Merge pull request #1522 from ethereum/master

backport v093 to dev
2025-02-20 14:28:22 +00:00 · 2019-12-13 18:56:31 +01:00 · 2019-12-13 18:56:31 +01:00 · 88e954a9c7
commit 88e954a9c7
parent 4271d3b0a2 e7c5d64ce8
24 changed files with 1038 additions and 420 deletions
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@ -103,6 +103,15 @@ jobs:
          command: make citest
      - store_test_results:
          path: test_libs/pyspec/test-reports
+  table_of_contents:
+    docker:
+      - image: circleci/node:10.16.3
+    working_directory: ~/specs-repo
+    steps:
+      - checkout
+      - run:
+          name: Check table of contents
+          command: sudo npm install -g doctoc && make check_toc
  lint:
    docker:
      - image: circleci/python:3.6
@ -148,6 +157,7 @@ workflows:
      - test:
          requires:
            - install_pyspec_test
+      - table_of_contents
      - lint:
          requires:
            - test
--- a/18
+++ b/18
@ -17,18 +17,22 @@ GENERATOR_VENVS = $(patsubst $(GENERATOR_DIR)/%, $(GENERATOR_DIR)/%venv, $(GENER
 #$(info $$GENERATOR_TARGETS is [${GENERATOR_TARGETS}])

 PY_SPEC_PHASE_0_TARGETS = $(PY_SPEC_DIR)/eth2spec/phase0/spec.py
-PY_SPEC_PHASE_0_DEPS = $(SPEC_DIR)/core/0_*.md
+PY_SPEC_PHASE_0_DEPS = $(wildcard $(SPEC_DIR)/core/0_*.md)

 PY_SPEC_PHASE_1_TARGETS = $(PY_SPEC_DIR)/eth2spec/phase1/spec.py
-PY_SPEC_PHASE_1_DEPS = $(SPEC_DIR)/core/1_*.md
+PY_SPEC_PHASE_1_DEPS = $(wildcard $(SPEC_DIR)/core/1_*.md)
+
+PY_SPEC_ALL_DEPS = $(PY_SPEC_PHASE_0_DEPS) $(PY_SPEC_PHASE_1_DEPS)

 PY_SPEC_ALL_TARGETS = $(PY_SPEC_PHASE_0_TARGETS) $(PY_SPEC_PHASE_1_TARGETS)

+MARKDOWN_FILES = $(PY_SPEC_ALL_DEPS) $(wildcard $(SPEC_DIR)/*.md) $(wildcard $(SPEC_DIR)/light_client/*.md) $(wildcard $(SPEC_DIR)/networking/*.md) $(wildcard $(SPEC_DIR)/validator/*.md)
+
 COV_HTML_OUT=.htmlcov
 COV_INDEX_FILE=$(PY_SPEC_DIR)/$(COV_HTML_OUT)/index.html

 .PHONY: clean partial_clean all test citest lint generate_tests pyspec phase0 phase1 install_test open_cov \
-        install_deposit_contract_test test_deposit_contract compile_deposit_contract
+        install_deposit_contract_test test_deposit_contract compile_deposit_contract check_toc

 all: $(PY_SPEC_ALL_TARGETS)

@ -65,6 +69,14 @@ citest: $(PY_SPEC_ALL_TARGETS)
 open_cov:
 	((open "$(COV_INDEX_FILE)" || xdg-open "$(COV_INDEX_FILE)") &> /dev/null) &

+check_toc: $(MARKDOWN_FILES:=.toc)
+
+%.toc:
+	cp $* $*.tmp && \
+	doctoc $* && \
+	diff -q $* $*.tmp && \
+	rm $*.tmp
+
 lint: $(PY_SPEC_ALL_TARGETS)
 	cd $(PY_SPEC_DIR); . venv/bin/activate; \
 	flake8  --ignore=E252,W504,W503 --max-line-length=120 ./eth2spec \
--- a/scripts/build_spec.py
+++ b/scripts/build_spec.py
@ -82,7 +82,7 @@ def get_eth1_data(distance: uint64) -> Bytes32:
    return hash(distance)


-def hash(x: bytes) -> Bytes32:
+def hash(x: bytes) -> Bytes32:  # type: ignore
    if x not in hash_cache:
        hash_cache[x] = Bytes32(_hash(x))
    return hash_cache[x]
--- a/specs/bls_signature.md
+++ b/specs/bls_signature.md
@ -6,23 +6,25 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [BLS signature verification](#bls-signature-verification)
-    - [Table of contents](#table-of-contents)
-    - [Curve parameters](#curve-parameters)
-    - [Point representations](#point-representations)
-        - [G1 points](#g1-points)
-        - [G2 points](#g2-points)
-    - [Helpers](#helpers)
-        - [`hash_to_G2`](#hash_to_g2)
-        - [`modular_squareroot`](#modular_squareroot)
-    - [Aggregation operations](#aggregation-operations)
-        - [`bls_aggregate_pubkeys`](#bls_aggregate_pubkeys)
-        - [`bls_aggregate_signatures`](#bls_aggregate_signatures)
-    - [Signature verification](#signature-verification)
-        - [`bls_verify`](#bls_verify)
-        - [`bls_verify_multiple`](#bls_verify_multiple)

+- [Curve parameters](#curve-parameters)
+- [Point representations](#point-representations)
+  - [G1 points](#g1-points)
+  - [G2 points](#g2-points)
+- [Helpers](#helpers)
+  - [`hash_to_G2`](#hash_to_g2)
+  - [`modular_squareroot`](#modular_squareroot)
+- [Aggregation operations](#aggregation-operations)
+  - [`bls_aggregate_pubkeys`](#bls_aggregate_pubkeys)
+  - [`bls_aggregate_signatures`](#bls_aggregate_signatures)
+- [Signature verification](#signature-verification)
+  - [`bls_verify`](#bls_verify)
+  - [`bls_verify_multiple`](#bls_verify_multiple)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Curve parameters
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@ -4,119 +4,123 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 0 -- The Beacon Chain](#ethereum-20-phase-0----the-beacon-chain)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Notation](#notation)
-    - [Custom types](#custom-types)
-    - [Constants](#constants)
-    - [Configuration](#configuration)
-        - [Misc](#misc)
-        - [Gwei values](#gwei-values)
-        - [Initial values](#initial-values)
-        - [Time parameters](#time-parameters)
-        - [State list lengths](#state-list-lengths)
-        - [Rewards and penalties](#rewards-and-penalties)
-        - [Max operations per block](#max-operations-per-block)
-        - [Domain types](#domain-types)
-    - [Containers](#containers)
-        - [Misc dependencies](#misc-dependencies)
-            - [`Fork`](#fork)
-            - [`Checkpoint`](#checkpoint)
-            - [`Validator`](#validator)
-            - [`AttestationData`](#attestationdata)
-            - [`IndexedAttestation`](#indexedattestation)
-            - [`PendingAttestation`](#pendingattestation)
-            - [`Eth1Data`](#eth1data)
-            - [`HistoricalBatch`](#historicalbatch)
-            - [`DepositMessage`](#depositmessage)
-            - [`DepositData`](#depositdata)
-            - [`BeaconBlockHeader`](#beaconblockheader)
-        - [Beacon operations](#beacon-operations)
-            - [`ProposerSlashing`](#proposerslashing)
-            - [`AttesterSlashing`](#attesterslashing)
-            - [`Attestation`](#attestation)
-            - [`Deposit`](#deposit)
-            - [`VoluntaryExit`](#voluntaryexit)
-        - [Beacon blocks](#beacon-blocks)
-            - [`BeaconBlockBody`](#beaconblockbody)
-            - [`BeaconBlock`](#beaconblock)
-        - [Beacon state](#beacon-state)
-            - [`BeaconState`](#beaconstate)
-        - [Signed envelopes](#signed-envelopes)
-            - [`SignedVoluntaryExit`](#signedvoluntaryexit)
-            - [`SignedBeaconBlock`](#signedbeaconblock)
-            - [`SignedBeaconBlockHeader`](#signedbeaconblockheader)
-    - [Helper functions](#helper-functions)
-        - [Math](#math)
-            - [`integer_squareroot`](#integer_squareroot)
-            - [`xor`](#xor)
-            - [`int_to_bytes`](#int_to_bytes)
-            - [`bytes_to_int`](#bytes_to_int)
-        - [Crypto](#crypto)
-            - [`hash`](#hash)
-            - [`hash_tree_root`](#hash_tree_root)
-            - [`bls_verify`](#bls_verify)
-            - [`bls_aggregate_pubkeys`](#bls_aggregate_pubkeys)
-        - [Predicates](#predicates)
-            - [`is_active_validator`](#is_active_validator)
-            - [`is_slashable_validator`](#is_slashable_validator)
-            - [`is_slashable_attestation_data`](#is_slashable_attestation_data)
-            - [`is_valid_indexed_attestation`](#is_valid_indexed_attestation)
-            - [`is_valid_merkle_branch`](#is_valid_merkle_branch)
-        - [Misc](#misc-1)
-            - [`compute_shuffled_index`](#compute_shuffled_index)
-            - [`compute_proposer_index`](#compute_proposer_index)
-            - [`compute_committee`](#compute_committee)
-            - [`compute_epoch_at_slot`](#compute_epoch_at_slot)
-            - [`compute_start_slot_at_epoch`](#compute_start_slot_at_epoch)
-            - [`compute_activation_exit_epoch`](#compute_activation_exit_epoch)
-            - [`compute_domain`](#compute_domain)
-        - [Beacon state accessors](#beacon-state-accessors)
-            - [`get_current_epoch`](#get_current_epoch)
-            - [`get_previous_epoch`](#get_previous_epoch)
-            - [`get_block_root`](#get_block_root)
-            - [`get_block_root_at_slot`](#get_block_root_at_slot)
-            - [`get_randao_mix`](#get_randao_mix)
-            - [`get_active_validator_indices`](#get_active_validator_indices)
-            - [`get_validator_churn_limit`](#get_validator_churn_limit)
-            - [`get_seed`](#get_seed)
-            - [`get_committee_count_at_slot`](#get_committee_count_at_slot)
-            - [`get_beacon_committee`](#get_beacon_committee)
-            - [`get_beacon_proposer_index`](#get_beacon_proposer_index)
-            - [`get_total_balance`](#get_total_balance)
-            - [`get_total_active_balance`](#get_total_active_balance)
-            - [`get_domain`](#get_domain)
-            - [`get_indexed_attestation`](#get_indexed_attestation)
-            - [`get_attesting_indices`](#get_attesting_indices)
-        - [Beacon state mutators](#beacon-state-mutators)
-            - [`increase_balance`](#increase_balance)
-            - [`decrease_balance`](#decrease_balance)
-            - [`initiate_validator_exit`](#initiate_validator_exit)
-            - [`slash_validator`](#slash_validator)
-    - [Genesis](#genesis)
-        - [Genesis state](#genesis-state)
-        - [Genesis block](#genesis-block)
-    - [Beacon chain state transition function](#beacon-chain-state-transition-function)
-        - [Epoch processing](#epoch-processing)
-            - [Helper functions](#helper-functions-1)
-            - [Justification and finalization](#justification-and-finalization)
-            - [Rewards and penalties](#rewards-and-penalties-1)
-            - [Registry updates](#registry-updates)
-            - [Slashings](#slashings)
-            - [Final updates](#final-updates)
-        - [Block processing](#block-processing)
-            - [Block header](#block-header)
-            - [RANDAO](#randao)
-            - [Eth1 data](#eth1-data)
-            - [Operations](#operations)
-                - [Proposer slashings](#proposer-slashings)
-                - [Attester slashings](#attester-slashings)
-                - [Attestations](#attestations)
-                - [Deposits](#deposits)
-                - [Voluntary exits](#voluntary-exits)

