3.4 KiB
| title | code_owner | round | category | repositories |
|---|---|---|---|---|
| Slash Prevention Mechanisms | Mamy André-Ratsimbazafy (mratsim) | Audit round 3 | Validator Core Audit | nim-beacon-chain |
Note: Slashing Protection is a very new feature and not merged/enabled by default yet in the codebase.
For the moment it leaves in the PR: https://github.com/status-im/nim-beacon-chain/pull/1643
Resources
Overview of slashing and how it ties in with the rest of Eth2.0
Phase 0 for humans - Validator responsibilities:
Phase 0 spec - Honest Validator - how to avoid slashing
In-depth reading on slashing conditions
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Detecting slashing conditions https://hackmd.io/@n0ble/By897a5sH
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Open issue on writing a slashing detector https://github.com/ethereum/eth2.0-pm/issues/63
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Casper the Friendly Finality Gadget, Vitalik Buterin and Virgil Griffith https://arxiv.org/pdf/1710.09437.pdf Figure 2 An individual validator ν MUST NOT publish two distinct votes,〈ν,s1,t1,h(s1),h(t1) AND〈ν,s2,t2,h(s2),h(t2), such that either: I. h(t1) = h(t2). Equivalently, a validator MUST NOT publish two distinct votes for the same target height.
OR II. h(s1) < h(s2) < h(t2) < h(t1). Equivalently, a validator MUST NOT vote within the span of its other votes.
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Vitalik's annotated spec:
d8c51af84f/phase0/beacon-chain.md (proposerslashing)1. A proposer can get slashed for signing two distinct headers at the same slot. 2. An attester can get slashed for signing two attestations that together violate the Casper FFG slashing conditions. -
https://github.com/ethereum/eth2.0-specs/blob/v0.12.2/specs/phase0/validator.md#ffg-vote
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The "source" is the current_justified_epoch
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The "target" is the current_epoch
Reading on weak subjectivity
- https://notes.ethereum.org/@adiasg/weak-subjectvity-eth2
- https://www.symphonious.net/2019/11/27/exploring-ethereum-2-weak-subjectivity-period/
- https://ethresear.ch/t/weak-subjectivity-under-the-exit-queue-model/5187
Reading of interop serialization format
- Import/export format: https://hackmd.io/@sproul/Bk0Y0qdGD
- Tests: https://github.com/eth2-clients/slashing-protection-interchange-tests
Implementation
In validator_slashing_protection.nim (TODO merge PR and tag an audit branch)
and used in validator_duties.nim (no VC/BN split) or validator_clients.nim (with Validator Client/Beacon Node split)
For slashing protection (in contrast to slashing detection) we only care about our own validators. We also assume that before signing a block or an attestation, the node is "synced" to the chain, i.e. it knows last finalized epoch of the whole blockchain.
The isSynced function has a naive heuristic for now and will be changed in the future to properly handle weak subjectivity period.