TheVerge: spec draft

specs/_features/verge/beacon-chain.md

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+# The Verge -- The Beacon Chain
+
+## 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 -->
+
+- [Introduction](#introduction)
+- [Custom types](#custom-types)
+- [Preset](#preset)
+  - [Execution](#execution)
+- [Containers](#containers)
+  - [Extended containers](#extended-containers)
+    - [`ExecutionPayload`](#executionpayload)
+    - [`ExecutionPayloadHeader`](#executionpayloadheader)
+  - [New containers](#new-containers)
+    - [`SuffixStateDiff`](#suffixstatediff)
+    - [`StemStateDiff`](#stemstatediff)
+    - [`IPAProof`](#ipaproof)
+    - [`VerkleProof`](#verkleproof)
+    - [`ExecutionWitness`](#executionwitness)
+- [Beacon chain state transition function](#beacon-chain-state-transition-function)
+  - [Execution engine](#execution-engine)
+    - [`notify_new_payload`](#notify_new_payload)
+  - [Block processing](#block-processing)
+    - [Execution payload](#execution-payload)
+      - [`process_execution_payload`](#process_execution_payload)
+- [Testing](#testing)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+<!-- /TOC -->
+
+## Introduction
+
+This upgrade adds transaction execution to the beacon chain as part of the Verge upgrade.
+
+## Custom types
+
+| Name | SSZ equivalent | Description |
+| - | - | - |
+| `StateDiff` | `List[StemStateDiff, MAX_STEMS]` | Only valid if list is sorted by stems |
+| `BanderwagonGroupElement` | `Bytes32` | |
+| `BanderwagonFieldElement` | `Bytes32` | |
+| `Stem` | `Bytes31` | |
+
+## Preset
+
+### Execution
+
+| Name | Value |
+| - | - |
+| `MAX_STEMS` | `2**16` |
+| `MAX_COMMITMENTS_PER_STEM` | `33` |
+| `VERKLE_WIDTH` | `256` |
+| `IPA_PROOF_DEPTH` | `8` |
+
+## Containers
+
+### Extended containers
+
+#### `ExecutionPayload`
+
+```python
+class ExecutionPayload(Container):
+    # Execution block header fields
+    parent_hash: Hash32
+    fee_recipient: ExecutionAddress  # 'beneficiary' in the yellow paper
+    state_root: Bytes32
+    receipts_root: Bytes32
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    prev_randao: Bytes32  # 'difficulty' in the yellow paper
+    block_number: uint64  # 'number' in the yellow paper
+    gas_limit: uint64
+    gas_used: uint64
+    timestamp: uint64
+    extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
+    base_fee_per_gas: uint256
+    block_hash: Hash32  # Hash of execution block
+    # Extra payload field
+    transactions: List[Transaction, MAX_TRANSACTIONS_PER_PAYLOAD]
+    execution_witness: ExecutionWitness  # [New in Verge]
+```
+
+#### `ExecutionPayloadHeader`
+
+```python
+class ExecutionPayloadHeader(Container):
+    # Execution block header fields
+    parent_hash: Hash32
+    fee_recipient: ExecutionAddress
+    state_root: Bytes32
+    receipts_root: Bytes32
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    prev_randao: Bytes32
+    block_number: uint64
+    gas_limit: uint64
+    gas_used: uint64
+    timestamp: uint64
+    extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
+    base_fee_per_gas: uint256
+    block_hash: Hash32  # Hash of execution block
+    transactions_root: Root
+    # Extra payload fields
+    execution_witness_root: Root # [New in Verge]
+```
+
+### New containers
+
+#### `SuffixStateDiff`
+
+```python
+class SuffixStateDiff(Container):
+    suffix: Byte
+    # Null means not currently present
+    current_value: Optional[Bytes32]
+    # Null means value not updated
+    new_value: Optional[Bytes32]
+```
+
+*Note*: on the Kaustinen testnet, `new_value` is ommitted from the container.
