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

Liang proposes the introduction of a Self-Verifiable Transaction Broadcast Log, which aims to serve as an opt-in feature allowing nodes to record all accepted transactions for broadcast, inclusive of timestamps and source details. This proposed feature is designed to assist users and wallets in verifying transactions that may have been dropped, reorganized, or failed to confirm, without impacting consensus behavior. The log, according to Liang, would be equipped with filtering capabilities and accessible through a new RPC call (getbroadcastedtxs), enabling users to manage it according to their needs.

Liang's motivation for this proposal is rooted in personal experience, highlighting a situation where a valid transaction could not be located within the mempool, blockchain, or via block explorers, despite having access to the private key involved. This incident raises concerns over potential censorship or selective orphaning by influential entities, which could occur without leaving any verifiable traces for users. By introducing this logging feature, the proposal seeks to bolster transparency and auditability, particularly benefiting users concerned with privacy or those utilizing air-gapped setups who lack comprehensive mempool logs.

In soliciting feedback from the Bitcoin development community, Liang presents several considerations associated with the proposal. These include evaluating the feature's value in enhancing user transparency, addressing potential wallet behavior and privacy issues, determining whether the logs should be stored in-memory or on disk by default, and assessing the benefit of integrating this feature into wallet software for easier user access. Initially drafted as a Bitcoin Improvement Proposal (BIP), Liang invites preliminary feedback before proceeding with a formal PR or implementation patch, indicating readiness to contribute a reference implementation compatible with Bitcoin Core version 25 and above. For further discussion, Liang suggests engaging on platforms like Bitcoin StackExchange, recognizing that the topic may extend beyond the scope of the initial mailing list discussion.