Full BLS Validatition for lightclient update (#5751)

cmd/lightclient/lightclient/verify.go

@@ -7,7 +7,7 @@ import (
 	"github.com/ledgerwatch/erigon/cmd/lightclient/fork"
 	"github.com/ledgerwatch/erigon/cmd/lightclient/utils"
 	"github.com/ledgerwatch/erigon/common"
-	//"github.com/prysmaticlabs/go-bls"
+	blst "github.com/supranational/blst/bindings/go"
 )
 
 const (
@@ -15,7 +15,10 @@ const (
 	FinalizedRootIndex           = 105
 )
 
-var DomainSyncCommittee = common.Hex2Bytes("07000000")
+var (
+	DomainSyncCommittee = common.Hex2Bytes("07000000")
+	dst                 = []byte("BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_")
+)
 
 func (l *LightClient) validateLegacyUpdate(update *cltypes.LightClientUpdate, finalityUpdate bool) (bool, error) {
 	if update.SyncAggregate.Sum() < MinSyncCommitteeParticipants {
@@ -112,24 +115,23 @@ func (l *LightClient) validateLegacyUpdate(update *cltypes.LightClientUpdate, fi
 	if err != nil {
 		return false, err
 	}
-	// Create signature objects
-	/*var signature bls.Sign
-	if err := signature.Deserialize(update.SyncAggregate.SyncCommiteeSignature[:]); err != nil {
+	_ = signingRoot
+	signature, err := utils.SignatureFromBytes(update.SyncAggregate.SyncCommiteeSignature[:])
+	if err != nil {
 		return false, err
 	}
-	// Aggreggate public keys
-	var pubKey bls.PublicKey
+
+	pks := []*blst.P1Affine{}
+
 	for _, key := range pubkeys {
-		var currPubKey bls.PublicKey
-		if err := currPubKey.Deserialize(key[:]); err != nil {
+		pk, err := utils.PublicKeyFromBytes(key[:])
+		if err != nil {
 			return false, err
 		}
-		pubKey.Add(&currPubKey)
-	}*/
-	_ = signingRoot
-	_ = pubkeys
-	return true, nil
-	// return signature.Verify(&pubKey, signingRoot[:]), nil
+		pks = append(pks, pk)
+	}
+
+	return signature.FastAggregateVerify(true, pks, signingRoot[:], dst), nil
 }
 
 func (l *LightClient) validateOptimisticUpdate(update *cltypes.LightClientOptimisticUpdate) (bool, error) {
@@ -139,78 +141,3 @@ func (l *LightClient) validateOptimisticUpdate(update *cltypes.LightClientOptimi
 func (l *LightClient) validateFinalityUpdate(update *cltypes.LightClientFinalityUpdate) (bool, error) {
 	return true, nil
 }
-
-/*def validate_light_client_update(store: LightClientStore,
-                               update: LightClientUpdate,
-                               current_slot: Slot,
-                               genesis_validators_root: Root) -> None:
-  # Verify sync committee has sufficient participants
-  sync_aggregate = update.sync_aggregate
-  assert sum(sync_aggregate.sync_committee_bits) >= MIN_SYNC_COMMITTEE_PARTICIPANTS
-
-  # Verify update does not skip a sync committee period
-  assert current_slot >= update.signature_slot > update.attested_header.slot >= update.finalized_header.slot
-  store_period = compute_sync_committee_period_at_slot(store.finalized_header.slot)
-  update_signature_period = compute_sync_committee_period_at_slot(update.signature_slot)
-  if is_next_sync_committee_known(store):
-      assert update_signature_period in (store_period, store_period + 1)
-  else:
-      assert update_signature_period == store_period
-
-  # Verify update is relevant
-  update_attested_period = compute_sync_committee_period_at_slot(update.attested_header.slot)
-  update_has_next_sync_committee = not is_next_sync_committee_known(store) and (
-      is_sync_committee_update(update) and update_attested_period == store_period
-  )
-  assert (
-      update.attested_header.slot > store.finalized_header.slot
-      or update_has_next_sync_committee
-  )
-
-  # Verify that the `finality_branch`, if present, confirms `finalized_header`
-  # to match the finalized checkpoint root saved in the state of `attested_header`.
-  # Note that the genesis finalized checkpoint root is represented as a zero hash.
-  if not is_finality_update(update):
-      assert update.finalized_header == BeaconBlockHeader()
-  else:
-      if update.finalized_header.slot == GENESIS_SLOT:
-          assert update.finalized_header == BeaconBlockHeader()
-          finalized_root = Bytes32()
-      else:
-          finalized_root = hash_tree_root(update.finalized_header)
-      assert is_valid_merkle_branch(
-          leaf=finalized_root,
-          branch=update.finality_branch,
-          depth=floorlog2(FINALIZED_ROOT_INDEX),
-          index=get_subtree_index(FINALIZED_ROOT_INDEX),
-          root=update.attested_header.state_root,
-      )
-
-  # Verify that the `next_sync_committee`, if present, actually is the next sync committee saved in the
-  # state of the `attested_header`
-  if not is_sync_committee_update(update):
-      assert update.next_sync_committee == SyncCommittee()
-  else:
-      if update_attested_period == store_period and is_next_sync_committee_known(store):
-          assert update.next_sync_committee == store.next_sync_committee
-      assert is_valid_merkle_branch(
-          leaf=hash_tree_root(update.next_sync_committee),
-          branch=update.next_sync_committee_branch,
-          depth=floorlog2(NEXT_SYNC_COMMITTEE_INDEX),
-          index=get_subtree_index(NEXT_SYNC_COMMITTEE_INDEX),
-          root=update.attested_header.state_root,
-      )
-
-  # Verify sync committee aggregate signature
-  if update_signature_period == store_period:
-      sync_committee = store.current_sync_committee
-  else:
-      sync_committee = store.next_sync_committee
-  participant_pubkeys = [
-      pubkey for (bit, pubkey) in zip(sync_aggregate.sync_committee_bits, sync_committee.pubkeys)
-      if bit
-  ]
-  fork_version = compute_fork_version(compute_epoch_at_slot(update.signature_slot))
-  domain = compute_domain(DOMAIN_SYNC_COMMITTEE, fork_version, genesis_validators_root)
-  signing_root = compute_signing_root(update.attested_header, domain)
-  assert bls.FastAggregateVerify(participant_pubkeys, signing_root, sync_aggregate.sync_committee_signature)*/