+- [Introduction](#introduction)
+- [Notation](#notation)
+- [Custom types](#custom-types)
+- [Constants](#constants)
+- [Configuration](#configuration)
+  - [Misc](#misc)
+  - [Gwei values](#gwei-values)
+  - [Initial values](#initial-values)
+  - [Time parameters](#time-parameters)
+  - [State list lengths](#state-list-lengths)
+  - [Rewards and penalties](#rewards-and-penalties)
+  - [Max operations per block](#max-operations-per-block)
+  - [Domain types](#domain-types)
+- [Containers](#containers)
+  - [Misc dependencies](#misc-dependencies)
+    - [`Fork`](#fork)
+    - [`Checkpoint`](#checkpoint)
+    - [`Validator`](#validator)
+    - [`AttestationData`](#attestationdata)
+    - [`IndexedAttestation`](#indexedattestation)
+    - [`PendingAttestation`](#pendingattestation)
+    - [`Eth1Data`](#eth1data)
+    - [`HistoricalBatch`](#historicalbatch)
+    - [`DepositMessage`](#depositmessage)
+    - [`DepositData`](#depositdata)
+    - [`BeaconBlockHeader`](#beaconblockheader)
+  - [Beacon operations](#beacon-operations)
+    - [`ProposerSlashing`](#proposerslashing)
+    - [`AttesterSlashing`](#attesterslashing)
+    - [`Attestation`](#attestation)
+    - [`Deposit`](#deposit)
+    - [`VoluntaryExit`](#voluntaryexit)
+  - [Beacon blocks](#beacon-blocks)
+    - [`BeaconBlockBody`](#beaconblockbody)
+    - [`BeaconBlock`](#beaconblock)
+  - [Beacon state](#beacon-state)
+    - [`BeaconState`](#beaconstate)
+  - [Signed envelopes](#signed-envelopes)
+    - [`SignedVoluntaryExit`](#signedvoluntaryexit)
+    - [`SignedBeaconBlock`](#signedbeaconblock)
+    - [`SignedBeaconBlockHeader`](#signedbeaconblockheader)
+- [Helper functions](#helper-functions)
+  - [Math](#math)
+    - [`integer_squareroot`](#integer_squareroot)
+    - [`xor`](#xor)
+    - [`int_to_bytes`](#int_to_bytes)
+    - [`bytes_to_int`](#bytes_to_int)
+  - [Crypto](#crypto)
+    - [`hash`](#hash)
+    - [`hash_tree_root`](#hash_tree_root)
+    - [`bls_verify`](#bls_verify)
+    - [`bls_aggregate_pubkeys`](#bls_aggregate_pubkeys)
+  - [Predicates](#predicates)
+    - [`is_active_validator`](#is_active_validator)
+    - [`is_eligible_for_activation_queue`](#is_eligible_for_activation_queue)
+    - [`is_eligible_for_activation`](#is_eligible_for_activation)
+    - [`is_slashable_validator`](#is_slashable_validator)
+    - [`is_slashable_attestation_data`](#is_slashable_attestation_data)
+    - [`is_valid_indexed_attestation`](#is_valid_indexed_attestation)
+    - [`is_valid_merkle_branch`](#is_valid_merkle_branch)
+  - [Misc](#misc-1)
+    - [`compute_shuffled_index`](#compute_shuffled_index)
+    - [`compute_proposer_index`](#compute_proposer_index)
+    - [`compute_committee`](#compute_committee)
+    - [`compute_epoch_at_slot`](#compute_epoch_at_slot)
+    - [`compute_start_slot_at_epoch`](#compute_start_slot_at_epoch)
+    - [`compute_activation_exit_epoch`](#compute_activation_exit_epoch)
+    - [`compute_domain`](#compute_domain)
+  - [Beacon state accessors](#beacon-state-accessors)
+    - [`get_current_epoch`](#get_current_epoch)
+    - [`get_previous_epoch`](#get_previous_epoch)
+    - [`get_block_root`](#get_block_root)
+    - [`get_block_root_at_slot`](#get_block_root_at_slot)
+    - [`get_randao_mix`](#get_randao_mix)
+    - [`get_active_validator_indices`](#get_active_validator_indices)
+    - [`get_validator_churn_limit`](#get_validator_churn_limit)
+    - [`get_seed`](#get_seed)
+    - [`get_committee_count_at_slot`](#get_committee_count_at_slot)
+    - [`get_beacon_committee`](#get_beacon_committee)
+    - [`get_beacon_proposer_index`](#get_beacon_proposer_index)
+    - [`get_total_balance`](#get_total_balance)
+    - [`get_total_active_balance`](#get_total_active_balance)
+    - [`get_domain`](#get_domain)
+    - [`get_indexed_attestation`](#get_indexed_attestation)
+    - [`get_attesting_indices`](#get_attesting_indices)
+  - [Beacon state mutators](#beacon-state-mutators)
+    - [`increase_balance`](#increase_balance)
+    - [`decrease_balance`](#decrease_balance)
+    - [`initiate_validator_exit`](#initiate_validator_exit)
+    - [`slash_validator`](#slash_validator)
+- [Genesis](#genesis)
+  - [Genesis state](#genesis-state)
+  - [Genesis block](#genesis-block)
+- [Beacon chain state transition function](#beacon-chain-state-transition-function)
+  - [Epoch processing](#epoch-processing)
+    - [Helper functions](#helper-functions-1)
+    - [Justification and finalization](#justification-and-finalization)
+    - [Rewards and penalties](#rewards-and-penalties-1)
+    - [Registry updates](#registry-updates)
+    - [Slashings](#slashings)
+    - [Final updates](#final-updates)
+  - [Block processing](#block-processing)
+    - [Block header](#block-header)
+    - [RANDAO](#randao)
+    - [Eth1 data](#eth1-data)
+    - [Operations](#operations)
+      - [Proposer slashings](#proposer-slashings)
+      - [Attester slashings](#attester-slashings)
+      - [Attestations](#attestations)
+      - [Deposits](#deposits)
+      - [Voluntary exits](#voluntary-exits)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
@ -484,7 +488,7 @@ class BeaconState(Container):

 ### Signed envelopes

-Some messages in the protocol are wrapped in an envelop to better facilitate adding/pruning the signature and to `hash_tree_root` the `message` separate from the signature.  
+Some messages in the protocol are wrapped in an envelope to better facilitate adding/pruning the signature and to `hash_tree_root` the `message` separate from the signature.  

 #### `SignedVoluntaryExit`

@ -591,6 +595,34 @@ def is_active_validator(validator: Validator, epoch: Epoch) -> bool:
    return validator.activation_epoch <= epoch < validator.exit_epoch
 ```

+#### `is_eligible_for_activation_queue`
+
+```python
+def is_eligible_for_activation_queue(validator: Validator) -> bool:
+    """
+    Check if ``validator`` is eligible to be placed into the activation queue.
+    """
+    return (
+        validator.activation_eligibility_epoch == FAR_FUTURE_EPOCH
+        and validator.effective_balance == MAX_EFFECTIVE_BALANCE
+    )
+```
+
+#### `is_eligible_for_activation`
+
+```python
+def is_eligible_for_activation(state: BeaconState, validator: Validator) -> bool:
+    """
+    Check if ``validator`` is eligible for activation.
+    """
+    return (
+        # Placement in queue is finalized
+        validator.activation_eligibility_epoch <= state.finalized_checkpoint.epoch
+        # Has not yet been activated
+        and validator.activation_epoch == FAR_FUTURE_EPOCH
+    )
+```
+
 #### `is_slashable_validator`

 ```python
@ -628,8 +660,8 @@ def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
    # Verify max number of indices
    if not len(indices) <= MAX_VALIDATORS_PER_COMMITTEE:
        return False
-    # Verify indices are sorted
-    if not indices == sorted(indices):
+    # Verify indices are sorted and unique
+    if not indices == sorted(set(indices)):
        return False
    # Verify aggregate signature
    if not bls_verify(
@ -1302,26 +1334,22 @@ def process_rewards_and_penalties(state: BeaconState) -> None:
 def process_registry_updates(state: BeaconState) -> None:
    # Process activation eligibility and ejections
    for index, validator in enumerate(state.validators):
-        if (
-            validator.activation_eligibility_epoch == FAR_FUTURE_EPOCH
-            and validator.effective_balance == MAX_EFFECTIVE_BALANCE
-        ):
-            validator.activation_eligibility_epoch = get_current_epoch(state)
+        if is_eligible_for_activation_queue(validator):
+            validator.activation_eligibility_epoch = get_current_epoch(state) + 1

        if is_active_validator(validator, get_current_epoch(state)) and validator.effective_balance <= EJECTION_BALANCE:
            initiate_validator_exit(state, ValidatorIndex(index))

