nimbus-eth2/docs/nbc_audit_2020/eth2_spec_core/state_transition_logic.md

title	code_owner	round	category	repositories
State transition logic	(tersec)	Audit round 2	ETH2 Specification Core Audit	nim-beacon-chain

Spec: https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/beacon-chain.md#beacon-chain-state-transition-function

Annotated spec from Vitalik: https://github.com/ethereum/annotated-spec/blob/master/phase0/beacon-chain.md Annotated spec from Ben (from Consensys): https://benjaminion.xyz/eth2-annotated-spec/phase0/beacon-chain

Visual depiction: https://github.com/protolambda/eth2-docs#phase-0-beaconstate-transition

Implementation:

• block: https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/spec/state_transition_block.nim
• epoch: https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/spec/state_transition_epoch.nim
• High-level API: https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/spec/state_transition.nim and https://github.com/status-im/nim-beacon-chain/blob/master/beacon_chain/spec/state_transition_helpers.nim Implementation follows the spec closely with an additional caching mechanism that avoids recomputing epoch invariants.

Tests:

• Ethereum Foundation vectors are loaded here: https://github.com/status-im/nim-beacon-chain/tree/master/tests/official
• Self-tests were added for attestations, deposits and justification/finalization
  • https://github.com/status-im/nim-beacon-chain/tree/master/tests/spec_block_processing
  • https://github.com/status-im/nim-beacon-chain/tree/master/tests/spec_epoch_processing

Fuzzing via https://github.com/sigp/beacon-fuzz covers:

• attestation
• attester_slashing
• state transition for block
• deposit
• proposer slashing
• shuffling
• voluntary exit