the names of the users don't need to be verified, it seems possible to circumvent the security features of the app with double installations and a complete mess of a contact list in which everyone's names are somehow identified as "Alice" or "Bob". Also, it would appear that "Bob" needn't be the commonly used name of the message receiver, in this scenario – it could also be a diminutive of what he is actually known by. Thus a user might claim to be "Bob" whichever his given name is.

This may be related to the announcement that {{w|Signal (software)|Signal}} would be discontinuing support for SMS/MMS messages.

==Transcript==
:[Cueball showing a phone to a long-haired woman, identified in the caption as Alice]
:Cueball: The app will let you send messages to your friend Robert, or my brother.
:Alice: Can they reply?
:Cueball: No.

:[Caption below the panel]:
:My new secure texting app only allows people named Alice to send messages to people named Bob.

{{comic discussion}}
[[Category: Comics featuring Cueball]]
[[Category: Cryptography]]
[[Category: Smartphones]]