Proposal discussion: BIP39 native-language display wordlists

Ambiguity in handling mnemonic wordlists in multi-language contexts poses significant challenges that need careful consideration, particularly when differentiating between legacy and modern mnemonic systems. The proposal under discussion involves the reinterpretation of existing BIP39 wordlists to accommodate localized TZUR display mnemonics. This system maintains a separation where the localized words are used for user-facing interactions but do not directly influence the seed derivation process, which strictly uses the canonical English BIP39 mnemonic.

In practice, the derivation path for a TZUR display mnemonic follows a structured sequence: starting from localized TZUR display words, moving to word indices, then to canonical English BIP39 words, followed by standard BIP39 checksum validation, and culminating in standard PBKDF2 and BIP32/BIP84 derivation processes. This method ensures that the original, English mnemonic remains the core component in the cryptographic process, thereby preserving security and integrity across different language implementations.

The differentiation between legacy French BIP39 mnemonics and TZUR French display mnemonics exemplifies the necessity for clarity in wallet implementations. These two systems, although using the same human language, represent distinct encodings and should not be confused or treated as interchangeable. To prevent ambiguity, wallets should explicitly identify the wordlist mode being used—whether it is the legacy BIP39 French wordlist, the TZUR French display wordlist, or the canonical English BIP39. This identification can be facilitated by stable wordlist identifiers such as language code, version, and SHA256 hash of the wordlist file. Storing this metadata alongside the wallet data allows for accurate restoration and enhances portability.

To further enhance user experience without compromising security, it is recommended that wallets always display the canonical English mnemonic as the universal recovery form. This approach prevents automatic detection errors between legacy non-English BIP39 and TZUR display lists and maintains the English mnemonic as a reliable fallback during recovery operations. This strategy not only addresses the concerns raised about ambiguity but also aligns with best practices for cryptographic security and user interface design in digital wallet software.