-    # Queue validators eligible for activation and not dequeued for activation prior to finalized epoch
+    # Queue validators eligible for activation and not yet dequeued for activation
    activation_queue = sorted([
        index for index, validator in enumerate(state.validators)
-        if validator.activation_eligibility_epoch != FAR_FUTURE_EPOCH
-        and validator.activation_epoch >= compute_activation_exit_epoch(state.finalized_checkpoint.epoch)
-    ], key=lambda index: state.validators[index].activation_eligibility_epoch)
-    # Dequeued validators for activation up to churn limit (without resetting activation epoch)
+        if is_eligible_for_activation(state, validator)
+        # Order by the sequence of activation_eligibility_epoch setting and then index
+    ], key=lambda index: (state.validators[index].activation_eligibility_epoch, index))
+    # Dequeued validators for activation up to churn limit
    for index in activation_queue[:get_validator_churn_limit(state)]:
        validator = state.validators[index]
-        if validator.activation_epoch == FAR_FUTURE_EPOCH:
-            validator.activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
+        validator.activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
 ```

 #### Slashings
@ -1482,6 +1510,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
    data = attestation.data
    assert data.index < get_committee_count_at_slot(state, data.slot)
    assert data.target.epoch in (get_previous_epoch(state), get_current_epoch(state))
+    assert data.target.epoch == compute_epoch_at_slot(data.slot)
    assert data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot <= data.slot + SLOTS_PER_EPOCH

    committee = get_beacon_committee(state, data.slot, data.index)
--- a/specs/core/0_deposit-contract.md
+++ b/specs/core/0_deposit-contract.md
@ -4,19 +4,21 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 0 -- Deposit Contract](#ethereum-20-phase-0----deposit-contract)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Constants](#constants)
-        - [Contract](#contract)
-    - [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract)
-        - [`deposit` function](#deposit-function)
-            - [Deposit amount](#deposit-amount)
-            - [Withdrawal credentials](#withdrawal-credentials)
-            - [`DepositEvent` log](#depositevent-log)
-    - [Vyper code](#vyper-code)

+- [Introduction](#introduction)
+- [Constants](#constants)
+  - [Contract](#contract)
+- [Ethereum 1.0 deposit contract](#ethereum-10-deposit-contract)
+  - [`deposit` function](#deposit-function)
+    - [Deposit amount](#deposit-amount)
+    - [Withdrawal credentials](#withdrawal-credentials)
+    - [`DepositEvent` log](#depositevent-log)
+- [Vyper code](#vyper-code)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
--- a/specs/core/0_fork-choice.md
+++ b/specs/core/0_fork-choice.md
@ -4,23 +4,32 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 0 -- Beacon Chain Fork Choice](#ethereum-20-phase-0----beacon-chain-fork-choice)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Fork choice](#fork-choice)
-        - [Helpers](#helpers)
-            - [`LatestMessage`](#latestmessage)
-            - [`Store`](#store)
-            - [`get_genesis_store`](#get_genesis_store)
-            - [`get_ancestor`](#get_ancestor)
-            - [`get_latest_attesting_balance`](#get_latest_attesting_balance)
-            - [`get_head`](#get_head)
-        - [Handlers](#handlers)
-            - [`on_tick`](#on_tick)
-            - [`on_block`](#on_block)
-            - [`on_attestation`](#on_attestation)

+- [Introduction](#introduction)
+- [Fork choice](#fork-choice)
+  - [Configuration](#configuration)
+  - [Helpers](#helpers)
+    - [`LatestMessage`](#latestmessage)
+    - [`Store`](#store)
+    - [`get_genesis_store`](#get_genesis_store)
+    - [`get_slots_since_genesis`](#get_slots_since_genesis)
+    - [`get_current_slot`](#get_current_slot)
+    - [`compute_slots_since_epoch_start`](#compute_slots_since_epoch_start)
+    - [`get_ancestor`](#get_ancestor)
+    - [`get_latest_attesting_balance`](#get_latest_attesting_balance)
+    - [`filter_block_tree`](#filter_block_tree)
+    - [`get_filtered_block_tree`](#get_filtered_block_tree)
+    - [`get_head`](#get_head)
+    - [`should_update_justified_checkpoint`](#should_update_justified_checkpoint)
+  - [Handlers](#handlers)
+    - [`on_tick`](#on_tick)
+    - [`on_block`](#on_block)
+    - [`on_attestation`](#on_attestation)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
@ -96,11 +105,18 @@ def get_genesis_store(genesis_state: BeaconState) -> Store:
    )
 ```

+#### `get_slots_since_genesis`
+
+```python
+def get_slots_since_genesis(store: Store) -> int:
+    return (store.time - store.genesis_time) // SECONDS_PER_SLOT
+```
+
 #### `get_current_slot`

 ```python
 def get_current_slot(store: Store) -> Slot:
-    return Slot((store.time - store.genesis_time) // SECONDS_PER_SLOT)
+    return Slot(GENESIS_SLOT + get_slots_since_genesis(store))
 ```

 #### `compute_slots_since_epoch_start`
@ -136,17 +152,72 @@ def get_latest_attesting_balance(store: Store, root: Root) -> Gwei:
    ))
 ```

+#### `filter_block_tree`
+
+```python
+def filter_block_tree(store: Store, block_root: Root, blocks: Dict[Root, BeaconBlock]) -> bool:
+    block = store.blocks[block_root]
+    children = [
+        root for root in store.blocks.keys()
+        if store.blocks[root].parent_root == block_root
+    ]
+
+    # If any children branches contain expected finalized/justified checkpoints,
+    # add to filtered block-tree and signal viability to parent.
+    if any(children):
+        filter_block_tree_result = [filter_block_tree(store, child, blocks) for child in children]
+        if any(filter_block_tree_result):
+            blocks[block_root] = block
+            return True
+        return False
+
+    # If leaf block, check finalized/justified checkpoints as matching latest.
+    head_state = store.block_states[block_root]
+
+    correct_justified = (
+        store.justified_checkpoint.epoch == GENESIS_EPOCH
+        or head_state.current_justified_checkpoint == store.justified_checkpoint
+    )
+    correct_finalized = (
+        store.finalized_checkpoint.epoch == GENESIS_EPOCH
+        or head_state.finalized_checkpoint == store.finalized_checkpoint
+    )
+    # If expected finalized/justified, add to viable block-tree and signal viability to parent.
+    if correct_justified and correct_finalized:
+        blocks[block_root] = block
+        return True
+
+    # Otherwise, branch not viable
+    return False
+```
+
+#### `get_filtered_block_tree`
+
+```python
+def get_filtered_block_tree(store: Store) -> Dict[Root, BeaconBlock]:
+    """
+    Retrieve a filtered block true from ``store``, only returning branches
+    whose leaf state's justified/finalized info agrees with that in ``store``.
+    """
+    base = store.justified_checkpoint.root
+    blocks: Dict[Root, BeaconBlock] = {}
+    filter_block_tree(store, base, blocks)
+    return blocks
+```
+
 #### `get_head`

 ```python
 def get_head(store: Store) -> Root:
+    # Get filtered block tree that only includes viable branches
+    blocks = get_filtered_block_tree(store)
    # Execute the LMD-GHOST fork choice
    head = store.justified_checkpoint.root
    justified_slot = compute_start_slot_at_epoch(store.justified_checkpoint.epoch)
    while True:
        children = [
-            root for root in store.blocks.keys()
-            if store.blocks[root].parent_root == head and store.blocks[root].slot > justified_slot
+            root for root in blocks.keys()
+            if blocks[root].parent_root == head and blocks[root].slot > justified_slot
        ]
        if len(children) == 0:
            return head
@ -172,8 +243,8 @@ def should_update_justified_checkpoint(store: Store, new_justified_checkpoint: C
    if new_justified_block.slot <= compute_start_slot_at_epoch(store.justified_checkpoint.epoch):
        return False
    if not (
-        get_ancestor(store, new_justified_checkpoint.root, store.blocks[store.justified_checkpoint.root].slot) ==
-        store.justified_checkpoint.root
+        get_ancestor(store, new_justified_checkpoint.root, store.blocks[store.justified_checkpoint.root].slot)
+        == store.justified_checkpoint.root
    ):
        return False

@ -209,7 +280,7 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:
    assert block.parent_root in store.block_states
    pre_state = store.block_states[block.parent_root].copy()
    # Blocks cannot be in the future. If they are, their consideration must be delayed until the are in the past.
-    assert store.time >= pre_state.genesis_time + block.slot * SECONDS_PER_SLOT
+    assert get_current_slot(store) >= block.slot
    # Add new block to the store
    store.blocks[hash_tree_root(block)] = block
    # Check block is a descendant of the finalized block
@ -226,7 +297,8 @@ def on_block(store: Store, signed_block: SignedBeaconBlock) -> None:

    # Update justified checkpoint
    if state.current_justified_checkpoint.epoch > store.justified_checkpoint.epoch:
-        store.best_justified_checkpoint = state.current_justified_checkpoint
+        if state.current_justified_checkpoint.epoch > store.best_justified_checkpoint.epoch:
+            store.best_justified_checkpoint = state.current_justified_checkpoint
        if should_update_justified_checkpoint(store, state.current_justified_checkpoint):
            store.justified_checkpoint = state.current_justified_checkpoint

@ -252,12 +324,13 @@ def on_attestation(store: Store, attestation: Attestation) -> None:
    # Use GENESIS_EPOCH for previous when genesis to avoid underflow
    previous_epoch = current_epoch - 1 if current_epoch > GENESIS_EPOCH else GENESIS_EPOCH
    assert target.epoch in [current_epoch, previous_epoch]
+    assert target.epoch == compute_epoch_at_slot(attestation.data.slot)

    # Attestations target be for a known block. If target block is unknown, delay consideration until the block is found
    assert target.root in store.blocks
    # Attestations cannot be from future epochs. If they are, delay consideration until the epoch arrives
    base_state = store.block_states[target.root].copy()
-    assert store.time >= base_state.genesis_time + compute_start_slot_at_epoch(target.epoch) * SECONDS_PER_SLOT
+    assert get_current_slot(store) >= compute_start_slot_at_epoch(target.epoch)

    # Attestations must be for a known block. If block is unknown, delay consideration until the block is found
    assert attestation.data.beacon_block_root in store.blocks
@ -272,7 +345,7 @@ def on_attestation(store: Store, attestation: Attestation) -> None:

    # Attestations can only affect the fork choice of subsequent slots.
    # Delay consideration in the fork choice until their slot is in the past.
-    assert store.time >= (attestation.data.slot + 1) * SECONDS_PER_SLOT
+    assert get_current_slot(store) >= attestation.data.slot + 1

    # Get state at the `target` to validate attestation and calculate the committees
    indexed_attestation = get_indexed_attestation(target_state, attestation)
--- a/specs/core/1_beacon-chain-misc.md
+++ b/specs/core/1_beacon-chain-misc.md
@ -3,29 +3,31 @@
 ## Table of contents

 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Phase 1 miscellaneous beacon chain changes](#phase-1-miscellaneous-beacon-chain-changes)
-    - [Table of contents](#table-of-contents)
-    - [Configuration](#configuration)
-    - [Containers](#containers)
-        - [`CompactCommittee`](#compactcommittee)
-        - [`ShardReceiptDelta`](#shardreceiptdelta)
-        - [`ShardReceiptProof`](#shardreceiptproof)
-    - [Helper functions](#helper-functions)
-        - [`pack_compact_validator`](#pack_compact_validator)
-        - [`unpack_compact_validator`](#unpack_compact_validator)
-        - [`committee_to_compact_committee`](#committee_to_compact_committee)
-        - [`verify_merkle_proof`](#verify_merkle_proof)
-        - [`compute_historical_state_generalized_index`](#compute_historical_state_generalized_index)
-        - [`get_generalized_index_of_crosslink_header`](#get_generalized_index_of_crosslink_header)
-        - [`process_shard_receipt_proof`](#process_shard_receipt_proof)
-    - [Changes](#changes)
-        - [Phase 0 container updates](#phase-0-container-updates)
-            - [`BeaconState`](#beaconstate)
-            - [`BeaconBlockBody`](#beaconblockbody)
-        - [Persistent committees](#persistent-committees)
-        - [Shard receipt processing](#shard-receipt-processing)

