Quick Take
- Bitcoin Core merged the private-broadcast connection-linking repair into v32 code on October 1, while the v31 backport remains open.
- The repair isolates private-broadcast peer handling while still disconnecting misbehaving peers, reducing a specific route for correlating connections.
- The stable download remains 31.1, whose earlier clearnet IP-leak fix is separate from the newer connection-linking repair.
Bitcoin Core has merged a privacy fix into its 32.x source branch addressing behavior that could correlate private-broadcast connections with ordinary node connections. The backport for 31.x remains open as of Oct. 8, leaving users who enable the feature on the latest stable release, 31.1, awaiting the repair. Private broadcast is disabled by default.
The Oct. 1 backport includes the original change, which reached the main development branch on Sept. 25. The separate proposal to bring the fix to 31.x received an approval from reviewer vasild on Oct. 6 and carries a 31.2 milestone. That assignment does not establish a release date.
The official download page still lists 31.1 as the latest version. The 32.0 download directory contains test candidates rather than final-release files, including rc3 binaries dated Oct. 6.
The opt-in path at risk
Users enable the privatebroadcast option for submissions through sendrawtransaction, the command for sending a raw transaction to the network. That path uses dedicated, short-lived connections to Tor or I2P peers, or to IPv4 and IPv6 peers through Tor. The connection-linking concern applies to this private-broadcast activity, rather than every node running the default configuration.
The problem involves “discouragement,” Bitcoin Core’s handling of certain misbehaving peers, the other nodes it connects to. Reviewers of the original fix explained that discouraging a private-broadcast peer could alter node behavior visible from outside. Normal discouragement could also disconnect other connections to the same peer address. Those shared effects could provide an observer with a clue linking the private connection to ordinary node activity.
The patch separates those behaviors. Private-broadcast peers are excluded from normal discouragement handling, while misbehaving private peers are still disconnected. Conversely, discouraging an ordinary peer no longer disconnects private-broadcast connections sharing its address.
Bitcoin Core’s 31.1 release notes describe an earlier IP-address leak: under some circumstances, private-broadcast connections used clearnet instead of the enabled privacy network. That repair addressed how connections were routed. The newer change addresses observable effects of peer handling.
Developers also marked private broadcast experimental and narrowed its privacy claims to risk reduction. For users on the older branch, the next steps remain a completed 31.x backport and a release containing it.
Mentioned in this article
Editorial credits
