Quote from: borgx on December 21, 2017, 12:55:38 AM

I imagine someone could write code that keeps trying to repeat 12 different combinations of words, after a while he must get results and control someones funds, no? With the amount of wallets out there now...

The number of possible words can vary per application, but let's assume there are 2048 possible words. That means using 2 words gives 2048*2048 or 2048^2 possibilities, 3 words gives 2048^3 possibilities, and 12 words gives 2048^12 = 5444517870735015415413993718908291383296 possible combinations.
If you assume 1 billion people each use this system on 10 wallets, and you can brute-force 10 billion combinations per second, it'll still take you a trillion years to find a match. It's a lot easier to just find the next Bitcoin block, which is more valuable than most wallets anyway.

I'm bored, I'll go over all replies to this thread:

Quote from: GreatBug on December 21, 2017, 01:19:53 AM

To be honest, I made a normal text file, and later I copied it to external memory and to two other places outside of my personal computer (offline).

Did you only read the title?

Quote from: mjglqw on December 21, 2017, 03:40:52 AM

How many words do we have? More than 150,000?

Most words are ignored for the list, to avoid confusion. For instance, Electrum uses "same", but not "sane". It uses "insane" again, which can't be confused with "same". It also excludes impractical long words, like "impractical".

Quote from: crairezx20 on December 21, 2017, 08:37:27 AM

To me i just save the 12 word seed in notepad and save after that i just make rar file included my 12 word seed in notepad.. with password..

You too didn't read more than the title. Either way, storing seed phrases in a txt-file is bad practice. Write it on paper, or at least use a password manager to store it.

Quote from: A1exander on December 21, 2017, 08:52:59 AM

The chances are very close to 0. The amount of calculations needed for this is incredibly large. Suppose you already know the set of 12 words, but not their order. The number of possible permutations is 12! (12 factorial), which is 479001600.

So far you're correct, although the possibility of duplicate seed words would reduce the number of permutations.

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But there are much more words used for seeds. A meager set of 100 gives the number of permutations of about 9E157 (9 with 157 zeroes), and only millions of them correspond to existing wallets.

Wrong! You're talking about 100 different words that you have, but don't know the order for. 12 words out of 100 possibilities gives 100^12=10^24 possibilties. A 1 with 24 zeroes, you're a factor 9E133 off, which is (based on a high estimate) about 20 sexdecillion times more than the number of atoms in the universe. You, sir, added a new level to "you couldn't be more wrong" Cheesy

Quote from: kahc on December 21, 2017, 04:27:07 PM

I assume the standard BIP0039 wordlist is used here. So you have 2048 words, repetition is also allowed.

Correct.

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So you have a total of

2048! / (2048−12)! = 5271537971301488476000309317528177868800 permutations.

And you, sir, I take my hats off for you, as you're right and I was wrong!
I forgot to include the increase in odds due to the repetition of words.

Quote from: MarkoViewly on December 21, 2017, 04:29:36 PM

Some say it isn't that secure
https://blog.edgesecure.co/why-a-12-word-mnemonic-is-an-insecure-bitcoin-wallet-backup-d56085da6c8d

This article doesn't say the math is wrong, it says displaying the words is the weak link. And I'm pretty sure they are correct! Then again, you'll have similar problems on all other user security methods. Even if you write down your seed, put it in a safe, and store the safe in Fort Knox, it's still much more likely to be found by someone who gets physical access, than the odds of someone else creating the same seed.