+- [Configuration](#configuration)
+- [Containers](#containers)
+    - [`CompactCommittee`](#compactcommittee)
+    - [`ShardReceiptDelta`](#shardreceiptdelta)
+    - [`ShardReceiptProof`](#shardreceiptproof)
+- [Helper functions](#helper-functions)
+    - [`pack_compact_validator`](#pack_compact_validator)
+    - [`unpack_compact_validator`](#unpack_compact_validator)
+    - [`committee_to_compact_committee`](#committee_to_compact_committee)
+    - [`verify_merkle_proof`](#verify_merkle_proof)
+    - [`compute_historical_state_generalized_index`](#compute_historical_state_generalized_index)
+    - [`get_generalized_index_of_crosslink_header`](#get_generalized_index_of_crosslink_header)
+    - [`process_shard_receipt_proof`](#process_shard_receipt_proof)
+- [Changes](#changes)
+  - [Phase 0 container updates](#phase-0-container-updates)
+    - [`BeaconState`](#beaconstate)
+    - [`BeaconBlockBody`](#beaconblockbody)
+  - [Persistent committees](#persistent-committees)
+  - [Shard receipt processing](#shard-receipt-processing)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Configuration
--- a/specs/core/1_custody-game.md
+++ b/specs/core/1_custody-game.md
@ -5,54 +5,56 @@
 ## Table of contents

 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 1 -- Custody Game](#ethereum-20-phase-1----custody-game)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Terminology](#terminology)
-    - [Constants](#constants)
-        - [Misc](#misc)
-        - [Custody game parameters](#custody-game-parameters)
-        - [Time parameters](#time-parameters)
-        - [Max operations per block](#max-operations-per-block)
-        - [Reward and penalty quotients](#reward-and-penalty-quotients)
-        - [Signature domain types](#signature-domain-types)
-        - [TODO PLACEHOLDER](#todo-placeholder)
-    - [Data structures](#data-structures)
-        - [Custody objects](#custody-objects)
-            - [`CustodyChunkChallenge`](#custodychunkchallenge)
-            - [`CustodyBitChallenge`](#custodybitchallenge)
-            - [`CustodyChunkChallengeRecord`](#custodychunkchallengerecord)
-            - [`CustodyBitChallengeRecord`](#custodybitchallengerecord)
-            - [`CustodyResponse`](#custodyresponse)
-        - [New beacon operations](#new-beacon-operations)
-            - [`CustodyKeyReveal`](#custodykeyreveal)
-            - [`EarlyDerivedSecretReveal`](#earlyderivedsecretreveal)
-        - [Phase 0 container updates](#phase-0-container-updates)
-            - [`Validator`](#validator)
-            - [`BeaconState`](#beaconstate)
-            - [`BeaconBlockBody`](#beaconblockbody)
-    - [Helpers](#helpers)
-        - [`ceillog2`](#ceillog2)
-        - [`is_valid_merkle_branch_with_mixin`](#is_valid_merkle_branch_with_mixin)
-        - [`get_crosslink_chunk_count`](#get_crosslink_chunk_count)
-        - [`legendre_bit`](#legendre_bit)
-        - [`custody_subchunkify`](#custody_subchunkify)
-        - [`get_custody_chunk_bit`](#get_custody_chunk_bit)
-        - [`get_chunk_bits_root`](#get_chunk_bits_root)
-        - [`get_randao_epoch_for_custody_period`](#get_randao_epoch_for_custody_period)
-        - [`get_custody_period_for_validator`](#get_custody_period_for_validator)
-        - [`replace_empty_or_append`](#replace_empty_or_append)
-    - [Per-block processing](#per-block-processing)
-        - [Operations](#operations)
-            - [Custody key reveals](#custody-key-reveals)
-            - [Early derived secret reveals](#early-derived-secret-reveals)
-            - [Chunk challenges](#chunk-challenges)
-            - [Bit challenges](#bit-challenges)
-            - [Custody responses](#custody-responses)
-    - [Per-epoch processing](#per-epoch-processing)
-        - [Handling of custody-related deadlines](#handling-of-custody-related-deadlines)

+- [Introduction](#introduction)
+- [Terminology](#terminology)
+- [Constants](#constants)
+  - [Misc](#misc)
+  - [Custody game parameters](#custody-game-parameters)
+  - [Time parameters](#time-parameters)
+  - [Max operations per block](#max-operations-per-block)
+  - [Reward and penalty quotients](#reward-and-penalty-quotients)
+  - [Signature domain types](#signature-domain-types)
+  - [TODO PLACEHOLDER](#todo-placeholder)
+- [Data structures](#data-structures)
+  - [Custody objects](#custody-objects)
+    - [`CustodyChunkChallenge`](#custodychunkchallenge)
+    - [`CustodyBitChallenge`](#custodybitchallenge)
+    - [`CustodyChunkChallengeRecord`](#custodychunkchallengerecord)
+    - [`CustodyBitChallengeRecord`](#custodybitchallengerecord)
+    - [`CustodyResponse`](#custodyresponse)
+  - [New beacon operations](#new-beacon-operations)
+    - [`CustodyKeyReveal`](#custodykeyreveal)
+    - [`EarlyDerivedSecretReveal`](#earlyderivedsecretreveal)
+  - [Phase 0 container updates](#phase-0-container-updates)
+    - [`Validator`](#validator)
+    - [`BeaconState`](#beaconstate)
+    - [`BeaconBlockBody`](#beaconblockbody)
+- [Helpers](#helpers)
+  - [`ceillog2`](#ceillog2)
+  - [`is_valid_merkle_branch_with_mixin`](#is_valid_merkle_branch_with_mixin)
+  - [`get_crosslink_chunk_count`](#get_crosslink_chunk_count)
+  - [`legendre_bit`](#legendre_bit)
+  - [`custody_subchunkify`](#custody_subchunkify)
+  - [`get_custody_chunk_bit`](#get_custody_chunk_bit)
+  - [`get_chunk_bits_root`](#get_chunk_bits_root)
+  - [`get_randao_epoch_for_custody_period`](#get_randao_epoch_for_custody_period)
+  - [`get_custody_period_for_validator`](#get_custody_period_for_validator)
+  - [`replace_empty_or_append`](#replace_empty_or_append)
+- [Per-block processing](#per-block-processing)
+  - [Operations](#operations)
+    - [Custody key reveals](#custody-key-reveals)
+    - [Early derived secret reveals](#early-derived-secret-reveals)
+    - [Chunk challenges](#chunk-challenges)
+    - [Bit challenges](#bit-challenges)
+    - [Custody responses](#custody-responses)
+- [Per-epoch processing](#per-epoch-processing)
+  - [Handling of custody-related deadlines](#handling-of-custody-related-deadlines)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
--- a/specs/core/1_shard-data-chains.md
+++ b/specs/core/1_shard-data-chains.md
@ -5,45 +5,47 @@
 ## Table of contents

 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 1 -- Shard Data Chains](#ethereum-20-phase-1----shard-data-chains)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Custom types](#custom-types)
-    - [Configuration](#configuration)
-        - [Misc](#misc)
-        - [Initial values](#initial-values)
-        - [Time parameters](#time-parameters)
-        - [State list lengths](#state-list-lengths)
-        - [Rewards and penalties](#rewards-and-penalties)
-        - [Signature domain types](#signature-domain-types)
-    - [Containers](#containers)
-        - [`Crosslink`](#crosslink)
-        - [`ShardBlock`](#shardblock)
-        - [`ShardBlockHeader`](#shardblockheader)
-        - [`ShardState`](#shardstate)
-        - [`ShardAttestationData`](#shardattestationdata)
-    - [Helper functions](#helper-functions)
-        - [Misc](#misc-1)
-            - [`compute_epoch_of_shard_slot`](#compute_epoch_of_shard_slot)
-            - [`compute_shard_period_start_epoch`](#compute_shard_period_start_epoch)
-        - [Beacon state accessors](#beacon-state-accessors)
-            - [`get_period_committee`](#get_period_committee)
-            - [`get_shard_committee`](#get_shard_committee)
-            - [`get_shard_proposer_index`](#get_shard_proposer_index)
-        - [Shard state mutators](#shard-state-mutators)
-            - [`process_delta`](#process_delta)
-    - [Genesis](#genesis)
-        - [`get_genesis_shard_state`](#get_genesis_shard_state)
-        - [`get_genesis_shard_block`](#get_genesis_shard_block)
-    - [Shard state transition function](#shard-state-transition-function)
-        - [Period processing](#period-processing)
-        - [Block processing](#block-processing)
-            - [Block header](#block-header)
-            - [Attestations](#attestations)
-            - [Block body](#block-body)
-    - [Shard fork choice rule](#shard-fork-choice-rule)

+- [Introduction](#introduction)
+- [Custom types](#custom-types)
+- [Configuration](#configuration)
+  - [Misc](#misc)
+  - [Initial values](#initial-values)
+  - [Time parameters](#time-parameters)
+  - [State list lengths](#state-list-lengths)
+  - [Rewards and penalties](#rewards-and-penalties)
+  - [Signature domain types](#signature-domain-types)
+- [Containers](#containers)
+  - [`Crosslink`](#crosslink)
+  - [`ShardBlock`](#shardblock)
+  - [`ShardBlockHeader`](#shardblockheader)
+  - [`ShardState`](#shardstate)
+  - [`ShardAttestationData`](#shardattestationdata)
+- [Helper functions](#helper-functions)
+  - [Misc](#misc-1)
+    - [`compute_epoch_of_shard_slot`](#compute_epoch_of_shard_slot)
+    - [`compute_shard_period_start_epoch`](#compute_shard_period_start_epoch)
+  - [Beacon state accessors](#beacon-state-accessors)
+    - [`get_period_committee`](#get_period_committee)
+    - [`get_shard_committee`](#get_shard_committee)
+    - [`get_shard_proposer_index`](#get_shard_proposer_index)
+  - [Shard state mutators](#shard-state-mutators)
+    - [`process_delta`](#process_delta)
+- [Genesis](#genesis)
+  - [`get_genesis_shard_state`](#get_genesis_shard_state)
+  - [`get_genesis_shard_block`](#get_genesis_shard_block)
+- [Shard state transition function](#shard-state-transition-function)
+  - [Period processing](#period-processing)
+  - [Block processing](#block-processing)
+    - [Block header](#block-header)
+    - [Attestations](#attestations)
+    - [Block body](#block-body)
+- [Shard fork choice rule](#shard-fork-choice-rule)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
--- a/specs/light_client/merkle_proofs.md
+++ b/specs/light_client/merkle_proofs.md
@ -4,21 +4,23 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Merkle proof formats](#merkle-proof-formats)
-    - [Table of contents](#table-of-contents)
-    - [Helper functions](#helper-functions)
-    - [Generalized Merkle tree index](#generalized-merkle-tree-index)
-    - [SSZ object to index](#ssz-object-to-index)
-        - [Helpers for generalized indices](#helpers-for-generalized-indices)
-            - [`concat_generalized_indices`](#concat_generalized_indices)
-            - [`get_generalized_index_length`](#get_generalized_index_length)
-            - [`get_generalized_index_bit`](#get_generalized_index_bit)
-            - [`generalized_index_sibling`](#generalized_index_sibling)
-            - [`generalized_index_child`](#generalized_index_child)
-            - [`generalized_index_parent`](#generalized_index_parent)
-    - [Merkle multiproofs](#merkle-multiproofs)

