The Weasley twins told Harry that the password to the map was: "I solemnly swear that I am up to no good". But how could THEY have known it? It's not exactly LOTR's Moria door with "12345" level of security—you do not have a plaintext password hint (or any).

  • @Izkata - as Lifehacker keeps pounding into people day after day, "you don't achieve higher productivity by multitasking" :) Commented Oct 5, 2012 at 15:56
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    That's easy. Just write a spell that does a dictionary attack. They're not bound by any deterministic constraints, so it should succeed rather quickly.
    – John O
    Commented Oct 5, 2012 at 16:06
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    @JohnO - well, we already know that Potterverse magical theory has SQL WHERE clauses Commented Nov 12, 2013 at 15:49
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    Maybe a pet rat whispered to them in their sleep?
    – RichS
    Commented Jul 30, 2017 at 2:01
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    Just as a general question, was the password required to be correct word for word, or did it simply need to convey the same message? If it's the latter, then it's incredibly likely that either of them said something like this at one point or another. Also, do we even know that there was only one password? F&G simply passed on the password they knew; but we can't know if they ever checked for other viable passwords.
    – Flater
    Commented Dec 1, 2017 at 13:26

2 Answers 2


JKR answered this in one of the interviews. AFAIR, the process in her mind was, quite surprisingly, not unlike real life hacking (you probe and poke around and change the attack based on system feedback to your trial-and-error attempts).

From "MuggleNet and The Leaky Cauldron interview Joanne Kathleen Rowling"

July 16, 2005: Harry Potter and the Half-Blood Prince publication day Edinburgh, Scotland - Part Three.

MA: How did they figure out how to work the map?
JKR: Don't you - well. This is how I explained it to myself at the time, and this does sound glib. Don't you think it would be quite a Fred and Georgeish thing to say in jest, and then see this thing transform?
MA: Yeah.
JKR: Can't you just see them?
ES: But the exact word combination? Is that just a lot of luck, or Felix Felicis -
JKR: Or, the map helped.
MA: Yep, yeah. You can see them sort of answering and joking with each other -
JKR: And the map flickering into life here and there when they got closer and closer, and finally they hit upon the exact right word combination and it just erupts.

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    +1 The map was definitely interactive, and you can just see it asking Fred and George whether they were up to no good or not.
    – NominSim
    Commented Oct 5, 2012 at 15:47
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    @NominSim - "It looks like you are trying to do mischief. Would you like help?" </clippy> Commented Nov 12, 2013 at 15:47
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    @MishaRosnach go look at hacked datasets where the password hint that many sites allow are revealed. Many of them give way too much help.
    – mikeazo
    Commented Feb 11, 2015 at 12:38
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    @MishaRosnach: As the Sorting Hat shows, magic can detect your potential and intent. I'm willing to bet the Map could detect those who intended to use it for fun (as opposed to harm or rule enforcement) and give hints to them. Look what it did for Snape, after all.
    – Jeff
    Commented Mar 17, 2015 at 14:55
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    Their jokes and general behaviour tended to obscure the fact that Fred and George were very creative and talented wizards. They probably worked much harder on a challenge like cracking the map then on their schoolwork. Commented Aug 10, 2016 at 14:35

Fred and George simply used the process of trial and error. Its very possible that the map recognized them to be very mischevious, so when they got the password wrong, it gave them a little hint that they were getting closer. The Marauders probably made it so the password would be something that trouble-makers could think of. It probably wouldn't help anyone who wasn't up to no good. After all, it was specifically made for mischief.

  • 1
    Welcome to SciFi.SE! If you sign up for a proper account, you can edit your answer instead of having to post an entirely new answer.
    – F1Krazy
    Commented Mar 29, 2018 at 22:04
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    Providing a source for your claims will help improve the quality of your answer.
    – Edlothiad
    Commented Mar 29, 2018 at 22:13

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