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Transparency Log

Last modified: Feb 9th, 2026

A transparency log is a cryptographically-secured append-only log, implemented using merkle trees. The most widely used version of this is the Certificate Transparency program.

These kinds of logs are established through shared APIs, an RFC, and support from Google. The software for them is high quality. I don’t know yet how tunable it is, for example how easy it is to extract data or hide it.

Also known as:

• Tamper-evident log
• Verifiable log
• Transparent log

Research links:

• https://github.com/google/trillian
• https://github.com/google/trillian/blob/master/docs/papers/VerifiableDataStructures.pdf
• https://transparency.dev/
  • https://transparency.dev/verifiable-data-structures/
  • https://transparency.dev/articles/tile-based-logs/
• https://research.swtch.com/tlog
• https://go.dev/blog/module-mirror-launch
• https://github.com/C2SP/C2SP/blob/main/tlog-tiles.md
• https://github.com/transparency-dev/tessera