Distributing binary blobs across organizational boundaries — such as between internal and open-source repositories or from a developer to the public — requires establishing trust and mitigating security risks. Binary transparency refers to the collective efforts to create this trust, ensuring that a binary has not been tampered with. This challenge is particularly relevant at Google, where binaries from open-source environments are untrusted in the corporate network, and conversely, corporate binaries are untrusted by the public.
We propose a general concept for binary transparency based on signed endorsements. An endorsement is an in-toto statement that contains a time-limited validity and falsifiable claims about a binary’s properties. The endorsement is signed by the developer. This signature is then immutably recorded in Rekor, a public transparency log. To be effective, the claims within an endorsement should be falsifiable, meaning there is a clear process to empirically disprove them.
While this concept is broadly applicable, practical implementations must be tailored to specific use cases, as requirements for file management, signing, and publishing differ significantly. We have developed one such implementation, designed to manage the boundary between open-source and internal repositories at Google.
Speaker
Tom Binder is a software engineer with Google Deepmind’s Oak team, specializing in the field of digital trust. He builds tools that establish binary transparency, bridging the gap between Google’s internal environment and the open-source world. His focus also includes attestation verification to prove that binaries are secure and untampered.
