adding support for validating multibls for same shard (#2402)

adding unit test

fixing golint issue

fixing minor issue

cmd/harmony/main.go

@@ -250,6 +250,9 @@ func setupStakingNodeAccount() error {
 	if err != nil {
 		return errors.Wrap(err, "cannot determine shard to join")
 	}
+	if err := nodeconfig.GetDefaultConfig().ValidateConsensusKeysForSameShard(pubKey.PublicKey, shardID); err != nil {
+		return err
+	}
 	for _, blsKey := range pubKey.PublicKey {
 		initialAccount := &genesis.DeployAccount{}
 		initialAccount.ShardID = shardID

internal/configs/node/config.go

@@ -8,6 +8,7 @@ import (
 	"math/big"
 	"sync"
 
+	"github.com/harmony-one/bls/ffi/go/bls"
 	shardingconfig "github.com/harmony-one/harmony/internal/configs/sharding"
 	"github.com/harmony-one/harmony/internal/params"
 	"github.com/harmony-one/harmony/multibls"
@@ -292,6 +293,25 @@ func (conf *ConfigType) ShardIDFromConsensusKey() (uint32, error) {
 	return uint32(shardID.Uint64()), nil
 }
 
+// ValidateConsensusKeysForSameShard checks if all consensus public keys belong to the same shard
+func (conf *ConfigType) ValidateConsensusKeysForSameShard(pubkeys []*bls.PublicKey, sID uint32) error {
+	var pubKey shard.BlsPublicKey
+	for _, key := range pubkeys {
+		if err := pubKey.FromLibBLSPublicKey(key); err != nil {
+			return errors.Wrapf(err,
+				"cannot convert libbls public key %s to internal form",
+				key.SerializeToHexStr())
+		}
+		epoch := conf.networkType.ChainConfig().StakingEpoch
+		numShards := conf.shardingSchedule.InstanceForEpoch(epoch).NumShards()
+		shardID := new(big.Int).Mod(pubKey.Big(), big.NewInt(int64(numShards)))
+		if uint32(shardID.Uint64()) != sID {
+			return errors.New("bls keys do not belong to the same shard")
+		}
+	}
+	return nil
+}
+
 // ChainConfig returns the chain configuration for the network type.
 func (t NetworkType) ChainConfig() params.ChainConfig {
 	switch t {

internal/configs/node/config_test.go

@@ -6,7 +6,10 @@ import (
 
 	"github.com/golang/mock/gomock"
 	"github.com/harmony-one/bls/ffi/go/bls"
+	"github.com/pkg/errors"
 
+	"github.com/harmony-one/harmony/internal/blsgen"
+	shardingconfig "github.com/harmony-one/harmony/internal/configs/sharding"
 	mock_shardingconfig "github.com/harmony-one/harmony/internal/configs/sharding/mock"
 	"github.com/harmony-one/harmony/internal/params"
 	"github.com/harmony-one/harmony/multibls"
@@ -131,3 +134,44 @@ func TestConfigType_ShardIDFromConsensusKey(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateConsensusKeysForSameShard(t *testing.T) {
+	// set localnet config
+	networkType := "localnet"
+	schedule := shardingconfig.LocalnetSchedule
+	netType := NetworkType(networkType)
+	SetNetworkType(netType)
+	SetShardingSchedule(schedule)
+
+	// import two keys that belong to same shard and test ValidateConsensusKeysForSameShard
+	keyPath1 := "../../../.hmy/65f55eb3052f9e9f632b2923be594ba77c55543f5c58ee1454b9cfd658d25e06373b0f7d42a19c84768139ea294f6204.key"
+	priKey1, err := blsgen.LoadBlsKeyWithPassPhrase(keyPath1, "")
+	pubKey1 := priKey1.GetPublicKey()
+	if err != nil {
+		t.Error(err)
+	}
+	keyPath2 := "../../../.hmy/ca86e551ee42adaaa6477322d7db869d3e203c00d7b86c82ebee629ad79cb6d57b8f3db28336778ec2180e56a8e07296.key"
+	priKey2, err := blsgen.LoadBlsKeyWithPassPhrase(keyPath2, "")
+	pubKey2 := priKey2.GetPublicKey()
+	if err != nil {
+		t.Error(err)
+	}
+	keys := []*bls.PublicKey{}
+	keys = append(keys, pubKey1)
+	keys = append(keys, pubKey2)
+	if err := GetDefaultConfig().ValidateConsensusKeysForSameShard(keys, 0); err != nil {
+		t.Error("expected", nil, "got", err)
+	}
+	// add third key in different shard and test ValidateConsensusKeysForSameShard
+	keyPath3 := "../../../.hmy/68ae289d73332872ec8d04ac256ca0f5453c88ad392730c5741b6055bc3ec3d086ab03637713a29f459177aaa8340615.key"
+	priKey3, err := blsgen.LoadBlsKeyWithPassPhrase(keyPath3, "")
+	pubKey3 := priKey3.GetPublicKey()
+	if err != nil {
+		t.Error(err)
+	}
+	keys = append(keys, pubKey3)
+	if err := GetDefaultConfig().ValidateConsensusKeysForSameShard(keys, 0); err == nil {
+		e := errors.New("bls keys do not belong to the same shard")
+		t.Error("expected", e, "got", nil)
+	}
+}