import datatypes, digest, helpers {.push raises: [Defect].} const SAFETY_DECAY* = 10'u64 # https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/weak-subjectivity.md#calculating-the-weak-subjectivity-period func compute_weak_subjectivity_period*(state: BeaconState): uint64 = var weak_subjectivity_period = MIN_VALIDATOR_WITHDRAWABILITY_DELAY let validator_count = get_active_validator_indices_len(state, get_current_epoch(state)) if validator_count >= MIN_PER_EPOCH_CHURN_LIMIT * CHURN_LIMIT_QUOTIENT: weak_subjectivity_period += SAFETY_DECAY * CHURN_LIMIT_QUOTIENT div (2 * 100) else: weak_subjectivity_period += SAFETY_DECAY * validator_count div (2 * 100 * MIN_PER_EPOCH_CHURN_LIMIT) return weak_subjectivity_period # https://github.com/ethereum/eth2.0-specs/blob/v0.12.3/specs/phase0/weak-subjectivity.md#checking-for-stale-weak-subjectivity-checkpoint func is_within_weak_subjectivity_period*(current_slot: Slot, ws_state: BeaconState, ws_checkpoint: Checkpoint): bool = # Clients may choose to validate the input state against the input Weak Subjectivity Checkpoint doAssert ws_state.latest_block_header.state_root == ws_checkpoint.root doAssert compute_epoch_at_slot(ws_state.slot) == ws_checkpoint.epoch let ws_period = compute_weak_subjectivity_period(ws_state) ws_state_epoch = compute_epoch_at_slot(ws_state.slot) current_epoch = compute_epoch_at_slot(current_slot) current_epoch <= ws_state_epoch + ws_period