+- [Helper functions](#helper-functions)
+- [Generalized Merkle tree index](#generalized-merkle-tree-index)
+- [SSZ object to index](#ssz-object-to-index)
+  - [Helpers for generalized indices](#helpers-for-generalized-indices)
+    - [`concat_generalized_indices`](#concat_generalized_indices)
+    - [`get_generalized_index_length`](#get_generalized_index_length)
+    - [`get_generalized_index_bit`](#get_generalized_index_bit)
+    - [`generalized_index_sibling`](#generalized_index_sibling)
+    - [`generalized_index_child`](#generalized_index_child)
+    - [`generalized_index_parent`](#generalized_index_parent)
+- [Merkle multiproofs](#merkle-multiproofs)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Helper functions
--- a/specs/light_client/sync_protocol.md
+++ b/specs/light_client/sync_protocol.md
@ -5,20 +5,22 @@
 ## Table of contents

 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Minimal Light Client Design](#minimal-light-client-design)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Custom types](#custom-types)
-    - [Constants](#constants)
-    - [Containers](#containers)
-        - [`LightClientUpdate`](#lightclientupdate)
-    - [Helpers](#helpers)
-        - [`LightClientMemory`](#lightclientmemory)
-        - [`get_persistent_committee_pubkeys_and_balances`](#get_persistent_committee_pubkeys_and_balances)
-    - [Light client state updates](#light-client-state-updates)
-    - [Data overhead](#data-overhead)

+- [Introduction](#introduction)
+- [Custom types](#custom-types)
+- [Constants](#constants)
+- [Containers](#containers)
+  - [`LightClientUpdate`](#lightclientupdate)
+- [Helpers](#helpers)
+  - [`LightClientMemory`](#lightclientmemory)
+  - [`get_persistent_committee_pubkeys_and_balances`](#get_persistent_committee_pubkeys_and_balances)
+- [Light client state updates](#light-client-state-updates)
+- [Data overhead](#data-overhead)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
--- a/specs/networking/p2p-interface.md
+++ b/specs/networking/p2p-interface.md
@ -18,23 +18,88 @@ It consists of four main sections:

 - [Network fundamentals](#network-fundamentals)
  - [Transport](#transport)
+      - [Interop](#interop)
+      - [Mainnet](#mainnet)
  - [Encryption and identification](#encryption-and-identification)
-  - [Protocol negotiation](#protocol-negotiation)
+      - [Interop](#interop-1)
+      - [Mainnet](#mainnet-1)
+  - [Protocol Negotiation](#protocol-negotiation)
+      - [Interop](#interop-2)
+      - [Mainnet](#mainnet-2)
  - [Multiplexing](#multiplexing)
 - [Eth2 network interaction domains](#eth2-network-interaction-domains)
  - [Configuration](#configuration)
  - [The gossip domain: gossipsub](#the-gossip-domain-gossipsub)
+    - [Topics and messages](#topics-and-messages)
+      - [Global topics](#global-topics)
+      - [Attestation subnets](#attestation-subnets)
+      - [Interop](#interop-3)
+      - [Mainnet](#mainnet-3)
+    - [Encodings](#encodings)
+      - [Interop](#interop-4)
+      - [Mainnet](#mainnet-4)
  - [The Req/Resp domain](#the-reqresp-domain)
+    - [Protocol identification](#protocol-identification)
+    - [Req/Resp interaction](#reqresp-interaction)
+      - [Requesting side](#requesting-side)
+      - [Responding side](#responding-side)
+    - [Encoding strategies](#encoding-strategies)
+      - [SSZ-encoding strategy (with or without Snappy)](#ssz-encoding-strategy-with-or-without-snappy)
+    - [Messages](#messages)
+      - [Status](#status)
+      - [Goodbye](#goodbye)
+      - [BeaconBlocksByRange](#beaconblocksbyrange)
+      - [BeaconBlocksByRoot](#beaconblocksbyroot)
  - [The discovery domain: discv5](#the-discovery-domain-discv5)
+    - [Integration into libp2p stacks](#integration-into-libp2p-stacks)
+    - [ENR structure](#enr-structure)
+      - [Interop](#interop-5)
+      - [Mainnet](#mainnet-5)
+    - [Topic advertisement](#topic-advertisement)
+      - [Interop](#interop-6)
+      - [Mainnet](#mainnet-6)
 - [Design decision rationale](#design-decision-rationale)
  - [Transport](#transport-1)
+    - [Why are we defining specific transports?](#why-are-we-defining-specific-transports)
+    - [Can clients support other transports/handshakes than the ones mandated by the spec?](#can-clients-support-other-transportshandshakes-than-the-ones-mandated-by-the-spec)
+    - [What are the advantages of using TCP/QUIC/Websockets?](#what-are-the-advantages-of-using-tcpquicwebsockets)
+    - [Why do we not just support a single transport?](#why-do-we-not-just-support-a-single-transport)
+    - [Why are we not using QUIC for mainnet from the start?](#why-are-we-not-using-quic-for-mainnet-from-the-start)
  - [Multiplexing](#multiplexing-1)
-  - [Protocol negotiation](#protocol-negotiation-1)
+    - [Why are we using mplex/yamux?](#why-are-we-using-mplexyamux)
+  - [Protocol Negotiation](#protocol-negotiation-1)
+    - [When is multiselect 2.0 due and why are we using it for mainnet?](#when-is-multiselect-20-due-and-why-are-we-using-it-for-mainnet)
+    - [What is the difference between connection-level and stream-level protocol negotiation?](#what-is-the-difference-between-connection-level-and-stream-level-protocol-negotiation)
  - [Encryption](#encryption)
+    - [Why are we using SecIO for interop? Why not for mainnet?](#why-are-we-using-secio-for-interop-why-not-for-mainnet)
+    - [Why are we using Noise/TLS 1.3 for mainnet?](#why-are-we-using-noisetls-13-for-mainnet)
+    - [Why are we using encryption at all?](#why-are-we-using-encryption-at-all)
+    - [Will mainnnet networking be untested when it launches?](#will-mainnnet-networking-be-untested-when-it-launches)
  - [Gossipsub](#gossipsub)
+    - [Why are we using a pub/sub algorithm for block and attestation propagation?](#why-are-we-using-a-pubsub-algorithm-for-block-and-attestation-propagation)
+    - [Why are we using topics to segregate encodings, yet only support one encoding?](#why-are-we-using-topics-to-segregate-encodings-yet-only-support-one-encoding)
+    - [How do we upgrade gossip channels (e.g. changes in encoding, compression)?](#how-do-we-upgrade-gossip-channels-eg-changes-in-encoding-compression)
+    - [Why must all clients use the same gossip topic instead of one negotiated between each peer pair?](#why-must-all-clients-use-the-same-gossip-topic-instead-of-one-negotiated-between-each-peer-pair)
+    - [Why are the topics strings and not hashes?](#why-are-the-topics-strings-and-not-hashes)
+    - [Why are there `ATTESTATION_SUBNET_COUNT` attestation subnets?](#why-are-there-attestation_subnet_count-attestation-subnets)
+    - [Why are attestations limited to be broadcast on gossip channels within `SLOTS_PER_EPOCH` slots?](#why-are-attestations-limited-to-be-broadcast-on-gossip-channels-within-slots_per_epoch-slots)
+    - [Why are aggregate attestations broadcast to the global topic as `AggregateAndProof`s rather than just as `Attestation`s?](#why-are-aggregate-attestations-broadcast-to-the-global-topic-as-aggregateandproofs-rather-than-just-as-attestations)
+    - [Why are we sending entire objects in the pubsub and not just hashes?](#why-are-we-sending-entire-objects-in-the-pubsub-and-not-just-hashes)
+    - [Should clients gossip blocks if they *cannot* validate the proposer signature due to not yet being synced, not knowing the head block, etc?](#should-clients-gossip-blocks-if-they-cannot-validate-the-proposer-signature-due-to-not-yet-being-synced-not-knowing-the-head-block-etc)
+    - [How are we going to discover peers in a gossipsub topic?](#how-are-we-going-to-discover-peers-in-a-gossipsub-topic)
  - [Req/Resp](#reqresp)
+    - [Why segregate requests into dedicated protocol IDs?](#why-segregate-requests-into-dedicated-protocol-ids)
+    - [Why are messages length-prefixed with a protobuf varint in the SSZ-encoding?](#why-are-messages-length-prefixed-with-a-protobuf-varint-in-the-ssz-encoding)
+    - [Why do we version protocol strings with ordinals instead of semver?](#why-do-we-version-protocol-strings-with-ordinals-instead-of-semver)
+    - [Why is it called Req/Resp and not RPC?](#why-is-it-called-reqresp-and-not-rpc)
  - [Discovery](#discovery)
+    - [Why are we using discv5 and not libp2p Kademlia DHT?](#why-are-we-using-discv5-and-not-libp2p-kademlia-dht)
+    - [What is the difference between an ENR and a multiaddr, and why are we using ENRs?](#what-is-the-difference-between-an-enr-and-a-multiaddr-and-why-are-we-using-enrs)
  - [Compression/Encoding](#compressionencoding)
+    - [Why are we using SSZ for encoding?](#why-are-we-using-ssz-for-encoding)
+    - [Why are we compressing, and at which layers?](#why-are-we-compressing-and-at-which-layers)
+    - [Why are using Snappy for compression?](#why-are-using-snappy-for-compression)
+    - [Can I get access to unencrypted bytes on the wire for debugging purposes?](#can-i-get-access-to-unencrypted-bytes-on-the-wire-for-debugging-purposes)
 - [libp2p implementations matrix](#libp2p-implementations-matrix)

 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
@ -356,7 +421,7 @@ The fields are, as seen by the client at the time of sending the message:
 - `head_fork_version`: The beacon_state `Fork` version.
 - `finalized_root`: `state.finalized_checkpoint.root` for the state corresponding to the head block.
 - `finalized_epoch`: `state.finalized_checkpoint.epoch` for the state corresponding to the head block.
- `head_root`: The signing root of the current head block.
+- `head_root`: The hash_tree_root root of the current head block.
 - `head_slot`: The slot of the block corresponding to the `head_root`.

