From 7ffc9c5bc0147203b765ee370c76e13a96fb9ce3 Mon Sep 17 00:00:00 2001 From: Justin Date: Tue, 17 Nov 2020 14:18:58 +0000 Subject: [PATCH] More polish and fixes to the sync protocol --- specs/lightclient/sync-protocol.md | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) diff --git a/specs/lightclient/sync-protocol.md b/specs/lightclient/sync-protocol.md index 8fb94bfa5..6977d5862 100644 --- a/specs/lightclient/sync-protocol.md +++ b/specs/lightclient/sync-protocol.md @@ -36,7 +36,6 @@ This document suggests a minimal light client design for the beacon chain that u | Name | Value | | - | - | | `NEXT_SYNC_COMMITTEE_INDEX` | `IndexConcat(Index(BeaconBlock, 'state_root'), Index(BeaconState, 'next_sync_committee'))` | -| `FORK_INDEX` | `IndexConcat(Index(BeaconBlock, 'state_root'), Index(BeaconState, 'fork'))` | ## Configuration @@ -60,8 +59,6 @@ This document suggests a minimal light client design for the beacon chain that u class LightClientSnapshot(Container): # Beacon block header header: BeaconBlockHeader - # Fork data corresponding to the header - fork: Fork # Sync committees corresponding to the header current_sync_committee: SyncCommittee next_sync_committee: SyncCommittee @@ -73,12 +70,13 @@ class LightClientSnapshot(Container): class LightClientUpdate(Container): # Updated snapshot snapshot: LightClientSnapshot - # Merkle branches for the updated snapshot - fork_branch: Vector[Bytes32, log_2(FORK_INDEX)] - next_sync_committee_branch: Vector[Bytes32, log_2(NEXT_SYNC_COMMITTEE_INDEX)] + # Merkle branches for the next sync committee + next_sync_committee_branch: Vector[Bytes32, log2(NEXT_SYNC_COMMITTEE_INDEX)] # Sync committee aggregate signature sync_committee_bits: Bitlist[MAX_SYNC_COMMITTEE_SIZE] sync_committee_signature: BLSSignature + # Fork version corresponding to the aggregate signature + fork_version ``` #### `LightClientStore` @@ -121,22 +119,13 @@ def is_valid_light_client_update(store: LightClientStore, update: LightClientUpd root=hash_tree_root(new_snapshot.header), ) - # Verify new snapshot fork - assert is_valid_merkle_branch( - leaf=hash_tree_root(new_snapshot.fork), - branch=update.fork_branch, - depth=log2(FORK_INDEX), - index=FORK_INDEX % 2**log2(FORK_INDEX), - root=hash_tree_root(new_snapshot.header), - ) - # Verify sync committee bitfield length sync_committee = new_snapshot.current_sync_committee assert len(update.sync_committee_bits) == len(sync_committee) # Verify sync committee aggregate signature participant_pubkeys = [pubkey for (bit, pubkey) in zip(update.sync_committee_bits, sync_committee.pubkeys) if bit] - domain = compute_domain(DOMAIN_SYNC_COMMITTEE, fork_version.current_version) + domain = compute_domain(DOMAIN_SYNC_COMMITTEE, update.fork_version) signing_root = compute_signing_root(new_snapshot.header, domain) assert bls.FastAggregateVerify(participant_pubkeys, signing_root, update.sync_committee_signature)