Witnessing Google's Transparency Logs

What is this?

This site is the home of Google's transparency log witness programme: the witnesses that cosign checkpoints for Google-operated transparency logs, and the configuration that log operators and verifiers use to interoperate with them.

Witnesses taking part make a service availability commitment to Google. The availability of Google's transparency logs depends on these cosignatures, so participation means undertaking to meet an agreed level of service, rather than cosigning on a best-effort basis.

The canonical source of truth is the google-tlog-witness GitHub repository, which contains:

• Log lists — the Google-operated transparency log origins that participating witnesses cosign, following the log-list format.
• Witness configurations — endpoints and keys for witnesses that cosign Google's log checkpoints, following the tlog-policy format.
• tlog-policy files — generated policy files consumed by log operators and verifiers.

Relationship to the Public Witness Network

The log list published here is not an open invitation to begin cosigning Google's logs, and membership of the Public Witness Network does not make a witness eligible for this programme. Witnesses are onboarded only by agreement with Google, given the availability commitment described above.

Equally, this is not a route into the Public Witness Network. If you would like to witness transparency logs on a best-effort, community basis, then participate there directly.

Log list

The combined log list for participating witnesses is available at:
log-list-10qps-10klogs.txt

The name states the service envelope the list is bounded by: at most 10,000 logs, which together may send at most 10 cosignature requests per second to a witness.

This file is rebuilt from the repo on every commit to main and follows the witness-network log-list format.

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Getting involved

Witness operators join this programme by agreement with Google, rather than by open enrolment. If you operate a witness and are interested in taking part, please open an issue to start the conversation.

Once an agreement is in place, endpoints and keys are managed in the repository: create or edit your file under witnesses/ and submit a pull request for review. See the README for details on the witness file format.