 The dialing client MUST send a `Status` request upon connection.
@ -567,7 +632,7 @@ Conscious of that, the libp2p community conceptualized [mplex](https://github.co

 Overlay multiplexers are not necessary with QUIC since the protocol provides native multiplexing, but they need to be layered atop TCP, WebSockets, and other transports that lack such support.

-## Protocol negotiation
+## Protocol Negotiation

 ### When is multiselect 2.0 due and why are we using it for mainnet?

--- a/specs/simple-serialize.md
+++ b/specs/simple-serialize.md
@ -4,30 +4,32 @@

 ## Table of contents
 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [SimpleSerialize (SSZ)](#simpleserialize-ssz)
-    - [Table of contents](#table-of-contents)
-    - [Constants](#constants)
-    - [Typing](#typing)
-        - [Basic types](#basic-types)
-        - [Composite types](#composite-types)
-        - [Variable-size and fixed-size](#variable-size-and-fixed-size)
-        - [Aliases](#aliases)
-        - [Default values](#default-values)
-            - [`is_zero`](#is_zero)
-        - [Illegal types](#illegal-types)
-    - [Serialization](#serialization)
-        - [`uintN`](#uintn)
-        - [`boolean`](#boolean)
-        - [`null`](#null)
-        - [`Bitvector[N]`](#bitvectorn)
-        - [`Bitlist[N]`](#bitlistn)
-        - [Vectors, containers, lists, unions](#vectors-containers-lists-unions)
-    - [Deserialization](#deserialization)
-    - [Merkleization](#merkleization)
-    - [Summaries and expansions](#summaries-and-expansions)
-    - [Implementations](#implementations)

+- [Constants](#constants)
+- [Typing](#typing)
+  - [Basic types](#basic-types)
+  - [Composite types](#composite-types)
+  - [Variable-size and fixed-size](#variable-size-and-fixed-size)
+  - [Aliases](#aliases)
+  - [Default values](#default-values)
+    - [`is_zero`](#is_zero)
+  - [Illegal types](#illegal-types)
+- [Serialization](#serialization)
+  - [`uintN`](#uintn)
+  - [`boolean`](#boolean)
+  - [`null`](#null)
+  - [`Bitvector[N]`](#bitvectorn)
+  - [`Bitlist[N]`](#bitlistn)
+  - [Vectors, containers, lists, unions](#vectors-containers-lists-unions)
+- [Deserialization](#deserialization)
+- [Merkleization](#merkleization)
+- [Summaries and expansions](#summaries-and-expansions)
+- [Implementations](#implementations)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Constants
--- a/specs/test_formats/ssz_generic/README.md
+++ b/specs/test_formats/ssz_generic/README.md
@ -37,7 +37,7 @@ Valid has 3 parts: `meta.yaml`, `serialized.ssz`, `value.yaml`

