175 lines
10 KiB
Markdown
175 lines
10 KiB
Markdown
# Ethereum 2.0 Sharding -- Network specification
|
|
|
|
**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)
|
|
- [Constants](#constants)
|
|
- [Misc](#misc)
|
|
- [Gossip domain](#gossip-domain)
|
|
- [Topics and messages](#topics-and-messages)
|
|
- [Shard blob subnets](#shard-blob-subnets)
|
|
- [`shard_blob_{subnet_id}`](#shard_blob_subnet_id)
|
|
- [Global topics](#global-topics)
|
|
- [`shard_blob_header`](#shard_blob_header)
|
|
- [`shard_blob_tx`](#shard_blob_tx)
|
|
- [`shard_proposer_slashing`](#shard_proposer_slashing)
|
|
|
|
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
|
|
<!-- /TOC -->
|
|
|
|
|
|
## Introduction
|
|
|
|
The specification of these changes continues in the same format as the network specifications of previous upgrades, and assumes them as pre-requisite.
|
|
The adjustments and additions for Shards are outlined in this document.
|
|
|
|
## Constants
|
|
|
|
### Misc
|
|
|
|
| Name | Value | Description |
|
|
| ---- | ----- | ----------- |
|
|
| `SHARD_BLOB_SUBNET_COUNT` | `64` | The number of `shard_blob_{subnet_id}` subnets used in the gossipsub protocol. |
|
|
|
|
## Gossip domain
|
|
|
|
### Topics and messages
|
|
|
|
Following the same scheme as the [Phase0 gossip topics](../phase0/p2p-interface.md#topics-and-messages), names and payload types are:
|
|
|
|
| Name | Message Type |
|
|
|---------------------------------|--------------------------|
|
|
| `shard_blob_{subnet_id}` | `SignedShardBlob` |
|
|
| `shard_blob_header` | `SignedShardBlobHeader` |
|
|
| `shard_blob_tx` | `SignedShardBlobHeader` |
|
|
| `shard_proposer_slashing` | `ShardProposerSlashing` |
|
|
|
|
The [DAS network specification](./das-p2p.md) defines additional topics.
|
|
|
|
#### Shard blob subnets
|
|
|
|
Shard blob subnets are used by builders to make their blobs available after selection by shard proposers.
|
|
|
|
##### `shard_blob_{subnet_id}`
|
|
|
|
Shard blob data, in the form of a `SignedShardBlob` is published to the `shard_blob_{subnet_id}` subnets.
|
|
|
|
```python
|
|
def compute_subnet_for_shard_blob(state: BeaconState, slot: Slot, shard: Shard) -> uint64:
|
|
"""
|
|
Compute the correct subnet for a shard blob publication.
|
|
Note, this mimics compute_subnet_for_attestation().
|
|
"""
|
|
committee_index = compute_committee_index_from_shard(state, slot, shard)
|
|
committees_per_slot = get_committee_count_per_slot(state, compute_epoch_at_slot(slot))
|
|
slots_since_epoch_start = Slot(slot % SLOTS_PER_EPOCH)
|
|
committees_since_epoch_start = committees_per_slot * slots_since_epoch_start
|
|
|
|
return uint64((committees_since_epoch_start + committee_index) % SHARD_BLOB_SUBNET_COUNT)
|
|
```
|
|
|
|
The following validations MUST pass before forwarding the `signed_blob`,
|
|
on the horizontal subnet or creating samples for it. Alias `blob = signed_blob.message`.
|
|
|
|
- _[IGNORE]_ The `blob` is not from a future slot (with a `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance) --
|
|
i.e. validate that `blob.slot <= current_slot`
|
|
(a client MAY queue future blobs for processing at the appropriate slot).
