Merge pull request #1252 from nspcc-dev/fix/voting

Implement delegated voting

cli/wallet/wallet.go

@@ -13,7 +13,11 @@ import (
 	"github.com/nspcc-dev/neo-go/cli/options"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
+	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/rpc/client"
 	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/wallet"
 	"github.com/urfave/cli"
 	"golang.org/x/crypto/ssh/terminal"
@@ -186,6 +190,24 @@ func NewCommands() []cli.Command {
 				Usage:       "work with NEP5 contracts",
 				Subcommands: newNEP5Commands(),
 			},
+			{
+				Name:      "vote",
+				Usage:     "vote for a validator",
+				UsageText: "vote -w <path> -r <rpc> [-t <timeout>] [-g gas] -a <addr> -k <public key>",
+				Action:    handleVote,
+				Flags: append([]cli.Flag{
+					walletPathFlag,
+					gasFlag,
+					flags.AddressFlag{
+						Name:  "addr, a",
+						Usage: "Address to vote from",
+					},
+					cli.StringFlag{
+						Name:  "key, k",
+						Usage: "Public key of candidate to vote for",
+					},
+				}, options.RPC...),
+			},
 		},
 	}}
 }
@@ -513,6 +535,69 @@ func createWallet(ctx *cli.Context) error {
 	return nil
 }
 
+func handleVote(ctx *cli.Context) error {
+	wall, err := openWallet(ctx.String("wallet"))
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+
+	addrFlag := ctx.Generic("addr").(*flags.Address)
+	addr := addrFlag.Uint160()
+	acc := wall.GetAccount(addr)
+	if acc == nil {
+		return cli.NewExitError(fmt.Errorf("can't find account for the address: %s", addrFlag), 1)
+	}
+
+	var pub *keys.PublicKey
+	pubStr := ctx.String("key")
+	if pubStr != "" {
+		pub, err = keys.NewPublicKeyFromString(pubStr)
+		if err != nil {
+			return cli.NewExitError(fmt.Errorf("invalid public key: '%s'", pubStr), 1)
+		}
+	}
+
+	gctx, cancel := options.GetTimeoutContext(ctx)
+	defer cancel()
+
+	c, err := options.GetRPCClient(gctx, ctx)
+	if err != nil {
+		return err
+	}
+
+	var pubArg interface{}
+	if pub != nil {
+		pubArg = pub.Bytes()
+	}
+
+	gas := flags.Fixed8FromContext(ctx, "gas")
+	w := io.NewBufBinWriter()
+	emit.AppCallWithOperationAndArgs(w.BinWriter, client.NeoContractHash, "vote", addr.BytesBE(), pubArg)
+	emit.Opcode(w.BinWriter, opcode.ASSERT)
+
+	tx, err := c.CreateTxFromScript(w.Bytes(), acc, int64(gas))
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+
+	if pass, err := readPassword("Password > "); err != nil {
+		return cli.NewExitError(err, 1)
+	} else if err := acc.Decrypt(pass); err != nil {
+		return cli.NewExitError(err, 1)
+	}
+
+	if err = acc.SignTx(tx); err != nil {
+		return cli.NewExitError(fmt.Errorf("can't sign tx: %v", err), 1)
+	}
+
+	res, err := c.SendRawTransaction(tx)
+	if err != nil {
+		return cli.NewExitError(err, 1)
+	}
+	fmt.Println(res.StringLE())
+	return nil
+}
+
 func readAccountInfo() (string, string, error) {
 	buf := bufio.NewReader(os.Stdin)
 	fmt.Print("Enter the name of the account > ")

config/protocol.mainnet.yml

@@ -2,7 +2,7 @@ ProtocolConfiguration:
   Magic: 5195086
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
   - 03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c
   - 02df48f60e8f3e01c48ff40b9b7f1310d7a8b2a193188befe1c2e3df740e895093
   - 03b8d9d5771d8f513aa0869b9cc8d50986403b78c6da36890638c3d46a5adce04a
@@ -10,6 +10,7 @@ ProtocolConfiguration:
   - 024c7b7fb6c310fccf1ba33b082519d82964ea93868d676662d4a59ad548df0e7d
   - 02aaec38470f6aad0042c6e877cfd8087d2676b0f516fddd362801b9bd3936399e
   - 02486fd15702c4490a26703112a5cc1d0923fd697a33406bd5a1c00e0013b09a70
+  ValidatorsCount: 7
   SeedList:
   - seed1.neo.org:10333
   - seed2.neo.org:10333

