Proposal: Self-Verifiable Transaction Broadcast Log for Enhanced User Transparency

Liang suggests the creation of a Self-Verifiable Transaction Broadcast Log, an opt-in feature that would record all transactions a node accepts for broadcast, complete with timestamps and source information. This mechanism could include filtering options by address or wallet and introduce a new RPC call (getbroadcastedtxs) to facilitate access to these records. The purpose behind this proposal is to enable users and wallets to verify the existence of transactions that may have been dropped, reorganized, or not confirmed, without altering any consensus behavior. The log would be locally manageable, allowing users to purge it as they see fit.

Liang's motivation for this proposal stems from personal experience, where a valid transaction was made but later could not be located in the mempool, the blockchain, nor through block explorers, despite having the private key. This scenario highlights potential risks like transaction censorship or selective orphaning by powerful entities without leaving verifiable traces for users. Such a feature aims to enhance transparency and auditability for users, particularly those focused on privacy or using air-gapped setups who do not maintain comprehensive mempool logs.

In seeking feedback from the Bitcoin development community, Liang raises several points for consideration, including the value of such a feature for user transparency, potential concerns regarding wallet behavior and privacy, suggestions on whether the logs should be stored in-memory or on disk by default, and if wallet software would benefit from incorporating this feature for user access. The proposal has been drafted preliminarily as a Bitcoin Improvement Proposal (BIP) and Liang invites early feedback before moving forward with a formal PR or implementation patch, expressing readiness to follow up with a reference implementation for Bitcoin Core compatible with version 25 and above.