The weakest link in Bitcoin’s privacy infrastructure was a single server. When Samourai Wallet fell to regulators in 2024, its PayNym directory - a lookup table for reusable payment codes - could have gone dark. Wallets that relied on it for metadata would have lost the ability to recover transaction histories.
Max Tannahill built BIP47DB.org to remove that central point of failure. The protocol uses Ordinals inscriptions to compress and publish payment codes directly on the Bitcoin blockchain. This creates an immutable, append-only database that any wallet can scan locally to rebuild a directory of peers. Tannahill argues on-chain storage is the only way to ensure resilience against state interference.
The Ashigaru team, which maintained Samourai’s codebase after its legal issues, has already inscribed approximately 20,000 existing payment codes. At current fee rates, securing the entire directory cost only about $150.
"Moving this data onto the blockchain is the only way to ensure resilience against state interference."
- Max Tannahill, Ungovernable Misfits
The database solves a critical recovery gap. BIP47 lets users share a single payment code for repeated private payments. Restoring a wallet from a seed phrase shows incoming payments but often loses the history of connections the user initiated. Centralized servers like PayNym filled this gap by acting as a lookup table for notification transactions.
Tannahill’s on-chain index allows wallets to scan a specific 'numbers address' to find every registered payment code locally. This removes what he calls the 'metadata crutch.' Wallets like BlueWallet could support BIP47 without ever querying a central server.
The long-term vision is more radical. If every payment code is indexed on-chain, the 'notification transaction' could become obsolete. Receivers could scan new blocks for potential payments, similar to silent payments. This would shift the burden from the sender making a public announcement to the receiver consulting a decentralized list.
BIP47DB is designed as backend infrastructure for wallet and directory operators, not for direct retail use. The goal is to let the ecosystem survive the loss of any single PayNym server.
Six weeks after Bitcoin Core v31 shipped with new privacy hardening features, this move targets a different layer of the stack. Where ASMAP defends nodes from network-level attacks, BIP47DB defends payment metadata from application-level seizure.