cmd/lightclient/main.go

@@ -32,6 +32,7 @@ var (
 const DefaultUri = "https://beaconstate.ethstaker.cc/eth/v2/debug/beacon/states/finalized"
 
 func main() {
+
 	ctx := context.Background()
 	log.Root().SetHandler(log.LvlFilterHandler(log.LvlInfo, log.StderrHandler))
 	addr := "localhost:7777"

cmd/lightclient/sentinel/communication/ssz_snappy/stream.go

@@ -199,7 +199,6 @@ func readUvarint(r io.Reader) (x uint64, err error) {
 func DecodeLightClientUpdate(data []byte) (*cltypes.LightClientUpdate, error) {
 	resp := &cltypes.LightClientUpdate{}
 	singleLen := resp.SizeSSZ()
-	fmt.Println(len(data[7:]))
 	r := bytes.NewReader(data[7:])
 
 	sr := snappy.NewReader(r)

cmd/lightclient/utils/crypto.go

@@ -15,8 +15,12 @@ package utils
 
 import (
 	"crypto/sha256"
+	"errors"
+	"fmt"
 	"hash"
 	"sync"
+
+	blst "github.com/supranational/blst/bindings/go"
 )
 
 var hasherPool = sync.Pool{
@@ -40,3 +44,39 @@ func Keccak256(data []byte) [32]byte {
 
 	return b
 }
+
+// PublicKeyFromBytes creates a BLS public key from a  BigEndian byte slice.
+func PublicKeyFromBytes(pubKey []byte) (*blst.P1Affine, error) {
+	if len(pubKey) != 48 {
+		return nil, fmt.Errorf("public key must be 48 bytes")
+	}
+
+	// Subgroup check NOT done when decompressing pubkey.
+	p := new(blst.P1Affine).Uncompress(pubKey)
+	if p == nil {
+		return nil, errors.New("could not unmarshal bytes into public key")
+	}
+	// Subgroup and infinity check
+	if !p.KeyValidate() {
+		return nil, fmt.Errorf("infinite key")
+	}
+
+	return p, nil
+}
+
+// SignatureFromBytes creates a BLS signature from a LittleEndian byte slice.
+func SignatureFromBytes(sig []byte) (*blst.P2Affine, error) {
+	if len(sig) != 96 {
+		return nil, fmt.Errorf("signature must be 96 bytes")
+	}
+	signature := new(blst.P2Affine).Uncompress(sig)
+	if signature == nil {
+		return nil, errors.New("could not unmarshal bytes into signature")
+	}
+	// Group check signature. Do not check for infinity since an aggregated signature
+	// could be infinite.
+	if !signature.SigValidate(false) {
+		return nil, errors.New("signature not in group")
+	}
+	return signature, nil
+}

go.mod

@@ -63,6 +63,7 @@ require (
 	github.com/spf13/cobra v1.5.0
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.8.0
+	github.com/supranational/blst v0.3.10
 	github.com/tendermint/go-amino v0.14.1
 	github.com/tendermint/tendermint v0.31.12
 	github.com/torquem-ch/mdbx-go v0.26.1

go.sum

@@ -939,6 +939,8 @@ github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/supranational/blst v0.3.10 h1:CMciDZ/h4pXDDXQASe8ZGTNKUiVNxVVA5hpci2Uuhuk=
+github.com/supranational/blst v0.3.10/go.mod h1:jZJtfjgudtNl4en1tzwPIV3KjUnQUvG3/j+w+fVonLw=
 github.com/tarm/serial v0.0.0-20180830185346-98f6abe2eb07/go.mod h1:kDXzergiv9cbyO7IOYJZWg1U88JhDg3PB6klq9Hg2pA=
 github.com/tendermint/go-amino v0.14.1 h1:o2WudxNfdLNBwMyl2dqOJxiro5rfrEaU0Ugs6offJMk=
 github.com/tendermint/go-amino v0.14.1/go.mod h1:i/UKE5Uocn+argJJBb12qTZsCDBcAYMbR92AaJVmKso=