 ### `meta.yaml`

-Valid ssz objects can have a hash-tree-root, and for some types also a signing-root.
+Valid ssz objects can have a hash-tree-root.
 The expected roots are encoded into the metadata yaml:

 ```yaml
@ -61,7 +61,6 @@ The conditions are the same for each type:
 - Encoding: After encoding the given `value` object, the output should match `serialized`.
 - Decoding: After decoding the given `serialized` bytes, it should match the `value` object. 
 - Hash-tree-root: the root should match the root declared in the metadata.
- Signing-root: if present in metadata, the signing root of the object should match the container.

 ## `invalid`

--- a/specs/validator/0_beacon-chain-validator.md
+++ b/specs/validator/0_beacon-chain-validator.md
@ -5,61 +5,64 @@
 ## Table of contents

 <!-- TOC -->
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Ethereum 2.0 Phase 0 -- Honest Validator](#ethereum-20-phase-0----honest-validator)
-    - [Table of contents](#table-of-contents)
-    - [Introduction](#introduction)
-    - [Prerequisites](#prerequisites)
-    - [Constants](#constants)
-        - [Misc](#misc)
-    - [Becoming a validator](#becoming-a-validator)
-        - [Initialization](#initialization)
-            - [BLS public key](#bls-public-key)
-            - [BLS withdrawal key](#bls-withdrawal-key)
-        - [Submit deposit](#submit-deposit)
-        - [Process deposit](#process-deposit)
-        - [Validator index](#validator-index)
-        - [Activation](#activation)
-    - [Validator assignments](#validator-assignments)
-        - [Lookahead](#lookahead)
-    - [Beacon chain responsibilities](#beacon-chain-responsibilities)
-        - [Block proposal](#block-proposal)
-            - [Block header](#block-header)
-                - [Slot](#slot)
-                - [Parent root](#parent-root)
-                - [State root](#state-root)
-                - [Randao reveal](#randao-reveal)
-                - [Eth1 Data](#eth1-data)
-                - [Signature](#signature)
-            - [Block body](#block-body)
-                - [Proposer slashings](#proposer-slashings)
-                - [Attester slashings](#attester-slashings)
-                - [Attestations](#attestations)
-                - [Deposits](#deposits)
-                - [Voluntary exits](#voluntary-exits)
-        - [Attesting](#attesting)
-            - [Attestation data](#attestation-data)
-                - [General](#general)
-                - [LMD GHOST vote](#lmd-ghost-vote)
-                - [FFG vote](#ffg-vote)
-            - [Construct attestation](#construct-attestation)
-                - [Data](#data)
-                - [Aggregation bits](#aggregation-bits)
-                - [Aggregate signature](#aggregate-signature)
-            - [Broadcast attestation](#broadcast-attestation)
-        - [Attestation aggregation](#attestation-aggregation)
-            - [Aggregation selection](#aggregation-selection)
-            - [Construct aggregate](#construct-aggregate)
-                - [Data](#data-1)
-                - [Aggregation bits](#aggregation-bits-1)
-                - [Aggregate signature](#aggregate-signature-1)
-            - [Broadcast aggregate](#broadcast-aggregate)
-                - [`AggregateAndProof`](#aggregateandproof)
-    - [Phase 0 attestation subnet stability](#phase-0-attestation-subnet-stability)
-    - [How to avoid slashing](#how-to-avoid-slashing)
-        - [Proposer slashing](#proposer-slashing)
-        - [Attester slashing](#attester-slashing)

+- [Introduction](#introduction)
+- [Prerequisites](#prerequisites)
+- [Constants](#constants)
+  - [Misc](#misc)
+- [Becoming a validator](#becoming-a-validator)
+  - [Initialization](#initialization)
+    - [BLS public key](#bls-public-key)
+    - [BLS withdrawal key](#bls-withdrawal-key)
+  - [Submit deposit](#submit-deposit)
+  - [Process deposit](#process-deposit)
+  - [Validator index](#validator-index)
+  - [Activation](#activation)
+- [Validator assignments](#validator-assignments)
+  - [Lookahead](#lookahead)
+- [Beacon chain responsibilities](#beacon-chain-responsibilities)
+  - [Block proposal](#block-proposal)
+    - [Preparing for a `BeaconBlock`](#preparing-for-a-beaconblock)
+      - [Slot](#slot)
+      - [Parent root](#parent-root)
+    - [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
+      - [Randao reveal](#randao-reveal)
+      - [Eth1 Data](#eth1-data)
+      - [Proposer slashings](#proposer-slashings)
+      - [Attester slashings](#attester-slashings)
+      - [Attestations](#attestations)
+      - [Deposits](#deposits)
+      - [Voluntary exits](#voluntary-exits)
+    - [Packaging into a `SignedBeaconBlock`](#packaging-into-a-signedbeaconblock)
+      - [State root](#state-root)
+      - [Signature](#signature)
+  - [Attesting](#attesting)
+    - [Attestation data](#attestation-data)
+      - [General](#general)
+      - [LMD GHOST vote](#lmd-ghost-vote)
+      - [FFG vote](#ffg-vote)
+    - [Construct attestation](#construct-attestation)
+      - [Data](#data)
+      - [Aggregation bits](#aggregation-bits)
+      - [Aggregate signature](#aggregate-signature)
+    - [Broadcast attestation](#broadcast-attestation)
+  - [Attestation aggregation](#attestation-aggregation)
+    - [Aggregation selection](#aggregation-selection)
+    - [Construct aggregate](#construct-aggregate)
+      - [Data](#data-1)
+      - [Aggregation bits](#aggregation-bits-1)
+      - [Aggregate signature](#aggregate-signature-1)
+    - [Broadcast aggregate](#broadcast-aggregate)
+      - [`AggregateAndProof`](#aggregateandproof)
+- [Phase 0 attestation subnet stability](#phase-0-attestation-subnet-stability)
+- [How to avoid slashing](#how-to-avoid-slashing)
+  - [Proposer slashing](#proposer-slashing)
+  - [Attester slashing](#attester-slashing)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->

 ## Introduction
--- a/test_libs/pyspec/eth2spec/test/fork_choice/test_get_head.py
+++ b/test_libs/pyspec/eth2spec/test/fork_choice/test_get_head.py
@ -1,7 +1,11 @@
 from eth2spec.test.context import with_all_phases, spec_state_test
 from eth2spec.test.helpers.attestations import get_valid_attestation
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot
-from eth2spec.test.helpers.state import state_transition_and_sign_block
+from eth2spec.test.helpers.state import (
+    next_epoch,
+    next_epoch_with_attestations,
+    state_transition_and_sign_block,
+)


 def add_block_to_store(spec, store, signed_block):
@ -112,3 +116,79 @@ def test_shorter_chain_but_heavier_weight(spec, state):
    add_attestation_to_store(spec, store, short_attestation)

    assert spec.get_head(store) == spec.hash_tree_root(short_block)
+
+
+@with_all_phases
+@spec_state_test
+def test_filtered_block_tree(spec, state):
+    # Initialization
+    genesis_state_root = state.hash_tree_root()
+    store = spec.get_genesis_store(state)
+    genesis_block = spec.BeaconBlock(state_root=genesis_state_root)
+
+    # transition state past initial couple of epochs
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
+    assert spec.get_head(store) == spec.hash_tree_root(genesis_block)
+
+    # fill in attestations for entire epoch, justifying the recent epoch
+    prev_state, signed_blocks, state = next_epoch_with_attestations(spec, state, True, False)
+    attestations = [
+        attestation for signed_block in signed_blocks
+        for attestation in signed_block.message.body.attestations
+    ]
+    assert state.current_justified_checkpoint.epoch > prev_state.current_justified_checkpoint.epoch
+
+    # tick time forward and add blocks and attestations to store
+    current_time = state.slot * spec.SECONDS_PER_SLOT + store.genesis_time
+    spec.on_tick(store, current_time)
+    for signed_block in signed_blocks:
+        spec.on_block(store, signed_block)
+    for attestation in attestations:
+        spec.on_attestation(store, attestation)
+
+    assert store.justified_checkpoint == state.current_justified_checkpoint
+
+    # the last block in the branch should be the head
+    expected_head_root = spec.hash_tree_root(signed_blocks[-1].message)
+    assert spec.get_head(store) == expected_head_root
+
+    #
+    # create branch containing the justified block but not containing enough on
+    # chain votes to justify that block
+    #
+
+    # build a chain without attestations off of previous justified block
+    non_viable_state = store.block_states[store.justified_checkpoint.root].copy()
+
+    # ensure that next wave of votes are for future epoch
+    next_epoch(spec, non_viable_state)
+    next_epoch(spec, non_viable_state)
+    next_epoch(spec, non_viable_state)
+    assert spec.get_current_epoch(non_viable_state) > store.justified_checkpoint.epoch
+
+    # create rogue block that will be attested to in this non-viable branch
+    rogue_block = build_empty_block_for_next_slot(spec, non_viable_state)
+    signed_rogue_block = state_transition_and_sign_block(spec, non_viable_state, rogue_block)
+
+    # create an epoch's worth of attestations for the rogue block
+    next_epoch(spec, non_viable_state)
+    attestations = []
+    for i in range(spec.SLOTS_PER_EPOCH):
+        slot = rogue_block.slot + i
+        for index in range(spec.get_committee_count_at_slot(non_viable_state, slot)):
+            attestation = get_valid_attestation(spec, non_viable_state, rogue_block.slot + i, index)
+            attestations.append(attestation)
+
+    # tick time forward to be able to include up to the latest attestation
+    current_time = (attestations[-1].data.slot + 1) * spec.SECONDS_PER_SLOT + store.genesis_time
+    spec.on_tick(store, current_time)
+
+    # include rogue block and associated attestations in the store
+    spec.on_block(store, signed_rogue_block)
+    for attestation in attestations:
+        spec.on_attestation(store, attestation)
+
+    # ensure that get_head still returns the head from the previous branch
+    assert spec.get_head(store) == expected_head_root
--- a/test_libs/pyspec/eth2spec/test/fork_choice/test_on_attestation.py
+++ b/test_libs/pyspec/eth2spec/test/fork_choice/test_on_attestation.py
@ -84,6 +84,29 @@ def test_on_attestation_past_epoch(spec, state):
    run_on_attestation(spec, state, store, attestation, False)


+@with_all_phases
+@spec_state_test
+def test_on_attestation_mismatched_target_and_slot(spec, state):
+    store = spec.get_genesis_store(state)
+    spec.on_tick(store, store.time + spec.SECONDS_PER_SLOT * spec.SLOTS_PER_EPOCH)
+
+    block = build_empty_block_for_next_slot(spec, state)
+    signed_block = state_transition_and_sign_block(spec, state, block)
+
+    # store block in store
+    spec.on_block(store, signed_block)
+
+    attestation = get_valid_attestation(spec, state, slot=block.slot)
+    attestation.data.target.epoch += 1
+    sign_attestation(spec, state, attestation)
+
+    assert attestation.data.target.epoch == spec.GENESIS_EPOCH + 1
+    assert spec.compute_epoch_at_slot(attestation.data.slot) == spec.GENESIS_EPOCH
+    assert spec.compute_epoch_at_slot(spec.get_current_slot(store)) == spec.GENESIS_EPOCH + 1
+
+    run_on_attestation(spec, state, store, attestation, False)
+
+
@with_all_phases
@spec_state_test
 def test_on_attestation_target_not_in_store(spec, state):
--- a/test_libs/pyspec/eth2spec/test/fork_choice/test_on_block.py
+++ b/test_libs/pyspec/eth2spec/test/fork_choice/test_on_block.py
@ -168,7 +168,7 @@ def test_on_block_update_justified_checkpoint_within_safe_slots(spec, state):

@with_all_phases
@spec_state_test
-def test_on_block_outside_safe_slots_and_old_block(spec, state):
+def test_on_block_outside_safe_slots_and_multiple_better_justified(spec, state):
    # Initialization
    store = spec.get_genesis_store(state)
    time = 100
@ -187,20 +187,30 @@ def test_on_block_outside_safe_slots_and_old_block(spec, state):
    just_block.slot = spec.compute_start_slot_at_epoch(store.justified_checkpoint.epoch)
    store.blocks[just_block.hash_tree_root()] = just_block

-    # Mock the justified checkpoint
-    just_state = store.block_states[last_block_root]
-    new_justified = spec.Checkpoint(
-        epoch=just_state.current_justified_checkpoint.epoch + 1,
-        root=just_block.hash_tree_root(),
-    )
-    just_state.current_justified_checkpoint = new_justified
-
-    block = build_empty_block_for_next_slot(spec, just_state)
-    signed_block = state_transition_and_sign_block(spec, deepcopy(just_state), block)
-
+    # Step time past safe slots
    spec.on_tick(store, store.time + spec.SAFE_SLOTS_TO_UPDATE_JUSTIFIED * spec.SECONDS_PER_SLOT)
    assert spec.get_current_slot(store) % spec.SLOTS_PER_EPOCH >= spec.SAFE_SLOTS_TO_UPDATE_JUSTIFIED
-    run_on_block(spec, store, signed_block)

-    assert store.justified_checkpoint != new_justified
-    assert store.best_justified_checkpoint == new_justified
+    previously_justified = store.justified_checkpoint
+
+    # Add a series of new blocks with "better" justifications
+    best_justified_checkpoint = spec.Checkpoint(epoch=0)
+    for i in range(3, 0, -1):
+        just_state = store.block_states[last_block_root]
+        new_justified = spec.Checkpoint(
+            epoch=previously_justified.epoch + i,
+            root=just_block.hash_tree_root(),
+        )
+        if new_justified.epoch > best_justified_checkpoint.epoch:
+            best_justified_checkpoint = new_justified
+
+        just_state.current_justified_checkpoint = new_justified
+
+        block = build_empty_block_for_next_slot(spec, just_state)
+        signed_block = state_transition_and_sign_block(spec, deepcopy(just_state), block)
+
+        run_on_block(spec, store, signed_block)
+
+    assert store.justified_checkpoint == previously_justified
+    # ensure the best from the series was stored
+    assert store.best_justified_checkpoint == best_justified_checkpoint
--- a/test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_attestation.py
+++ b/test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_attestation.py
@ -177,6 +177,20 @@ def test_invalid_index(spec, state):
    yield from run_attestation_processing(spec, state, attestation, False)


+@with_all_phases
+@spec_state_test
+def test_mismatched_target_and_slot(spec, state):
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
+    attestation = get_valid_attestation(spec, state)
+    attestation.data.slot = attestation.data.slot - spec.SLOTS_PER_EPOCH
+
+    sign_attestation(spec, state, attestation)
+
+    yield from run_attestation_processing(spec, state, attestation, False)
+
+
@with_all_phases
@spec_state_test
 def test_old_target_epoch(spec, state):
--- a/test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_attester_slashing.py
+++ b/test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_attester_slashing.py
@ -252,6 +252,76 @@ def test_att2_bad_replaced_index(spec, state):
    yield from run_attester_slashing_processing(spec, state, attester_slashing, False)


+@with_all_phases
+@spec_state_test
+@always_bls
+def test_att1_duplicate_index_normal_signed(spec, state):
+    attester_slashing = get_valid_attester_slashing(spec, state, signed_1=False, signed_2=True)
+
+    indices = attester_slashing.attestation_1.attesting_indices
