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From: Zac Greenwood <zachgrw@gmail.com>
To: Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>,
	 James MacWhyte <macwhyte@gmail.com>
Subject: Re: [bitcoin-dev] No Order Mnemonic
Date: Sat, 9 Jul 2022 22:31:22 +0200	[thread overview]
Message-ID: <CAJ4-pEA7WJpbExcsgdPWVNuZLrbDDhVYr37g6_6NSf7t41eB4w@mail.gmail.com> (raw)
In-Reply-To: <CAH+Axy4X+uQG5Vw0Efiz6AtNyK=++h-jDeZL1ZxpVJus8BVKeA@mail.gmail.com>

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Sorting a seed alphabetically reduces entropy by ~29 bits.

A 12-word seed has (12, 12) permutations or 479 million, which is ln(469m)
/ ln(2) ~= 29 bits of entropy. Sorting removes this entropy entirely,
reducing the seed entropy from 128 to 99 bits.

Zac


On Fri, 8 Jul 2022 at 16:09, James MacWhyte via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

>
> What do you do if the "first" word (of 12), happens to be the last word in
>> the list alphabetically?
>>
>
> That couldn't happen. If one word is the very last from the wordlist, it
> would end up at the end of your mnemonic once you rearrange your 12 words
> alphabetically.
>
> However!
>
> (@vjudeu) Choosing 11 random words and then sorting them alphabetically
> before assigning a checksum would reduce entropy considerably. If you think
> about it, to bruteforce the entire keyspace one would only need to come up
> with every possible combination of 11 words + 1 checksum. I'm not the best
> at napkin math, but I think that leaves you with around 10 trillion
> combinations, which would only take a couple months to exhaust with
> hardware that can do 1 million guesses per second.
>
>
> James
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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  reply	other threads:[~2022-07-09 20:31 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-07 14:33 [bitcoin-dev] No Order Mnemonic Anton Shevchenko
2022-07-07 17:36 ` Bram Cohen
2022-07-07 17:52   ` Pavol Rusnak
2022-07-07 17:58     ` Anton Shevchenko
2022-07-08  1:47     ` Bram Cohen
2022-07-08  2:19       ` Eric Voskuil
2022-07-08  4:35         ` vjudeu
2022-07-08  9:12           ` Paul Sztorc
2022-07-08 14:08             ` James MacWhyte
2022-07-09 20:31               ` Zac Greenwood [this message]
2022-07-09 22:21                 ` James MacWhyte
2022-07-09 23:46                 ` Anton Shevchenko
2022-07-11 13:11                   ` Erik Aronesty
2022-07-11 13:18                     ` Erik Aronesty

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