There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.1.1-alpha from the usual place on the website. Packages should be available over the coming weeks, with a new alpha Tor Browser release in the next couple of weeks.

Remember, this is an alpha release: you should only run this if you'd like to find and report more bugs than usual.

This is the first alpha in the 0.4.1.x series. It introduces lightweight circuit padding to make some onion-service circuits harder to distinguish, includes a new "authenticated SENDME" feature to make certain denial-of-service attacks more difficult, and improves performance in several areas.

Changes in version 0.4.1.1-alpha - 2019-05-22

Major features (circuit padding): Onion service clients now add padding cells at the start of their INTRODUCE and RENDEZVOUS circuits, to make those circuits' traffic look more like general purpose Exit traffic. The overhead for this is 2 extra cells in each direction for RENDEZVOUS circuits, and 1 extra upstream cell and 10 downstream cells for INTRODUCE circuits. This feature is only enabled when also supported by the circuit's middle node. (Clients may specify fixed middle nodes with the MiddleNodes option, and may force-disable this feature with the CircuitPadding torrc.) Closes ticket 28634.

Major features (code organization): Tor now includes a generic publish-subscribe message-passing subsystem that we can use to organize intermodule dependencies. We hope to use this to reduce dependencies between modules that don't need to be related, and to generally simplify our codebase. Closes ticket 28226.

