Explain xkcd: It's 'cause you're dumb.
Title text: Not sure why I just taught everyone to flawlessly impersonate me to pretty much anyone I know. Just remember to constantly bring up how cool it is that birds are dinosaurs and you'll be set.
Cueball lost the server password and is asking Megan what it is. Megan correctly comments that she can't be sure through text-based messages that it's really Cueball asking for the password; it could be someone impersonating him attempting to socially engineer access to the server. Cueball answers by starting to develop a cryptographic protocol they can use for proof of identity, probably something like OTR Messaging as implemented in many XMPP chat clients or Feige–Fiat–Shamir identification scheme (in reality, it would already be too late for that—they should have prepared something beforehand). Before he even finishes, Megan answers "It's you", meaning that no one else is so geeky that they would answer like that. Cueball wants to stop her before she discloses the password since he hasn't yet properly proved his identity.
RSA-style encryption uses two large prime, randomly chosen, numbers that when multiplied together form the public key in a public/private key-pair. This algorithm relies on the extreme difficulty in factoring large numbers into their prime components. The public key can be used to encrypt a message that can only (where only is a term used to mean without incredible computation power and time) be decrypted by the use of the private key.
In the title text, Randall suggests that this is, in fact, his own personality, and that anyone reading the comic can now impersonate him. For a bonus, he notes his own fascination with the fact that birds are descendants of dinosaurs, which one could use to impersonate him as well.
- Cueball: Hey, I lost the server password. What is it, again?
- Megan: It's— ...Wait. How do I know it's really you?
- Cueball: OOH, good question! I bet we can construct a cool proof-of-identity protocol. I'll start by picking two random—
- Megan (over text message):Oh good; it's you. Here's the password...
- Cueball: NO!
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He could also be bothered by her willingness to give away the password so easily. Anyone who has spent a sufficient amount of time with the character would have an idea of the things he's interested in. The image text supports it a little by saying how anyone he knows would be aware that he acts like that. 22.214.171.124 08:57, 15 October 2012 (UTC)
They could also be using a version of Google Wave or some such IM... It was possible to view realtime what the others were typing on the window. Then Megan would be able to interrupt Cueball easily.
Notably, although the characters appear to be communicating by way of text (whether SMS, or some instant messaging protocol), Megan should not be able to interrupt Cueball. Text-based messages do not typically stream in realtime as they are typed. She wouldn't be able to read his message until he completed it and sent it. -- TheHYPO (talk) (please sign your comments with ~~~~)
- Unless they are using something like the unix talk command, which does stream characters as they are typed. This might make sense since they are conversing about a server password, but talk might also perform proper authentication, although it could likely be spoofed as most early unix programs were not very secure. The characters are not streamed in real time, by the way, because there is no deadline for transmission of the characters. Sending something "as soon as possible" is pretty much the opposite of "real-time" and I think this wiki should make great efforts to be extra geeky about the use of the phrase "real-time" treating it like "real-time operating system" rather than "I use the web so I think the word 'real-time' means that time itself is not fake." Has Randall written a comic about the misuse of the phrase "real-time"? He should. -- Jsbqvb (talk) (please sign your comments with ~~~~)
- I'm going to quibble over your quibbling over semantics for a moment. "Real-time communication" is not simply saying something immediately after another person. Imagine you and I are sitting in plush armchairs in my front parlour, discussing philosophy. You ask me "What is real-time communication?" I look up to the ceiling, as I formulate my response. According to your definition, this conversation has now left real-time, and become a no-deadline-for-transmission delayed communication, because I've failed to respond immediately. Another example, we're sitting in a park outside at a marble chess table. You move your rook. I study the game board before making my own move. Are you going to argue that this is no longer a real-time game because of my delay?
- A third example. I sit down in my writing room and write a lengthy letter addressed to you and put it into the mail. My postman picks up the mail later that day. It gets sorted and put onto a truck to your house. The truck drives across state lines to the distribution center near your house. The letter gets put in your postman's sack, and that day on his rounds he delivers it to your postbox. You read it and write your response. Your postman picks it up the next day, it's trucked back to my state and delivered to me 2 days after you wrote it. Is this real-time communication? I'll answer that one for you. No it isn't.
- What makes communication real-time, and what doesn't? I don't have a hard-and-fast definition for you. I consider, talking to a person whether face-to-face or over the phone real-time. I consider sending mail and email delayed communication. Instant Messages are real-time if I get an answer within five minutes of when I sent them, same with text messages. So is five minutes a good differentiating line? Here's another example.
- We're in grade school, and we're all sitting in a circle playing Telephone. I whisper the message to my neighbor, who whispers it on until it reaches you, at the other end of the circle. The whole game takes perhaps a minute. Is this real-time communication? No, because I'm passing the message to middle-men. But that's how messages travel the Internet, bouncing through routers until they reach you. So, it can't be that there are no middle-men involved.
- In conclusion. I think your argument that "somewhat delayed delivery of a response" would be a better phrase instead of "real-time" is fallacious, and pointless. That we need to be cautious of the usage of "real-time communication" is not one of the things I think we need to be worried about. I do think we need to be careful of how we rear the upcoming generations, pay attention to the difference between "loose" and "lose", how to spell "onomatopoeia" and "definitely" correctly, as well as using "literally" accurately, "who" vs. "whom", when to and more importantly when not to dangle prepositions, learning when to use which dashes, avoiding ad hominem arguments, trying to be a little less pedantic with others, and taking some time to slow down and smell the flowers and enjoy the scenery.
