A Framework for Securing Software Update Systems

This repository is the reference implementation of The Update Framework (TUF). It is written in Python and intended to conform to version 1.0 of the TUF specification.

The repository currently includes two implementations:

1. A legacy implementation, with tuf/client/updater.py implementing the detailed client workflow and tuf/repository_tool.py providing a high-level interface for repository operations. The legacy implementation is in use in production systems, but is no longer being actively worked on.
2. A modern implementation. We are in the process of rewriting the reference implementation in modern Python to both: a) address scalability and integration issues identified in supporting integration into the Python Package Index (PyPI), and other large-scale repositories, and b) to ensure maintainability of the project. This implementation consists of:
   • a "low-level" metadata API, designed to provide easy and safe access to TUF metadata and handle (de)serialization from/to files, provided in the tuf/api/metadata.py module.
   • an implementation of the detailed client workflow built on top of the metadata API, provided in the tuf/ngclient/updater.py module. The modern implementation is not considered production ready and does not yet provide any high-level support for implementing repository operations, though the addition of API to support them is planned.

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 the TUF Introduction and TUF's website for more information about TUF!

Documentation

• Introduction to TUF's Design
• The TUF Specification
• Getting Started with the TUF Reference Implementation
• Governance and Maintainers for the reference implementation
• Miscellaneous Docs

Contact

Please contact us via our mailing list. Questions, feedback, and suggestions are welcomed on this low volume mailing list.

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 jcappos@nyu.edu.

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 Konstantin Andrianov, Geremy Condra, Vladimir Diaz, Yuyu Zheng, Sebastien Awwad, Santiago Torres-Arias, Trishank Kuppusamy, Zane Fisher, Pankhuri Goyal, Tian Tian, Konstantin Andrianov, and Justin Samuel who are among those who helped significantly with TUF's reference implementation. Contributors and maintainers 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.