From: James MacWhyte <macwhyte@gmail•com>
To: Zac Greenwood <zachgrw@gmail•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] No Order Mnemonic
Date: Sun, 10 Jul 2022 00:21:16 +0200 [thread overview]
Message-ID: <CAH+Axy7bgRgHKZD4hsfVsnUrNooa2kvxwNUhzycmG-MahAgnUQ@mail.gmail.com> (raw)
In-Reply-To: <CAJ4-pEA7WJpbExcsgdPWVNuZLrbDDhVYr37g6_6NSf7t41eB4w@mail.gmail.com>
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Thanks, Zac!
I indeed did get the napkin math very wrong. I now get around 10^30 total
possible phrases, which would take an impossibly long time to brute force.
So, it is less entropy but probably still sufficient for low-stakes usage.
James
On Sat, Jul 9, 2022 at 10:31 PM Zac Greenwood <zachgrw@gmail•com> wrote:
> 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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next prev parent reply other threads:[~2022-07-09 22:21 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-07 14:33 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
2022-07-09 22:21 ` James MacWhyte [this message]
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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