BIP352 private key formats

The discussion focuses on enhancing the Bitcoin Improvement Proposal (BIP) by suggesting modifications to how labels and per-transaction (per-tx) information are handled during wallet imports. The conversation underscores the importance of including a block number, referred to as the "birthday," for both labels and per-tx data. This addition aims to inform the wallet that it is unnecessary to verify transactions prior to this block, streamlining the restoration process.

For per-tx information, the BIP already mandates a scan action upon import. Incorporating a birthday indicates to the wallet that it should commence scanning from a specified block, thereby optimizing the restoration procedure by eliminating the need to check transactions before this block. This approach assumes the wallet will initiate a scan upon import, aligning with current BIP stipulations.

Regarding labels, the proposal suggests encoding them as an array at the end of the transaction data. This method would allow for efficient organization and retrieval of label information. Even in cases where no label is explicitly provided, the system should default to checking the “0” (change) label, ensuring consistency across transactions. If a wallet restores from BIP39, the latest block at the time of the BIP's publication should be designated as the birthday. Under this scenario, the only required label would be the change label “0,” simplifying the restoration process for users.

These proposed enhancements aim to refine the wallet import process by introducing a structured approach to handling labels and per-tx information, potentially improving user experience and wallet functionality. The idea of submitting a Pull Request (PR) to modify the BIP reflects an active engagement with the community to update and improve the protocol based on practical considerations and technical insights.