config/protocol.privnet.docker.four.yml

@@ -2,11 +2,12 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699
     - 02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62
+  ValidatorsCount: 4
   SeedList:
     - 172.200.0.1:20333
     - 172.200.0.2:20334

config/protocol.privnet.docker.one.yml

@@ -2,11 +2,12 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699
     - 02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62
+  ValidatorsCount: 4
   SeedList:
     - 172.200.0.1:20333
     - 172.200.0.2:20334

config/protocol.privnet.docker.single.yml

@@ -2,8 +2,9 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 1
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
+  ValidatorsCount: 1
   SeedList:
     - 172.200.0.1:20333
   VerifyBlocks: true

config/protocol.privnet.docker.three.yml

@@ -2,11 +2,12 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699
     - 02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62
+  ValidatorsCount: 4
   SeedList:
     - 172.200.0.1:20333
     - 172.200.0.2:20334

config/protocol.privnet.docker.two.yml

@@ -2,11 +2,12 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699
     - 02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62
+  ValidatorsCount: 4
   SeedList:
     - 172.200.0.1:20333
     - 172.200.0.2:20334

config/protocol.privnet.yml

@@ -2,7 +2,7 @@ ProtocolConfiguration:
   Magic: 56753
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699

config/protocol.testnet.yml

@@ -2,7 +2,7 @@ ProtocolConfiguration:
   Magic: 1951352142
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
   - 023e9b32ea89b94d066e649b124fd50e396ee91369e8e2a6ae1b11c170d022256d
   - 03009b7540e10f2562e5fd8fac9eaec25166a58b26e412348ff5a86927bfac22a2
   - 02ba2c70f5996f357a43198705859fae2cfea13e1172962800772b3d588a9d4abd
@@ -10,6 +10,7 @@ ProtocolConfiguration:
   - 02a7834be9b32e2981d157cb5bbd3acb42cfd11ea5c3b10224d7a44e98c5910f1b
   - 0214baf0ceea3a66f17e7e1e839ea25fd8bed6cd82e6bb6e68250189065f44ff01
   - 030205e9cefaea5a1dfc580af20c8d5aa2468bb0148f1a5e4605fc622c80e604ba
+  ValidatorsCount: 7
   SeedList:
   - seed1t.neo.org:20333
   - seed2t.neo.org:20333

config/protocol.unit_testnet.yml

@@ -2,11 +2,12 @@ ProtocolConfiguration:
   Magic: 42
   SecondsPerBlock: 15
   MemPoolSize: 50000
-  StandbyValidators:
+  StandbyCommittee:
     - 02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2
     - 02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e
     - 03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699
     - 02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62
+  ValidatorsCount: 4
   SeedList:
     - 127.0.0.1:20334
     - 127.0.0.1:20335

pkg/config/protocol_config.go

@@ -10,10 +10,11 @@ type (
 		Magic       netmode.Magic `yaml:"Magic"`
 		MemPoolSize int           `yaml:"MemPoolSize"`
 		// SaveStorageBatch enables storage batch saving before every persist.
-		SaveStorageBatch  bool     `yaml:"SaveStorageBatch"`
+		SaveStorageBatch bool     `yaml:"SaveStorageBatch"`
-		SecondsPerBlock   int      `yaml:"SecondsPerBlock"`
+		SecondsPerBlock  int      `yaml:"SecondsPerBlock"`
-		SeedList          []string `yaml:"SeedList"`
+		SeedList         []string `yaml:"SeedList"`
-		StandbyValidators []string `yaml:"StandbyValidators"`
+		StandbyCommittee []string `yaml:"StandbyCommittee"`
+		ValidatorsCount  int      `yaml:"ValidatorsCount"`
 		// Whether to verify received blocks.
 		VerifyBlocks bool `yaml:"VerifyBlocks"`
 		// Whether to verify transactions in received blocks.

pkg/core/blockchain.go

@@ -119,7 +119,7 @@ type Blockchain struct {
 	// cache for block verification keys.
 	keyCache map[util.Uint160]map[string]*keys.PublicKey
 
