Subject: [bitcoindev] Re: [BIP Proposal] Add BIP-0093 (Codex32) as application to BIP-0085

From: Javier Mateos <[email-masked]>
Date: Mon, 1 Sep 2025 19:30:42 -0700 (PDT)

Hi Ben,

Thank you for implementing those changes so promptly. I reviewed the commit 
and the updates address both concerns effectively.

These changes should ensure consistent implementations across different 
codex32 tooling that uses BIP-85 derivation.

The proposal looks technically sound, follows BIP-85's established pattern 
for applications, and is supported by comprehensive test vectors and a 
reference implementation. 

Looking forward to hearing feedback from other reviewers as well.

Best regards,
Javier Mateos

El lunes, 1 de septiembre de 2025 a las 20:15:11 UTC-3, Ben Westgate 
escribió:

> Hi Javier,
>
> Thank you for your feedback. 
>
> I added pseudocode for the character value selection. I added a column and 
> row to the n table to clarify the t==0 constraint on n, removed the notes 
> and in the unshared secret section made the normative statement: 'When threshold 
> == "0", n MUST be *1* and the output is a codex32 secret.'
>
> I’ve updated the PR with these changes and would appreciate your review.
>
> Commit: 
> https://github.com/BenWestgate/bips/commit/fa6e9788bf04d271792ed4ea89a112d12284ef02
>
> Best regards, Ben Westgate
>
>
> On Monday, September 1, 2025 at 6:34:39 AM UTC-5 Javier Mateos wrote:
>
>> Hi Ben,
>>
>> Thank you for your proposal to integrate BIP-0093 (codex32) as an 
>> application within BIP-0085
>>
>> Reviewing the specification,  I believe I see two areas where we could 
>> improve clarity for implementers:
>>
>> 1) The DRNG→5-bit extraction process could benefit from explicit 
>> pseudocode to avoid implementation variations
>> 2) The rule 'threshold == 0 implies n == 1' currently appears as a note 
>> but could be clearer as a normative requirement"
>>
>> Best Regards,
>> Javier Mateos
>>
>> El domingo, 31 de agosto de 2025 a las 19:29:46 UTC-3, Ben Westgate 
>> escribió:
>>
>>> Hello bitcoin-dev,
>>>
>>> I’m Ben Westgate, a contributor interested in deterministic wallet 
>>> backups and seed management.
>>>
>>> Per BIP-0002, I propose listing *BIP-0093 (codex32)* 
>>> <https://github.com/bitcoin/bips/blob/master/bip-0093.mediawiki> as an 
>>> application of
>>> *BIP-0085 (Deterministic Entropy from BIP32 Keychains) 
>>> <https://github.com/bitcoin/bips/blob/master/bip-0085.mediawiki>*, 
>>> similar to the existing BIP39 application. This allows wallets to derive 
>>> codex32 backups from BIP-0032 master keys.
>>>
>>> *Summary* 
>>>
>>>    - 
>>>    
>>>    Application number: 93'
>>>    - Derivation path: 
>>>    m/83696968'/93'/{hrp}'/{threshold}'/{n}'/{byte_length}'/{id0}'/{id1}'/{id2}'/{id3}'/{index}' 
>>>    
>>> Codex32, defined in BIP-93, is a human-readable encoding with 
>>> checksumming and share indexing designed for SSS backups of BIP-0032 seeds. 
>>> This PR proposes a deterministic way to generate codex32 strings using 
>>> BIP-85.
>>>
>>> *Rationale* 
>>>
>>>    - 
>>>    
>>>    Mirrors the existing BIP-85 application for BIP-39.
>>>    - 
>>>    
>>>    Codex32 offers error correction, hand verification, identifiers, and 
>>>    secret sharing features compared to BIP-39.
>>>    - 
>>>    
>>>    Adds a standardized way for wallets to generate codex32 backups from 
>>>    BIP-85-derived entropy
>>>    - 
>>>    
>>>    Test vectors and reference implementation are linked to in the PR.
>>>    
>>> *Risks and alternatives* 
>>>
>>>    - 
>>>    
>>>    Wallet adoption of codex32 is still limited, though a draft PR #32652 
>>>    <https://github.com/bitcoin/bitcoin/pull/32652?utm_source=chatgpt.com> 
>>>    for importing codex32 strings to Bitcoin Core has support.
>>>    - Codex32 implementers could use the BIP-85 dice application, but 
>>>    defining a direct application improves interoperability.
>>>
>>> PR: 
>>> https://github.com/bitcoin/bips/compare/master...BenWestgate:bips:codex32 
>>> <https://github.com/bitcoin/bips/compare/master...BenWestgate:bips:codex32?utm_source=chatgpt.com>
>>>
>>> Feedback is welcome.
>>> Best regards,
>>> Ben Westgate
>>
>>

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