- --lcarsos (talk) 19:11, 16 October 2012 (UTC)
- I agree with the action plan given in your final paragraph. However, while I don't disagree with your point, your example about the chess game might be a little confusing for some because in games there is a rather well established usage of "real time" games as being in direct opposition to "turn-based" games. Here "real time" usually means that the action all happens continuously and simultaneously, whereas "turn-based" means that everything proceeds by turns (i.e. I make a move, then you do, then me again, etc.), such as in chess. Erenan (talk) 15:51, 24 October 2012 (UTC)
- Moved here from the explanation. lcarsos (talk) 16:56, 15 October 2012 (UTC)
- If you say something, the sound of your voice is spreading by speed of sound, which is relatively slow. What communication can actually be called real-time by the "no delay" definition? Telepathy? -- Hkmaly (talk) 08:40, 17 October 2012 (UTC)
- It's possible that by utilizing quantum entanglement we may be able to achieve communication of information without any delay. I may be wrong about this. Anyone with more knowledge about it care to correct me? Erenan (talk) 20:40, 23 October 2012 (UTC)
My understanding would be that instantaneous communication is impossible. Communication implies a transfer of information of some kind (regardless of how useful it is). Since in order to receive information into the human mind you atteh very least must wait the tiny amount of time for your nerves to transmit their signals from the sensory nerves to the brain. Add to that the assumption of travel via light waves which take time and or sound waves which take longer to arrive at the sensory organ. Even if a device could use a technology to have information come out as soon as it goes in somewhere else, you will have to wait again for the nerves if you surgically implant the the device. Why go through all that trouble and not go the next logical step. If time travel is incorporated you could include the lag so that the trip is finished at the same time it arrived. Of course you could also send yourself a message from the future to not waste Jorge time and to get a life. DruidDriver (talk) 22:13, 22 January 2013 (UTC)
It's possible that he was sending each sentence separately, and she's responding to one of the ones he already completed. 126.96.36.199 18:33, 15 October 2012 (UTC)
The "NO!" may not be for security but the disappointment of missed opportunity to design a 'cool' identity proof protocol.
- While it's true he hasn't yet properly proved his identity, the "NO!" is DEFINITELY the disappointment of missed opportunity to design a 'cool' identity proof protocol. -- Hkmaly (talk) 08:40, 17 October 2012 (UTC)
They could be using skype (mobile and on PC with mic) to communicate, not necessarily text.
- Seriously, why would any of you NOT think that they were using a speakerphone to communicate? (be it through the phone, skype or gtalk or whatever service)? You even got the little "sound wave" lines coming from the devices as the character communicates. 188.8.131.52 13:38, 23 October 2012 (UTC)
- Cueball is holding his phone with two hands. He's clearly texting. The "sound wave" lines are clearly meant to indicate that it's what the character is typing/texting. Also, the transcript indicates that Megan's text in the third frame is a text message (the parenthetical is here only because it's the only place where text is present from a character not visible in the image). Erenan (talk) 00:00, 2 November 2012 (UTC)
- That's the dumbest thing I've ever read. And I've read a LOT. Who needs two hands to text, and why can't someone hold a phone with both hands when on speaker? Furthermore, the transcript has NO BEARING AT ALL on discussions of the comic, because it's subjective. 184.108.40.206 04:54, 14 November 2012 (UTC)
- Never mind, Erenan, I just saw your user-page and your pages. You've got enough issues. You're right, of course, there's no conceivable way Cueball could be doing anything but texting. It's "clear", and the sound wave lines "clearly" indicate that as well. I stand corrected. Enjoy life. You're "clearly" very smart and always right. 220.127.116.11 04:58, 14 November 2012 (UTC)
- At no point is there a need to personally attack another commenter on this site like that. Also, do not edit other people's posts on a talk page, that is rude in the extreme. Come back in a week, maybe you can keep a civil tongue in your head. lcarsos_a (talk) 05:12, 14 November 2012 (UTC)
- Wiki etiquette states that you do not touch other people's comments - replacing his name with "dumbo" is childish. As for the transcript, it came from the div with id "transcript" in the source on the XKCD website. I believe Randall knows his own comics well enough Davidy22(talk) 05:16, 14 November 2012 (UTC)
- Link as source for Davidy's statement. Go forth and educate thineself. lcarsos_a (talk) 05:21, 14 November 2012 (UTC)
The reference to dinosaur fascination might be a last ditch attempt to try and fool people who MIT try and impersonate Randall. My understanding which may be flawed is that Randal has a fear around raptors, and close friends might hear praise for these and get suspicious if the leave out the fear part. DruidDriver (talk) 22:13, 22 January 2013 (UTC)
To support the feasibility of what happens in the last panel, it could be that Megan doesn't have the password in mind, and hit 'Enter' to go look for the password elsewhere. 18.104.22.168 20:37, 9 February 2014 (UTC)
The paragraph about RSA encryption, though interesting, is irrelevant to the explanation of the comic, as there is nothing to indicate he intends to use it (Seriously, who can name random large primes off the top of their head?). As such, I'm going to delete it.22.214.171.124 02:29, 11 February 2014 (UTC)
The entire conversation is perfectly understandable if their voices were reversed, and Megan was saying Cueballs lines, while Cueball Megans lines. Thisfox (talk) 10:57, 21 May 2015 (UTC)