Bitcoin Core Introduces Privacy Fix in Version 32.x While Version 31.x Patch Awaits

Bitcoin Core has successfully merged a privacy fix into its 32.x source branch, which addresses the potential correlation between private-broadcast connections and regular node connections. As of October 8, the backport for version 31.x is still open, leaving users of the latest stable release, version 31.1, waiting for the necessary repairs.

The private broadcast feature, which is disabled by default, was initially modified in a backport released on October 1. This change had reached the main development branch on September 25. A separate proposal to apply the fix to version 31.x received approval from reviewer vasild on October 6, but it does not yet have a defined release date.

Users who opt for the private broadcast option utilize the sendrawtransaction command to send raw transactions to the network. This process employs short-lived connections to Tor or I2P peers, or to IPv4 and IPv6 peers via Tor. The correlation issue specifically pertains to this private-broadcast activity rather than all nodes operating under default settings.

The problem arises from Bitcoin Core’s handling of misbehaving peers, which could inadvertently link private-broadcast peers to ordinary node activity. The recent patch aims to separate these behaviors, ensuring that discouraging a private-broadcast peer does not affect other connections to the same peer address.

Earlier versions of Bitcoin Core had already addressed an IP-address leak issue, where private-broadcast connections could mistakenly use clearnet instead of the intended privacy network. The latest changes focus on observable effects of peer handling and have narrowed the privacy claims associated with private broadcast to risk reduction.

For users still on the older branch, the next steps involve awaiting the completion of the 31.x backport and the subsequent release that will include it.