Armored Witness log should use tlog-tiles (via Tessera) #362
Description
The Firmware Transparency log used for the Armored Witness uses the serverless-log implementation. This log format has been obsoleted in favour of https://c2sp.org/tlog-tiles, which is supported by Tessera.
The proposal here is ambitious and risky: move the AW FT solution from the old serverless-log implementation over to a tlog-tiles API backed by Tessera. Probably using the POSIX driver.
The benefits of this end-state are:
- less cognitive overhead when working with the AW ecosystem (assuming you already understand tlog-tiles)
- benefit from tooling that builds on tlog-tiles (e.g. verifiable index)
- direct experience running a production log on Tessera
- removes a blocker to deprecating serverless-log
- this AW FT solution remains a canonical example of how to deploy end-to-end transparency that requires fewer caveats (i.e. do $this, but use a different log technology and API format)
We'll need to carefully consider steps to get from here to there, because any false steps could brick the AW devices and leave us with no path to update them.