A decade-old Bitcoin privacy proposal finally has resilient infrastructure.
BIP-47 allows for reusable payment codes, letting you receive payments to different addresses without revealing your identity. Its Achilles' heel was a centralized directory for discovering peers. The arrest of the Samurai Wallet team exposed the risk. Max Tannahill, on Ungovernable Misfits, explained the solution: a complete on-chain database. Using inscriptions in Bitcoin's witness space, BIP47DB.org turns the directory into an append-only, immutable protocol feature.
"This is moving the PayNIM directory onto the blockchain. It becomes a protocol-level feature, not a centralized service."
- Max Tannahill, Ungovernable Misfits
The Ashigaru team has already inscribed roughly 20,000 existing payment codes onto the mainnet. The total cost to secure the entire directory at current fee rates was about $150.
The database solves a major recovery problem. With a centralized server, if you restored your wallet from a seed phrase, you could see incoming payments but lose your connection history. The on-chain index allows wallets to scan a single Bitcoin address to find every registered payment code and notification address locally. This eliminates what Tannahill calls the 'metadata crutch,' enabling wallets like BlueWallet to support BIP 47 without interacting with a central server.
In a long-term vision, this infrastructure could eliminate the need for a 'notification transaction.' If every payment code is indexed on-chain, wallets could scan new blocks for potential payments directly, similar to silent payments, shifting the burden from the sender to the receiver scanning a decentralized list. This is a foundational upgrade, hardening Bitcoin's privacy stack against state interference.
