Subject: Re: [bitcoindev] BIP39 Extension for Manual Seed Phrase Creation

From: "'Russell O'Connor' via Bitcoin Development Mailing List" <[email-masked]>
Date: Fri, 23 May 2025 16:45:22 -0400

FWIW, BIP-93 (codex32) was designed for both human and computer generated
randomness.  Codex32 also supports human and computer generated secret
sharing.

See also <https://secretcodex32.com/>.

On Fri, May 23, 2025 at 11:35 AM Eric <[email-masked]> wrote:

> Quoting BIP39: "This guide is meant to be a way to transport
> computer-generated randomness with a human-readable transcription."
>
> BIP39 was meant to capture computer generated randomness.  Manually
> calculating the sha256 hash is not practical.
>
> Using a separate tool to compute the checksum or last word is cumbersome
> and requires users to have a more advanced understanding of cryptography.
>
>
> On May 23, 2025 8:29:27 AM MDT, Kyle Honeycutt <[email-masked]>
> wrote:
>
>> Respectfully, a "black box" is not trusted to generate mnemonic
>> passphrases, the standard is well-defined and generally followed across
>> wallets.
>>
>>
>> https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki#Generating_the_mnemonic
>>
>> Users can create their own mnemonics in a trustless way following the
>> BIP39 standard published in 2013.
>>
>> Using any entropy source a user can perform a SHA256 hash on the entropy
>> to get a 256 bit string, then convert that to binary. Perform another
>> SHA256 hash on the binary, take the first 8 bits and solve for checksum and
>> then solve the rest of mnemonic words.
>>
>> On Fri, May 23, 2025, 6:15 AM Eric Kvam <[email-masked]> wrote:
>>
>>> *Motivation*
>>> Make it easy for users to manually create their seed phrase so that they
>>> don't have to trust a "black box" and allow for encoding derivation path in
>>> seed phrase to simplify recovery
>>>
>>> *How*
>>> Use every eighth word from the wordlist to generate 16 word phrases with
>>> 128 bits of entropy (no checksum).  The most significant eight bits of each
>>> word are used as entropy.  The least significant three bits of each word
>>> specify the derivation path.
>>>
>>>    - *000* Derivation Path Not Specified
>>>    - *001* m/44'/0'/0'
>>>    - *010* m/49'/0'/0'
>>>    - *011* m/84'/0'/0'
>>>    - *100* m/48'/0'/0'/2'
>>>    - *101* m/86'/0'/0'
>>>
>>> Up to seven derivation paths can be specified if all words have the same
>>> least significant bits.  If the least significant bits of each word vary,
>>> there are 48 bits that can be used to encode meta-data.  As long as
>>> meta-data is limited to certain allowable values, this provides a mechanism
>>> for error detection, similar to a checksum.
>>>
>>> *Benefits of Suggested Implementation*
>>>
>>>    - The word length determines how the seed phrase should be
>>>    interpreted.  User only needs to know how many words they have and how many
>>>    words the wallet supports to check for compatibility with this extension
>>>    - Uses same wordlist to represent the same entropy as a 12 word
>>>    phrase (could be a revision to BIP39 instead of a new BIP)
>>>    - Manual procedure is very simple, each derivation path can use a
>>>    shortened 256 word list which enjoys improved alphabetical separation of
>>>    words
>>>    - May prevent naive word selections which aren't limited to every
>>>    eighth word (similar to what checksum does)
>>>    - Can be extended further.  For example, a 32 word phrase with the
>>>    same entropy as a 24 word phrase could also be added.  We can keep adding
>>>    formats with unique word length and keep adding uses for the meta data as
>>>    needed.
>>>
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>>> .
>>>
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