## Issue Addressed
Closes#2419
## Proposed Changes
Address a long-standing issue with the import of slashing protection data where the import would fail due to the data appearing slashable w.r.t the existing database. Importing is now idempotent, and will have no issues importing data that has been handed back and forth between different validator clients, or different implementations.
The implementation works by updating the high and low watermarks if they need updating, and not attempting to check if the input is slashable w.r.t itself or the database. This is a strengthening of the minification that we started to do by default since #2380, and what Teku has been doing since the beginning.
## Additional Info
The only feature we lose by doing this is the ability to do non-minified imports of clock drifted messages (cf. Prysm on Medalla). In theory, with the previous implementation we could import all the messages in case of clock drift and be aware of the "gap" between the real present time and the messages signed in the far future. _However_ for attestations this is close to useless, as the source epoch will advance as soon as justification occurs, which will require us to make slashable attestations with respect to our bogus attestation(s). E.g. if I sign an attestation 100=>200 when the current epoch is 101, then I won't be able to vote in any epochs prior to 101 becoming justified because 101=>102, 101=>103, etc are all surrounded by 100=>200. Seeing as signing attestations gets blocked almost immediately in this case regardless of our import behaviour, there's no point trying to handle it. For blocks the situation is more hopeful due to the lack of surrounds, but losing block proposals from validators who by definition can't attest doesn't seem like an issue (the other block proposers can pick up the slack).
## Issue Addressed
Closes#1873
## Proposed Changes
Fixes the bug in slashing protection import (#1873) by pruning the database upon import.
Also expands the test generator to cover this case and a few others which are under discussion here:
https://ethereum-magicians.org/t/eip-3076-validator-client-interchange-format-slashing-protection/4883
## Additional Info
Depending on the outcome of the discussion on Eth Magicians, we can either wait for consensus before merging, or merge our preferred solution and patch things later.
## Issue Addressed
Implements support for importing and exporting the slashing protection DB interchange format described here:
https://hackmd.io/@sproul/Bk0Y0qdGD
Also closes#1584
## Proposed Changes
* [x] Support for serializing and deserializing the format
* [x] Support for importing and exporting Lighthouse's database
* [x] CLI commands to invoke import and export
* [x] Export to minimal format (required when a minimal format has been previously imported)
* [x] Tests for export to minimal (utilising mixed importing and attestation signing?)
* [x] Tests for import/export of complete format, and import of minimal format
* [x] ~~Prevent attestations with sources less than our max source (Danny's suggestion). Required for the fake attestation that we put in for the minimal format to block attestations from source 0.~~
* [x] Add the concept of a "low watermark" for compatibility with the minimal format
Bonus!
* [x] A fix to a potentially nasty bug involving validators getting re-registered each time the validator client ran! Thankfully, the ordering of keys meant that the validator IDs used for attestations and blocks remained stable -- otherwise we could have had some slashings on our hands! 😱
* [x] Tests to confirm that this bug is indeed vanquished
* Implement slashing protection
Roll-up of #588 with some conflicts resolved
* WIP improvements
* Require slot uniqueness for blocks (rather than epochs)
* Native DB support for Slot and Epoch
* Simplify surrounding/surrounded-by queries
* Implement unified slashing protection database
A single SQL database saves on open file descriptors.
* Make slashing protection concurrency safe.
Revive tests, add parallel tests.
* Some simplifications
* Auto-registration, test clean-ups
* More tests, clean-ups, hardening
* Fix comments in BLS
* Optimise bulk validator registration
* Delete outdated tests
* Use bundled SQLite in slashing protection
* Auto-register validators in simulation
* Use real signing_root in slashing protection
* Update book for --auto-register
* Refine log messages and help flags
* Correct typo in Cargo.toml authors
* Fix merge conflicts
* Safer error handling in sqlite slot/epoch
* Address review comments
* Add attestation test mutating block root
Co-authored-by: pscott <scottpiriou@gmail.com>