+
+#### `StemStateDiff`
+
+```python
+class StemStateDiff(Container):
+    stem: Stem
+    # Valid only if list is sorted by suffixes
+    suffix_diffs: List[SuffixStateDiff, VERKLE_WIDTH]
+```
+
+```python
+# Valid only if list is sorted by stems
+StateDiff = List[StemStateDiff, MAX_STEMS]
+```
+
+#### `IPAProof`
+
+```python
+class IpaProof(Container):
+    cl: Vector[BanderwagonGroupElement, IPA_PROOF_DEPTH]
+    cr: Vector[BanderwagonGroupElement, IPA_PROOF_DEPTH]
+    final_evaluation = BanderwagonFieldElement
+```
+
+#### `VerkleProof`
+
+```python
+class VerkleProof(Container):
+    other_stems: List[Bytes31, MAX_STEMS]
+    depth_extension_present: List[uint8, MAX_STEMS]
+    commitments_by_path: List[BanderwagonGroupElement, MAX_STEMS * MAX_COMMITMENTS_PER_STEM]
+    d: BanderwagonGroupElement
+    ipa_proof: IpaProof
+```
+
+#### `ExecutionWitness`
+
+```python
+class ExecutionWitness(container):
+    state_diff: StateDiff
+    verkle_proof: VerkleProof
+```
+
+## Beacon chain state transition function
+
+### Block processing
+
+#### Execution payload
+
+##### `process_execution_payload`
+
+```python
+def process_execution_payload(state: BeaconState, payload: ExecutionPayload, execution_engine: ExecutionEngine) -> None:
+    # Verify consistency of the parent hash with respect to the previous execution payload header
+    if is_merge_transition_complete(state):
+        assert payload.parent_hash == state.latest_execution_payload_header.block_hash
+    # Verify prev_randao
+    assert payload.prev_randao == get_randao_mix(state, get_current_epoch(state))
+    # Verify timestamp
+    assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
+    # Verify the execution payload is valid
+    assert execution_engine.notify_new_payload(payload)
+    # Cache execution payload header
+    state.latest_execution_payload_header = ExecutionPayloadHeader(
+        parent_hash=payload.parent_hash,
+        fee_recipient=payload.fee_recipient,
+        state_root=payload.state_root,
+        receipts_root=payload.receipts_root,
+        logs_bloom=payload.logs_bloom,
+        prev_randao=payload.prev_randao,
+        block_number=payload.block_number,
+        gas_limit=payload.gas_limit,
+        gas_used=payload.gas_used,
+        timestamp=payload.timestamp,
+        extra_data=payload.extra_data,
+        base_fee_per_gas=payload.base_fee_per_gas,
+        block_hash=payload.block_hash,
+        transactions_root=hash_tree_root(payload.transactions),
+        execution_witness=payload.execution_witness,
+    )
+```
+
+## Testing
+
+TBD

specs/_features/verge/fork.md

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+# The Verge -- Fork Logic
+
+## Table of contents
+
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+
+- [Introduction](#introduction)
+- [Configuration](#configuration)
+- [Helper functions](#helper-functions)
+  - [Misc](#misc)
+    - [Modified `compute_fork_version`](#modified-compute_fork_version)
+- [Fork to the Verge](#fork-to-capella)
+  - [Fork trigger](#fork-trigger)
+  - [Upgrading the state](#upgrading-the-state)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+## Introduction
+
+This document describes the process of the Verge upgrade.
+
+## Configuration
+
+Warning: this configuration is not definitive.
+
+| Name | Value |
+| - | - |
+| `VERGE_FORK_VERSION` | `Version('0x05000000')` |
+| `VERGE_FORK_EPOCH` | `Epoch(18446744073709551615)` **TBD** |
+
+
+## Helper functions
+
+### Misc
+
+#### Modified `compute_fork_version`
+
+```python
+def compute_fork_version(epoch: Epoch) -> Version:
+    """
+    Return the fork version at the given ``epoch``.
+    """
+    if epoch >= VERGE_FORK_EPOCH:
+        return VERGE_FORK_VERSION
+    if epoch >= CAPELLA_FORK_EPOCH:
+        return CAPELLA_FORK_VERSION
+    if epoch >= BELLATRIX_FORK_EPOCH:
+        return BELLATRIX_FORK_VERSION
+    if epoch >= ALTAIR_FORK_EPOCH:
+        return ALTAIR_FORK_VERSION
+    return GENESIS_FORK_VERSION
+```
+
+## Fork to the Verge
+
+### Fork trigger
+
+The fork is triggered at epoch `VERGE_FORK_EPOCH`.
+
+Note that for the pure verge networks, we don't apply `upgrade_to_verge` since it starts with the Verge version logic.
