cryptography | Tor Blog

Technology in Hostile States: Ten Principles for User Protection

This blog post is meant to generate a conversation about best practices for using cryptography and privacy by design to improve security and protect user data from well-resourced attackers and oppr

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CryptoParty Stockholm

I attended the Stockholm Cryptoparty on Saturday the 16th of February.

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Recent Updates

Reaching People Where They Are

Part of the Tor Project's mission is to further the popular understanding of privacy technologies, and we believe we can achieve it by combining educational efforts with usability

We have a new stable release today. If you build Tor from source, you can download the source code for 0.4.1.6 from the download page on the website. Packages should be available within the next several weeks, with a new Tor Browser in the next week or two.

This release backports several bugfixes to improve stability and correctness. Anyone experiencing build problems or crashes with 0.4.1.5, or experiencing reliability issues with single onion services, should upgrade.

Changes in version 0.4.1.6 - 2019-09-19

Major bugfixes (crash, Linux, Android, backport from 0.4.2.1-alpha):
- Tolerate systems (including some Android installations) where madvise and MADV_DONTDUMP are available at build-time, but not at run time. Previously, these systems would notice a failed syscall and abort. Fixes bug 31570; bugfix on 0.4.1.1-alpha.
- Tolerate systems (including some Linux installations) where madvise and/or MADV_DONTFORK are available at build-time, but not at run time. Previously, these systems would notice a failed syscall and abort. Fixes bug 31696; bugfix on 0.4.1.1-alpha.
Minor features (stem tests, backport from 0.4.2.1-alpha):
- Change "make test-stem" so it only runs the stem tests that use tor. This change makes test-stem faster and more reliable. Closes ticket 31554.

New Release: Tor 0.4.2.1-alpha

There's a new alpha release available for download. If you build Tor from source, you can download the source code for 0.4.2.1-alpha from the download page 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 release in the 0.4.2.x series. It adds new defenses for denial-of-service attacks against onion services. It also includes numerous kinds of bugfixes and refactoring to help improve Tor's stability and ease of development.

Changes in version 0.4.2.1-alpha - 2019-09-17

Major features (onion service v3, denial of service):
- Add onion service introduction denial of service defenses. Intro points can now rate-limit client introduction requests, using parameters that can be sent by the service within the ESTABLISH_INTRO cell. If the cell extension for this is not used, the intro point will honor the consensus parameters. Closes ticket 30924.
Major bugfixes (circuit build, guard):
- When considering upgrading circuits from "waiting for guard" to "open", always ignore circuits that are marked for close. Previously we could end up in the situation where a subsystem is notified of a circuit opening, but the circuit is still marked for close, leading to undesirable behavior. Fixes bug 30871; bugfix on 0.3.0.1-alpha.

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