BIP351 Private Payments Support

Private Payments (BIP351) is a stealth address system for Bitcoin that allows the user to post a static code and receive payments to a separate address space for each sender.

There are multiple use cases for Private Payments, but the static donation code seems to be the most compelling. A user wishing so solicit donations from the public may safely associate a payment code with her identity and receive funds in a relatively private manner.

The user story is similar to BIP47:

• Receiver posts their payment code
• Sender creates a notification payload and either posts it to the chain as an OP_RETURN or to some other bulletin board system
• Receiver scans the chain for these notification payloads and upon finding one, generates the chain of stealth addresses

Improvements over BIP47:

• Supports multiple address types
• Better notification payload privacy
• Smaller notification payloads

For more context, check out privatepayments.org and the Rust reference implementation.

Read BIP351 and the linked Rust reference implementation first, then compare their requirements with Electrum's existing BIP47 support. The issue names no Electrum files or tests, so the work is not yet localized; done would mean defining and implementing BIP351 wallet support, including notification handling and stealth address generation.