deterministic builds

Tor at the Reproducible Builds Workshop in Athens 2015

Being able to build Tor Browser several times in a row and getting exactly the same result each time has been an

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Tor Browser Bundle 3.0beta1 Released

The first beta release in the 3.0 series of the Tor Browser Bundle is now available from the Tor Package Archive:

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Deterministic Builds Part Two: Technical Details

This is the second post in a two-part series on the build security improvements in the Tor Browser Bundle 3.0 release cycle

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Tor Browser Bundle 3.0alpha4 Released

The third alpha release in the 3.0 series of the Tor Browser Bundle is now available from the Tor Package Archive:

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Deterministic Builds Part One: Cyberwar and Global Compromise

I've spent the past few months developing a new build system for the 3.0 series of the Tor Browser Bundle that produces

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Tor Browser Bundle 3.0alpha3 Released

The third alpha release in the 3.0 series of the Tor Browser Bundle is now available from the Tor Package Archive:

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Tor Browser Bundle 3.0alpha2 Released

The second alpha release in the 3.0 series of the Tor Browser Bundle is now available from the

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New Release: Tor Browser 10.5a11

Tor Browser 10.5a11 is now available from the Tor Browser Alpha download page and also from our

New Release: Tor Browser 10.0.12

Tor Browser 10.0.12 is now available from the Tor Browser download page and also from our

After months of work, we have a new stable release series! If you build Tor from source, you can download the source code for 0.4.5.6 on the download page. Packages should be available within the next several weeks, with a new Tor Browser likely next week.

The Tor 0.4.5.x release series is dedicated to the memory of Karsten Loesing (1979-2020), Tor developer, cypherpunk, husband, and father. Karsten is best known for creating the Tor metrics portal and leading the metrics team, but he was involved in Tor from the early days. For example, while he was still a student he invented and implemented the v2 onion service directory design, and he also served as an ambassador to the many German researchers working in the anonymity field. We loved him and respected him for his patience, his consistency, and his welcoming approach to growing our community.

This release series introduces significant improvements in relay IPv6 address discovery, a new "MetricsPort" mechanism for relay operators to measure performance, LTTng support, build system improvements to help when using Tor as a static library, and significant bugfixes related to Windows relay performance. It also includes numerous smaller features and bugfixes.

Below are the changes since 0.4.4.7. For a list of changes since 0.4.5.5-rc, see the ChangeLog file.

Changes in version 0.4.5.6 - 2021-02-15

Major features (build):
- When building Tor, first link all object files into a single static library. This may help with embedding Tor in other programs. Note that most Tor functions do not constitute a part of a stable or supported API: only those functions in tor_api.h should be used if embedding Tor. Closes ticket 40127.
Major features (metrics):
- Introduce a new MetricsPort which exposes, through an HTTP interface, a series of metrics that tor collects at runtime. At the moment, the only supported output format is Prometheus data model. Closes ticket 40063. See the manual page for more information and security considerations.