|
|
- _[IGNORE]_ The `blob` is new enough to still be processed --
|
|
i.e. validate that `compute_epoch_at_slot(blob.slot) >= get_previous_epoch(state)`
|
|
- _[REJECT]_ The shard blob is for an active shard --
|
|
i.e. `blob.shard < get_active_shard_count(state, compute_epoch_at_slot(blob.slot))`
|
|
- _[REJECT]_ The `blob.shard` MUST have a committee at the `blob.slot` --
|
|
i.e. validate that `compute_committee_index_from_shard(state, blob.slot, blob.shard)` doesn't raise an error
|
|
- _[REJECT]_ The shard blob is for the correct subnet --
|
|
i.e. `compute_subnet_for_shard_blob(state, blob.slot, blob.shard) == subnet_id`
|
|
- _[IGNORE]_ The blob is the first blob with valid signature received for the `(blob.proposer_index, blob.slot, blob.shard)` combination.
|
|
- _[REJECT]_ The blob is not too large -- the data MUST NOT be larger than the SSZ list-limit, and a client MAY apply stricter bounds.
|
|
- _[REJECT]_ The `blob.body.data` MUST NOT contain any point `p >= MODULUS`. Although it is a `uint256`, not the full 256 bit range is valid.
|
|
- _[REJECT]_ The blob builder defined by `blob.builder_index` exists and has sufficient balance to back the fee payment.
|
|
- _[REJECT]_ The blob signature, `signed_blob.signature`, is valid for the aggregate of proposer and builder --
|
|
i.e. `bls.FastAggregateVerify([builder_pubkey, proposer_pubkey], blob_signing_root, signed_blob.signature)`.
|
|
- _[REJECT]_ The blob is proposed by the expected `proposer_index` for the blob's `slot` and `shard`,
|
|
in the context of the current shuffling (defined by `blob.body.beacon_block_root`/`slot`).
|
|
If the `proposer_index` cannot immediately be verified against the expected shuffling,
|
|
the blob MAY be queued for later processing while proposers for the blob's branch are calculated --
|
|
in such a case _do not_ `REJECT`, instead `IGNORE` this message.
|
|
|
|
#### Global topics
|
|
|
|
There are three additional global topics for Sharding.
|
|
|
|
- `shard_blob_header`: co-signed headers to be included on-chain and to serve as a signal to the builder to publish full data.
|
|
- `shard_blob_tx`: builder-signed headers, also known as "data transaction".
|
|
- `shard_proposer_slashing`: slashings of duplicate shard proposals.
|
|
|
|
##### `shard_blob_header`
|
|
|
|
Shard header data, in the form of a `SignedShardBlobHeader` is published to the global `shard_blob_header` subnet.
|
|
Shard blob headers select shard blob bids by builders
|
|
and should be timely to ensure builders can publish the full shard blob before subsequent attestations.
|
|
|
|
The following validations MUST pass before forwarding the `signed_blob_header` on the network. Alias `header = signed_blob_header.message`.
|
|
|
|
- _[IGNORE]_ The `header` is not from a future slot (with a `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance) --
|
|
i.e. validate that `header.slot <= current_slot`
|
|
(a client MAY queue future headers for processing at the appropriate slot).
|
|
- _[IGNORE]_ The header is new enough to still be processed --
|
|
i.e. validate that `compute_epoch_at_slot(header.slot) >= get_previous_epoch(state)`
|
|
- _[REJECT]_ The shard header is for an active shard --
|
|
i.e. `header.shard < get_active_shard_count(state, compute_epoch_at_slot(header.slot))`
|
|
- _[REJECT]_ The `header.shard` MUST have a committee at the `header.slot` --
|
|
i.e. validate that `compute_committee_index_from_shard(state, header.slot, header.shard)` doesn't raise an error
|
|
- _[IGNORE]_ The header is the first header with valid signature received for the `(header.proposer_index, header.slot, header.shard)` combination.
|
|
- _[REJECT]_ The blob builder defined by `blob.builder_index` exists and has sufficient balance to back the fee payment.
