EIP-4844: consensus-layer specs of Shard Blob Transactions

Makefile

@@ -27,7 +27,8 @@ MARKDOWN_FILES = $(wildcard $(SPEC_DIR)/phase0/*.md) $(wildcard $(SPEC_DIR)/alta
                  $(wildcard $(SPEC_DIR)/bellatrix/*.md) \
                  $(wildcard $(SPEC_DIR)/custody/*.md) \
                  $(wildcard $(SPEC_DIR)/das/*.md) \
-                 $(wildcard $(SPEC_DIR)/sharding/*.md)
+                 $(wildcard $(SPEC_DIR)/sharding/*.md) \
+                 $(wildcard $(SPEC_DIR)/eip4844/*.md)
 
 COV_HTML_OUT=.htmlcov
 COV_HTML_OUT_DIR=$(PY_SPEC_DIR)/$(COV_HTML_OUT)

specs/bellatrix/p2p-interface.md

@@ -110,7 +110,7 @@ The following gossip validation from prior specifications MUST NOT be applied if
 ### Transitioning the gossip
 
 See gossip transition details found in the [Altair document](../altair/p2p-interface.md#transitioning-the-gossip) for
-details on how to handle transitioning gossip topics for Bellatrix.
+details on how to handle transitioning gossip topics for EIP-4844.
 
