A Framework for Securing Software Update Systems

The Update Framework (TUF) is a framework for secure content delivery and updates. It protects against various types of supply chain attacks and provides resilience to compromise. This repository is a reference implementation written in Python. It is intended to conform to version 1.0 of the TUF specification.

Python-TUF provides two APIs:

• tuf.api.metadata, a "low-level" API, designed to provide easy and safe access to TUF metadata and to handle (de)serialization from/to files.
• tuf.ngclient, a client implementation built on top of the metadata API.

High-level support for implementing repository operations is planned but not yet provided: see ADR 10.

The reference implementation strives to be a readable guide and demonstration for those working on implementing TUF in their own languages, environments, or update systems.

About The Update Framework

The Update Framework (TUF) design helps developers maintain the security of a software update system, even against attackers that compromise the repository or signing keys. TUF provides a flexible specification defining functionality that developers can use in any software update system or re-implement to fit their needs.

TUF is hosted by the Linux Foundation as part of the Cloud Native Computing Foundation (CNCF) and its design is used in production by various tech companies and open source organizations. A variant of TUF called Uptane is used to secure over-the-air updates in automobiles.

Please see TUF's website for more information about TUF!

Documentation

• Introduction to TUF's Design
• The TUF Specification
• Developer documentation, including API reference
• Usage examples
• Governance and Maintainers for the reference implementation
• Miscellaneous Docs
• Python-TUF development blog

Contact

Questions, feedback, and suggestions are welcomed on our low volume mailing list or the #tuf channel on CNCF Slack.

We strive to make the specification easy to implement, so if you come across any inconsistencies or experience any difficulty, do let us know by sending an email, or by reporting an issue in the GitHub specification repo.

Security Issues and Bugs

Security issues can be reported by emailing [email protected].

At a minimum, the report must contain the following:

• Description of the vulnerability.
• Steps to reproduce the issue.

Optionally, reports that are emailed can be encrypted with PGP. You should use PGP key fingerprint E9C0 59EC 0D32 64FA B35F 94AD 465B F9F6 F8EB 475A.

Please do not use the GitHub issue tracker to submit vulnerability reports. The issue tracker is intended for bug reports and to make feature requests. Major feature requests, such as design changes to the specification, should be proposed via a TUF Augmentation Proposal (TAP).

Limitations

The reference implementation may behave unexpectedly when concurrently downloading the same target files with the same TUF client.

License

This work is dual-licensed and distributed under the (1) MIT License and (2) Apache License, Version 2.0. Please see LICENSE-MIT and LICENSE.

Acknowledgements

This project is hosted by the Linux Foundation under the Cloud Native Computing Foundation. TUF's early development was managed by members of the Secure Systems Lab at New York University. We appreciate the efforts of all maintainers and emeritus maintainers, as well as the contributors Konstantin Andrianov, Kairo de Araujo, Ivana Atanasova, Geremy Condra, Zane Fisher, Pankhuri Goyal, Justin Samuel, Tian Tian, Martin Vrachev and Yuyu Zheng who are among those who helped significantly with TUF's reference implementation. Maintainers and Contributors are governed by the CNCF Community Code of Conduct.

This material is based upon work supported by the National Science Foundation under Grant Nos. CNS-1345049 and CNS-0959138. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.