|
|
- _[REJECT]_ The header signature, `signed_blob_header.signature`, is valid for the aggregate of proposer and builder --
|
|
i.e. `bls.FastAggregateVerify([builder_pubkey, proposer_pubkey], blob_signing_root, signed_blob_header.signature)`.
|
|
- _[REJECT]_ The header is proposed by the expected `proposer_index` for the blob's `header.slot` and `header.shard`
|
|
in the context of the current shuffling (defined by `header.body_summary.beacon_block_root`/`slot`).
|
|
If the `proposer_index` cannot immediately be verified against the expected shuffling,
|
|
the blob MAY be queued for later processing while proposers for the blob's branch are calculated --
|
|
in such a case _do not_ `REJECT`, instead `IGNORE` this message.
|
|
|
|
##### `shard_blob_tx`
|
|
|
|
Shard data-transactions in the form of a `SignedShardBlobHeader` are published to the global `shard_blob_tx` subnet.
|
|
These shard blob headers are signed solely by the blob-builder.
|
|
|
|
The following validations MUST pass before forwarding the `signed_blob_header` on the network. Alias `header = signed_blob_header.message`.
|
|
|
|
- _[IGNORE]_ The header is not from a future slot (with a `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance) --
|
|
i.e. validate that `header.slot <= current_slot`
|
|
(a client MAY queue future headers for processing at the appropriate slot).
|
|
- _[IGNORE]_ The header is new enough to still be processed --
|
|
i.e. validate that `compute_epoch_at_slot(header.slot) >= get_previous_epoch(state)`
|
|
- _[REJECT]_ The shard header is for an active shard --
|
|
i.e. `header.shard < get_active_shard_count(state, compute_epoch_at_slot(header.slot))`
|
|
- _[REJECT]_ The `header.shard` MUST have a committee at the `header.slot` --
|
|
i.e. validate that `compute_committee_index_from_shard(state, header.slot, header.shard)` doesn't raise an error
|
|
- _[IGNORE]_ The header is the first header with valid signature received for the `(header.builder_index, header.slot, header.shard)` combination.
|
|
- _[REJECT]_ The blob builder, define by `header.builder_index`, exists and has sufficient balance to back the fee payment.
|
|
- _[IGNORE]_ The header fee SHOULD be higher than previously seen headers for `(header.slot, header.shard)`, from any builder.
|
|
Propagating nodes MAY increase fee increments in case of spam.
|
|
- _[REJECT]_ The header signature, `signed_blob_header.signature`, is valid for ONLY the builder --
|
|
i.e. `bls.Verify(builder_pubkey, blob_signing_root, signed_blob_header.signature)`. The signature is not an aggregate with the proposer.
|
|
- _[REJECT]_ The header is designated for proposal by the expected `proposer_index` for the blob's `header.slot` and `header.shard`
|
|
in the context of the current shuffling (defined by `header.body_summary.beacon_block_root`/`slot`).
|
|
If the `proposer_index` cannot immediately be verified against the expected shuffling,
|
|
the blob MAY be queued for later processing while proposers for the blob's branch are calculated --
|
|
in such a case _do not_ `REJECT`, instead `IGNORE` this message.
|
|
|
|
##### `shard_proposer_slashing`
|
|
|
|
Shard proposer slashings, in the form of `ShardProposerSlashing`, are published to the global `shard_proposer_slashing` topic.
|
|
|
|
The following validations MUST pass before forwarding the `shard_proposer_slashing` on to the network.
|
|
- _[IGNORE]_ The shard proposer slashing is the first valid shard proposer slashing received
|
|
for the proposer with index `proposer_slashing.proposer_index`.
|
|
The `proposer_slashing.slot` and `proposer_slashing.shard` are ignored, there are no repeated or per-shard slashings.
|
|
- _[REJECT]_ All of the conditions within `process_shard_proposer_slashing` pass validation.
|