+
+### Upgrading the state
+
+If `state.slot % SLOTS_PER_EPOCH == 0` and `compute_epoch_at_slot(state.slot) == VERGE_FORK_EPOCH`,
+an irregular state change is made to upgrade to the Verge.
+
+The upgrade occurs after the completion of the inner loop of `process_slots` that sets `state.slot` equal to `VERGE_FORK_EPOCH * SLOTS_PER_EPOCH`.
+Care must be taken when transitioning through the fork boundary as implementations will need a modified [state transition function](../phase0/beacon-chain.md#beacon-chain-state-transition-function) that deviates from the Phase 0 document.
+In particular, the outer `state_transition` function defined in the Phase 0 document will not expose the precise fork slot to execute the upgrade in the presence of skipped slots at the fork boundary. Instead, the logic must be within `process_slots`.
+
+```python
+def upgrade_to_verge(pre: capella.BeaconState) -> BeaconState:
+    epoch = capella.get_current_epoch(pre)
+    latest_execution_payload_header = ExecutionPayloadHeader(
+        parent_hash=pre.latest_execution_payload_header.parent_hash,
+        fee_recipient=pre.latest_execution_payload_header.fee_recipient,
+        state_root=pre.latest_execution_payload_header.state_root,
+        receipts_root=pre.latest_execution_payload_header.receipts_root,
+        logs_bloom=pre.latest_execution_payload_header.logs_bloom,
+        prev_randao=pre.latest_execution_payload_header.prev_randao,
+        block_number=pre.latest_execution_payload_header.block_number,
+        gas_limit=pre.latest_execution_payload_header.gas_limit,
+        gas_used=pre.latest_execution_payload_header.gas_used,
+        timestamp=pre.latest_execution_payload_header.timestamp,
+        extra_data=pre.latest_execution_payload_header.extra_data,
+        base_fee_per_gas=pre.latest_execution_payload_header.base_fee_per_gas,
+        block_hash=pre.latest_execution_payload_header.block_hash,
+        transactions_root=pre.latest_execution_payload_header.transactions_root,
+        withdrawals_root=pre.latest_execution_payload_header.withdrawals_root,
+        execution_witness=ExecutionWitness([], []) # New in the Verge
+    )
+    post = BeaconState(
+        # Versioning
+        genesis_time=pre.genesis_time,
+        genesis_validators_root=pre.genesis_validators_root,
+        slot=pre.slot,
+        fork=Fork(
+            previous_version=pre.fork.current_version,
+            current_version=VERGE_FORK_VERSION,
+            epoch=epoch,
+        ),
+        # History
+        latest_block_header=pre.latest_block_header,
+        block_roots=pre.block_roots,
+        state_roots=pre.state_roots,
+        historical_roots=pre.historical_roots,
+        # Eth1
+        eth1_data=pre.eth1_data,
+        eth1_data_votes=pre.eth1_data_votes,
+        eth1_deposit_index=pre.eth1_deposit_index,
+        # Registry
+        validators=pre.validators,
+        balances=pre.balances,
+        # Randomness
+        randao_mixes=pre.randao_mixes,
+        # Slashings
+        slashings=pre.slashings,
+        # Participation
+        previous_epoch_participation=pre.previous_epoch_participation,
+        current_epoch_participation=pre.current_epoch_participation,
+        # Finality
+        justification_bits=pre.justification_bits,
+        previous_justified_checkpoint=pre.previous_justified_checkpoint,
+        current_justified_checkpoint=pre.current_justified_checkpoint,
+        finalized_checkpoint=pre.finalized_checkpoint,
+        # Inactivity
+        inactivity_scores=pre.inactivity_scores,
+        # Sync
+        current_sync_committee=pre.current_sync_committee,
+        next_sync_committee=pre.next_sync_committee,
+        # Execution-layer
+        latest_execution_payload_header=latest_execution_payload_header,
+        # Withdrawals
+        next_withdrawal_index=pre.next_withdrawal_index,
+        next_withdrawal_validator_index=pre.next_withdrawal_validator_index,
+        # Deep history valid from Capella onwards
+        # FIXME most likely wrong
+        historical_summaries=List[HistoricalSummary, HISTORICAL_ROOTS_LIMIT]([]),
+    )
+
+    return post
+```