BIP39 native-language display wordlists mapped to canonical English

Daniel has proposed an enhancement to the BIP39 recovery phrase mechanism aimed at improving user experience for non-English speakers. This proposal introduces a native-language display and input layer that utilizes wordlists in the user's native language while maintaining the English BIP39 mnemonic as the canonical form. The essence of this proposal is to use localized words purely as a deterministic overlay for display and input purposes. These words would correspond to fixed indexes, which then map back to the canonical English words used in the validation and derivation processes inherent to the BIP39 standard.

The motivation behind this initiative stems from the practical challenges faced by users who must use English recovery phrases, even when they are not proficient in English. This often leads to errors and insecurities during the backup and recovery phases. By allowing the display and entry of recovery phrases in a user's native language, the proposal aims to reduce these barriers, making the process more accessible and less prone to mistakes.

However, the proposal also emphasizes the importance of maintaining strict compatibility with the existing English-based BIP39 system. Wallets implementing this feature would treat any local language lists as separate layers, not as replacements or alternate mnemonic systems. This approach ensures that the core cryptographic processes remain unchanged and that any local language implementation strictly adheres to the established BIP39 protocols. Concerns have been raised regarding potential ambiguities, such as the risk of misinterpreting a user-entered phrase in a local language as a different type of mnemonic. To address this, Daniel suggests that wallets should clearly differentiate between legacy and new display mnemonics through explicit user interface cues and robust import/export behaviors.

Daniel has shared this early-stage proposal on the Bitcoin Development mailing list for broader discussion and has made draft implementations and wordlists available for review. He seeks feedback particularly on any hidden risks this index-mapped display-layer model might introduce and whether the method of explicit mode selection effectively mitigates confusion with existing non-English BIP39 wordlists. His posting aims to garner deeper technical insights before determining whether to keep this as a wallet-level convention or evolve it into a formal informational BIP. Feedback from the community will be crucial in refining and validating the feasibility and safety of this proposed enhancement.