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) as an application of
BIP-0085 (Deterministic Entropy from BIP32 Keychains), 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 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

Feedback is welcome.

Best regards,
Ben Westgate