 ## The Req/Resp domain
 

specs/eip4844/beacon-chain.md

@@ -0,0 +1,190 @@
+# EIP-4844 -- The Beacon Chain
+
+**Notice**: This document is a work-in-progress for researchers and implementers.
+
+## 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)
+- [Constants](#constants)
+  - [Domain types](#domain-types)
+- [Preset](#preset)
+  - [Trusted setup](#trusted-setup)
+- [Configuration](#configuration)
+- [Containers](#containers)
+  - [Extended containers](#extended-containers)
+    - [`BeaconBlockBody`](#beaconblockbody)
+- [Helper functions](#helper-functions)
+  - [KZG core](#kzg-core)
+    - [`blob_to_kzg`](#blob_to_kzg)
+    - [`kzg_to_versioned_hash`](#kzg_to_versioned_hash)
+  - [Misc](#misc)
+    - [`tx_peek_blob_versioned_hashes`](#tx_peek_blob_versioned_hashes)
+    - [`verify_kzgs_against_transactions`](#verify_kzgs_against_transactions)
+- [Beacon chain state transition function](#beacon-chain-state-transition-function)
+  - [Block processing](#block-processing)
+    - [Blob KZGs](#blob-kzgs)
+- [Testing](#testing)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+<!-- /TOC -->
+
+## Introduction
+
+This upgrade adds blobs to the beacon chain as part of EIP-4844.
+
+## Custom types
+
+| Name | SSZ equivalent | Description |
+| - | - | - |
+| `BLSFieldElement` | `uint256` | `x < BLS_MODULUS` |
+| `Blob` | `Vector[BLSFieldElement, FIELD_ELEMENTS_PER_BLOB]` | |
+| `VersionedHash` | `Bytes32` | |
+| `KZGCommitment` | `Bytes48` | Same as BLS standard "is valid pubkey" check but also allows `0x00..00` for point-at-infinity |
+
+## Constants
+
+| Name | Value |
+| - | - |
+| `BLOB_TX_TYPE` | `uint8(0x05)` |
+| `FIELD_ELEMENTS_PER_BLOB` | `4096` |
+| `BLS_MODULUS` | `52435875175126190479447740508185965837690552500527637822603658699938581184513` |
+
+### Domain types
+
+| Name | Value |
+| - | - |
+| `DOMAIN_BLOBS_SIDECAR` | `DomainType('0x0a000000')` |
+
+## Preset
+
+### Trusted setup
+
+The trusted setup is part of the preset: during testing a `minimal` insecure variant may be used,
+but reusing the `mainnet` settings in public networks is a critical security requirement.
+
+| Name | Value |
+| - | - |
+| `KZG_SETUP_G2` | `Vector[G2Point, FIELD_ELEMENTS_PER_BLOB]`, contents TBD |
+| `KZG_SETUP_LAGRANGE` | `Vector[BLSCommitment, FIELD_ELEMENTS_PER_BLOB]`, contents TBD |
+
+## Configuration
+
+
+## Containers
+
+### Extended containers
+
+#### `BeaconBlockBody`
+
+Note: `BeaconBlock` and `SignedBeaconBlock` types are updated indirectly.
+
+```python
+class BeaconBlockBody(Container):
+    randao_reveal: BLSSignature
+    eth1_data: Eth1Data  # Eth1 data vote
+    graffiti: Bytes32  # Arbitrary data
+    # Operations
+    proposer_slashings: List[ProposerSlashing, MAX_PROPOSER_SLASHINGS]
+    attester_slashings: List[AttesterSlashing, MAX_ATTESTER_SLASHINGS]
+    attestations: List[Attestation, MAX_ATTESTATIONS]
+    deposits: List[Deposit, MAX_DEPOSITS]
+    voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS]
+    sync_aggregate: SyncAggregate
+    # Execution
+    execution_payload: ExecutionPayload 
+    blob_kzgs: List[KZGCommitment, MAX_BLOBS_PER_BLOCK]  # [New in EIP-4844]
+```
+
+## Helper functions
+
+### KZG core
+
+KZG core functions. These are also defined in EIP-4844 execution specs.
+
+#### `blob_to_kzg`
+
+```python
+def blob_to_kzg(blob: Blob) -> KZGCommitment:
+    computed_kzg = bls.Z1
+    for value, point_kzg in zip(blob, KZG_SETUP_LAGRANGE):
+        assert value < BLS_MODULUS
+        computed_kzg = bls.add(
+            computed_kzg,
+            bls.multiply(point_kzg, value)
+        )
+    return computed_kzg
+```
+
+#### `kzg_to_versioned_hash`
+
+```python
+def kzg_to_versioned_hash(kzg: KZGCommitment) -> VersionedHash:
+    return BLOB_COMMITMENT_VERSION_KZG + hash(kzg)[1:]
+```
+
+### Misc
+
+#### `tx_peek_blob_versioned_hashes`
+
+This function retrieves the hashes from the `SignedBlobTransaction` as defined in EIP-4844, using SSZ offsets.
+Offsets are little-endian `uint32` values, as defined in the [SSZ specification](../../ssz/simple-serialize.md).
+
+```python
+def tx_peek_blob_versioned_hashes(opaque_tx: Transaction) -> Sequence[VersionedHash]:
+    assert opaque_tx[0] == BLOB_TX_TYPE
+    message_offset = 1 + uint32.decode_bytes(opaque_tx[1:5])
+    # field offset: 32 + 8 + 32 + 32 + 8 + 4 + 32 + 4 + 4 = 156
+    blob_versioned_hashes_offset = uint32.decode_bytes(opaque_tx[message_offset+156:message_offset+160])
+    return [VersionedHash(opaque_tx[x:x+32]) for x in range(blob_versioned_hashes_offset, len(opaque_tx), 32)]
+```
+
+#### `verify_kzgs_against_transactions`
+
+```python
+def verify_kzgs_against_transactions(transactions: Sequence[Transaction], blob_kzgs: Sequence[KZGCommitment]) -> bool:
+   all_versioned_hashes = []
+   for tx in transactions:
+      if opaque_tx[0] == BLOB_TX_TYPE:
+         all_versioned_hashes.extend(tx_peek_blob_versioned_hashes(tx))
+   return all_versioned_hashes == [ksg_to_version_hash(kzg) for kzg in blob_kzgs]
+```
+
+## Beacon chain state transition function
+
+### Block processing
+
+```python
+def process_block(state: BeaconState, block: BeaconBlock) -> None:
+    process_block_header(state, block)
+    if is_execution_enabled(state, block.body):
+        process_execution_payload(state, block.body.execution_payload, EXECUTION_ENGINE)
+    process_randao(state, block.body)
+    process_eth1_data(state, block.body)
+    process_operations(state, block.body)
+    process_sync_aggregate(state, block.body.sync_aggregate)
+    process_blob_kzgs(state, block.body)  # [New in EIP-4844]
+```
+
+#### Blob KZGs
+
+```python
+def process_blob_kzgs(state: BeaconState, body: BeaconBlockBody):
+    assert verify_kzgs_against_transactions(body.execution_payload.transactions, body.blob_kzgs)
+```
+
+## Testing
+
+*Note*: The function `initialize_beacon_state_from_eth1` is modified for pure EIP-4844 testing only.
+
+The `BeaconState` initialization is unchanged, except for the use of the updated `eip4844.BeaconBlockBody` type 
+when initializing the first body-root:
+
+```python
+state.latest_block_header=BeaconBlockHeader(body_root=hash_tree_root(BeaconBlockBody())),
+```
+

specs/eip4844/fork.md

@@ -0,0 +1,43 @@
+# EIP-4844 -- Fork Logic
+
+**Notice**: This document is a work-in-progress for researchers and implementers.
+
+## 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)
+- [Fork to EIP-4844](#fork-to-eip-4844)
+  - [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 EIP-4844 upgrade.
+
+## Configuration
+
+Warning: this configuration is not definitive.
+
+| Name | Value |
+| - | - |
+| `EIP4844_FORK_VERSION` | `Version('0x03000000')` |
+| `EIP4844_FORK_EPOCH` | `Epoch(18446744073709551615)` **TBD** |
+
+## Fork to EIP-4844
+
+### Fork trigger
+
+TBD. This fork is defined for testing purposes, the EIP may be combined with other consensus-layer upgrade.
+For now we assume the condition will be triggered at epoch `EIP4844_FORK_EPOCH`.
+
+Note that for the pure EIP-4844 networks, we don't apply `upgrade_to_eip4844` since it starts with EIP-4844 version logic.
+
+### Upgrading the state
+
+The `eip4844.BeaconState` format is equal to the `bellatrix.BeaconState` format, no upgrade has to be performed.
+