+    indices.pop(1)  # remove an index, make room for the additional duplicate index.
+    attester_slashing.attestation_1.attesting_indices = sorted(indices)
+
+    # sign it, the signature will be valid for a single occurence. If the transition accidentally ignores the duplicate.
+    sign_indexed_attestation(spec, state, attester_slashing.attestation_1)
+
+    indices.append(indices[0])  # add one of the indices a second time
+    attester_slashing.attestation_1.attesting_indices = sorted(indices)
+
+    # it will just appear normal, unless the double index is spotted
+    yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
+
+
+@with_all_phases
+@spec_state_test
+@always_bls
+def test_att2_duplicate_index_normal_signed(spec, state):
+    attester_slashing = get_valid_attester_slashing(spec, state, signed_1=True, signed_2=False)
+
+    indices = attester_slashing.attestation_2.attesting_indices
+    indices.pop(2)  # remove an index, make room for the additional duplicate index.
+    attester_slashing.attestation_2.attesting_indices = sorted(indices)
+
+    # sign it, the signature will be valid for a single occurence. If the transition accidentally ignores the duplicate.
+    sign_indexed_attestation(spec, state, attester_slashing.attestation_2)
+
+    indices.append(indices[1])  # add one of the indices a second time
+    attester_slashing.attestation_2.attesting_indices = sorted(indices)
+
+    # it will just appear normal, unless the double index is spotted
+    yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
+
+
+@with_all_phases
+@spec_state_test
+@always_bls
+def test_att1_duplicate_index_double_signed(spec, state):
+    attester_slashing = get_valid_attester_slashing(spec, state, signed_1=False, signed_2=True)
+
+    indices = attester_slashing.attestation_1.attesting_indices
+    indices.pop(1)  # remove an index, make room for the additional duplicate index.
+    indices.append(indices[2])  # add one of the indices a second time
+    attester_slashing.attestation_1.attesting_indices = sorted(indices)
+    sign_indexed_attestation(spec, state, attester_slashing.attestation_1)  # will have one attester signing it double
+
+    yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
+
+
+@with_all_phases
+@spec_state_test
+@always_bls
+def test_att2_duplicate_index_double_signed(spec, state):
+    attester_slashing = get_valid_attester_slashing(spec, state, signed_1=True, signed_2=False)
+
+    indices = attester_slashing.attestation_2.attesting_indices
+    indices.pop(1)  # remove an index, make room for the additional duplicate index.
+    indices.append(indices[2])  # add one of the indices a second time
+    attester_slashing.attestation_2.attesting_indices = sorted(indices)
+    sign_indexed_attestation(spec, state, attester_slashing.attestation_2)  # will have one attester signing it double
+
+    yield from run_attester_slashing_processing(spec, state, attester_slashing, False)
+
+
@with_all_phases
@spec_state_test
 def test_unsorted_att_1(spec, state):
--- a/test_libs/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_registry_updates.py
+++ b/test_libs/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_registry_updates.py
@ -17,24 +17,80 @@ def mock_deposit(spec, state, index):

@with_all_phases
@spec_state_test
-def test_activation(spec, state):
+def test_add_to_activation_queue(spec, state):
+    # move past first two irregular epochs wrt finality
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
    index = 0
    mock_deposit(spec, state, index)

-    for _ in range(spec.MAX_SEED_LOOKAHEAD + 1):
-        next_epoch(spec, state)
+    yield from run_process_registry_updates(spec, state)
+
+    # validator moved into queue
+    assert state.validators[index].activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
+    assert state.validators[index].activation_epoch == spec.FAR_FUTURE_EPOCH
+    assert not spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))
+
+
+@with_all_phases
+@spec_state_test
+def test_activation_queue_to_activated_if_finalized(spec, state):
+    # move past first two irregular epochs wrt finality
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
+    index = 0
+    mock_deposit(spec, state, index)
+
+    # mock validator as having been in queue since latest finalized
+    state.finalized_checkpoint.epoch = spec.get_current_epoch(state) - 1
+    state.validators[index].activation_eligibility_epoch = state.finalized_checkpoint.epoch
+
+    assert not spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))

    yield from run_process_registry_updates(spec, state)

+    # validator activated for future epoch
    assert state.validators[index].activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
    assert state.validators[index].activation_epoch != spec.FAR_FUTURE_EPOCH
-    assert spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))
+    assert not spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))
+    assert spec.is_active_validator(
+        state.validators[index],
+        spec.compute_activation_exit_epoch(spec.get_current_epoch(state))
+    )
+
+
+@with_all_phases
+@spec_state_test
+def test_activation_queue_no_activation_no_finality(spec, state):
+    # move past first two irregular epochs wrt finality
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
+    index = 0
+    mock_deposit(spec, state, index)
+
+    # mock validator as having been in queue only after latest finalized
+    state.finalized_checkpoint.epoch = spec.get_current_epoch(state) - 1
+    state.validators[index].activation_eligibility_epoch = state.finalized_checkpoint.epoch + 1
+
+    assert not spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))
+
+    yield from run_process_registry_updates(spec, state)
+
+    # validator not activated
+    assert state.validators[index].activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
+    assert state.validators[index].activation_epoch == spec.FAR_FUTURE_EPOCH


@with_all_phases
@spec_state_test
 def test_activation_queue_sorting(spec, state):
-    mock_activations = 10
+    churn_limit = spec.get_validator_churn_limit(state)
+
+    # try to activate more than the per-epoch churn linmit
+    mock_activations = churn_limit * 2

    epoch = spec.get_current_epoch(state)
    for i in range(mock_activations):
@ -44,9 +100,9 @@ def test_activation_queue_sorting(spec, state):
    # give the last priority over the others
    state.validators[mock_activations - 1].activation_eligibility_epoch = epoch

-    # make sure we are hitting the churn
-    churn_limit = spec.get_validator_churn_limit(state)
-    assert mock_activations > churn_limit
+    # move state forward and finalize to allow for activations
+    state.slot += spec.SLOTS_PER_EPOCH * 3
+    state.finalized_checkpoint.epoch = epoch + 1

    yield from run_process_registry_updates(spec, state)

@ -63,6 +119,38 @@ def test_activation_queue_sorting(spec, state):
    assert state.validators[churn_limit - 2].activation_epoch != spec.FAR_FUTURE_EPOCH


+@with_all_phases
+@spec_state_test
+def test_activation_queue_efficiency(spec, state):
+    churn_limit = spec.get_validator_churn_limit(state)
+    mock_activations = churn_limit * 2
+
+    epoch = spec.get_current_epoch(state)
+    for i in range(mock_activations):
+        mock_deposit(spec, state, i)
+        state.validators[i].activation_eligibility_epoch = epoch + 1
+
+    # move state forward and finalize to allow for activations
+    state.slot += spec.SLOTS_PER_EPOCH * 3
+    state.finalized_checkpoint.epoch = epoch + 1
+
+    # Run first registry update. Do not yield test vectors
+    for _ in run_process_registry_updates(spec, state):
+        pass
+
+    # Half should churn in first run of registry update
+    for i in range(mock_activations):
+        if i < mock_activations // 2:
+            assert state.validators[i].activation_epoch < spec.FAR_FUTURE_EPOCH
+        else:
+            assert state.validators[i].activation_epoch == spec.FAR_FUTURE_EPOCH
+
+    # Second half should churn in second run of registry update
+    yield from run_process_registry_updates(spec, state)
+    for i in range(mock_activations):
+        assert state.validators[i].activation_epoch < spec.FAR_FUTURE_EPOCH
+
+
@with_all_phases
@spec_state_test
 def test_ejection(spec, state):
@ -73,13 +161,87 @@ def test_ejection(spec, state):
    # Mock an ejection
    state.validators[index].effective_balance = spec.EJECTION_BALANCE

-    for _ in range(spec.MAX_SEED_LOOKAHEAD + 1):
-        next_epoch(spec, state)
-
    yield from run_process_registry_updates(spec, state)

    assert state.validators[index].exit_epoch != spec.FAR_FUTURE_EPOCH
+    assert spec.is_active_validator(state.validators[index], spec.get_current_epoch(state))
    assert not spec.is_active_validator(
        state.validators[index],
-        spec.get_current_epoch(state),
+        spec.compute_activation_exit_epoch(spec.get_current_epoch(state))
+    )
+
+
+@with_all_phases
+@spec_state_test
+def test_ejection_past_churn_limit(spec, state):
+    churn_limit = spec.get_validator_churn_limit(state)
+
+    # try to eject more than per-epoch churn limit
+    mock_ejections = churn_limit * 3
+
+    for i in range(mock_ejections):
+        state.validators[i].effective_balance = spec.EJECTION_BALANCE
+
+    expected_ejection_epoch = spec.compute_activation_exit_epoch(spec.get_current_epoch(state))
+
+    yield from run_process_registry_updates(spec, state)
+
+    for i in range(mock_ejections):
+        # first third ejected in normal speed
+        if i < mock_ejections // 3:
+            assert state.validators[i].exit_epoch == expected_ejection_epoch
+        # second thirdgets delayed by 1 epoch
+        elif mock_ejections // 3 <= i < mock_ejections * 2 // 3:
+            assert state.validators[i].exit_epoch == expected_ejection_epoch + 1
+        # second thirdgets delayed by 2 epochs
+        else:
+            assert state.validators[i].exit_epoch == expected_ejection_epoch + 2
+
+
+@with_all_phases
+@spec_state_test
+def test_activation_queue_activation_and_ejection(spec, state):
+    # move past first two irregular epochs wrt finality
+    next_epoch(spec, state)
+    next_epoch(spec, state)
+
+    # ready for entrance into activation queue
+    activation_queue_index = 0
+    mock_deposit(spec, state, activation_queue_index)
+
+    # ready for activation
+    activation_index = 1
+    mock_deposit(spec, state, activation_index)
+    state.finalized_checkpoint.epoch = spec.get_current_epoch(state) - 1
+    state.validators[activation_index].activation_eligibility_epoch = state.finalized_checkpoint.epoch
+
+    # ready for ejection
+    ejection_index = 2
+    state.validators[ejection_index].effective_balance = spec.EJECTION_BALANCE
+
+    yield from run_process_registry_updates(spec, state)
+
+    # validator moved into activation queue
+    validator = state.validators[activation_queue_index]
+    assert validator.activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
+    assert validator.activation_epoch == spec.FAR_FUTURE_EPOCH
+    assert not spec.is_active_validator(validator, spec.get_current_epoch(state))
+
+    # validator activated for future epoch
+    validator = state.validators[activation_index]
+    assert validator.activation_eligibility_epoch != spec.FAR_FUTURE_EPOCH
+    assert validator.activation_epoch != spec.FAR_FUTURE_EPOCH
+    assert not spec.is_active_validator(validator, spec.get_current_epoch(state))
+    assert spec.is_active_validator(
+        validator,
+        spec.compute_activation_exit_epoch(spec.get_current_epoch(state))
+    )
+
+    # validator ejected for future epoch
+    validator = state.validators[ejection_index]
+    assert validator.exit_epoch != spec.FAR_FUTURE_EPOCH
+    assert spec.is_active_validator(validator, spec.get_current_epoch(state))
+    assert not spec.is_active_validator(
+        validator,
+        spec.compute_activation_exit_epoch(spec.get_current_epoch(state))
    )
--- a/test_libs/pyspec/eth2spec/test/sanity/test_blocks.py
+++ b/test_libs/pyspec/eth2spec/test/sanity/test_blocks.py
@ -3,7 +3,7 @@ from copy import deepcopy
 from eth2spec.utils.ssz.ssz_impl import hash_tree_root
 from eth2spec.utils.bls import bls_sign

-from eth2spec.test.helpers.state import get_balance, state_transition_and_sign_block
+from eth2spec.test.helpers.state import get_balance, state_transition_and_sign_block, next_slot
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot, build_empty_block, sign_block, \
    transition_unsigned_block
 from eth2spec.test.helpers.keys import privkeys, pubkeys
@ -253,6 +253,58 @@ def test_attester_slashing(spec, state):
    )


+@with_all_phases
+@spec_state_test
+def test_proposer_after_inactive_index(spec, state):
+    # disable some low validator index to check after for
+    inactive_index = 10
+    state.validators[inactive_index].exit_epoch = spec.get_current_epoch(state)
+
+    # skip forward, get brand new proposers
+    state.slot = spec.SLOTS_PER_EPOCH * 2
+    block = build_empty_block_for_next_slot(spec, state)
+    state_transition_and_sign_block(spec, state, block)
+
+    while True:
+        next_slot(spec, state)
+        proposer_index = spec.get_beacon_proposer_index(state)
+        if proposer_index > inactive_index:
+            # found a proposer that has a higher index than a disabled validator
+            yield 'pre', state
+            # test if the proposer can be recognized correctly after the inactive validator
+            signed_block = state_transition_and_sign_block(spec, state, build_empty_block(spec, state))
+            yield 'blocks', [signed_block]
+            yield 'post', state
+            break
+
+
+@with_all_phases
+@spec_state_test
+def test_high_proposer_index(spec, state):
+    # disable a good amount of validators to make the active count lower, for a faster test
+    current_epoch = spec.get_current_epoch(state)
+    for i in range(len(state.validators) // 3):
+        state.validators[i].exit_epoch = current_epoch
+
+    # skip forward, get brand new proposers
+    state.slot = spec.SLOTS_PER_EPOCH * 2
+    block = build_empty_block_for_next_slot(spec, state)
+    state_transition_and_sign_block(spec, state, block)
+
+    active_count = len(spec.get_active_validator_indices(state, current_epoch))
+    while True:
+        next_slot(spec, state)
+        proposer_index = spec.get_beacon_proposer_index(state)
+        if proposer_index >= active_count:
+            # found a proposer that has a higher index than the active validator count
+            yield 'pre', state
+            # test if the proposer can be recognized correctly, even while it has a high index.
+            signed_block = state_transition_and_sign_block(spec, state, build_empty_block(spec, state))
+            yield 'blocks', [signed_block]
+            yield 'post', state
+            break
+
+
@with_all_phases
@spec_state_test
 def test_expected_deposit_in_block(spec, state):
--- a/test_libs/pyspec/requirements-testing.txt
+++ b/test_libs/pyspec/requirements-testing.txt
@ -2,6 +2,6 @@
 pytest>=4.4
 ../config_helpers
 flake8==3.7.7
-mypy==0.701
+mypy==0.750
 pytest-cov
 pytest-xdist