-	sbValidators keys.PublicKeys
+	sbCommittee keys.PublicKeys
 
 	log *zap.Logger
 
@@ -156,7 +156,7 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 		cfg.MemPoolSize = defaultMemPoolSize
 		log.Info("mempool size is not set or wrong, setting default value", zap.Int("MemPoolSize", cfg.MemPoolSize))
 	}
-	validators, err := validatorsFromConfig(cfg)
+	committee, err := committeeFromConfig(cfg)
 	if err != nil {
 		return nil, err
 	}
@@ -169,7 +169,7 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 		runToExitCh:   make(chan struct{}),
 		memPool:       mempool.NewMemPool(cfg.MemPoolSize),
 		keyCache:      make(map[util.Uint160]map[string]*keys.PublicKey),
-		sbValidators:  validators,
+		sbCommittee:   committee,
 		log:           log,
 		events:        make(chan bcEvent),
 		subCh:         make(chan interface{}),
@@ -1393,7 +1393,12 @@ func (bc *Blockchain) PoolTx(t *transaction.Transaction) error {
 
 //GetStandByValidators returns validators from the configuration.
 func (bc *Blockchain) GetStandByValidators() keys.PublicKeys {
-	return bc.sbValidators.Copy()
+	return bc.sbCommittee[:bc.config.ValidatorsCount].Copy()
+}
+
+// GetStandByCommittee returns standby commitee from the configuration.
+func (bc *Blockchain) GetStandByCommittee() keys.PublicKeys {
+	return bc.sbCommittee.Copy()
 }
 
 // GetValidators returns current validators.
@@ -1408,7 +1413,7 @@ func (bc *Blockchain) GetNextBlockValidators() ([]*keys.PublicKey, error) {
 
 // GetEnrollments returns all registered validators.
 func (bc *Blockchain) GetEnrollments() ([]state.Validator, error) {
-	return bc.contracts.NEO.GetRegisteredValidators(bc.dao)
+	return bc.contracts.NEO.GetCandidates(bc.dao)
 }
 
 // GetScriptHashesForVerifying returns all the ScriptHashes of a transaction which will be use

pkg/core/blockchainer/blockchainer.go

@@ -42,6 +42,7 @@ type Blockchainer interface {
 	GetNEP5TransferLog(util.Uint160) *state.NEP5TransferLog
 	GetNEP5Balances(util.Uint160) *state.NEP5Balances
 	GetValidators() ([]*keys.PublicKey, error)
+	GetStandByCommittee() keys.PublicKeys
 	GetStandByValidators() keys.PublicKeys
 	GetScriptHashesForVerifying(*transaction.Transaction) ([]util.Uint160, error)
 	GetStateRoot(height uint32) (*state.MPTRootState, error)

pkg/core/helper_test.go

@@ -394,7 +394,7 @@ func addSigners(txs ...*transaction.Transaction) {
 
 func signTx(bc *Blockchain, txs ...*transaction.Transaction) error {
 	validators := bc.GetStandByValidators()
-	rawScript, err := smartcontract.CreateMultiSigRedeemScript(len(bc.config.StandbyValidators)/2+1, validators)
+	rawScript, err := smartcontract.CreateMultiSigRedeemScript(bc.config.ValidatorsCount/2+1, validators)
 	if err != nil {
 		return errors.Wrap(err, "fail to sign tx")
 	}

pkg/core/native/native_gas.go

@@ -70,7 +70,7 @@ func (g *GAS) Initialize(ic *interop.Context) error {
 	if err := g.nep5TokenNative.Initialize(ic); err != nil {
 		return err
 	}
-	if g.nep5TokenNative.getTotalSupply(ic).Sign() != 0 {
+	if g.nep5TokenNative.getTotalSupply(ic.DAO).Sign() != 0 {
 		return errors.New("already initialized")
 	}
 	h, _, err := getStandbyValidatorsHash(ic)

pkg/core/native/native_neo.go

@@ -42,14 +42,16 @@ const (
 	neoContractID = -1
 	// NEOTotalSupply is the total amount of NEO in the system.
 	NEOTotalSupply = 100000000
-	// prefixValidator is a prefix used to store validator's data.
+	// prefixCandidate is a prefix used to store validator's data.
-	prefixValidator = 33
+	prefixCandidate = 33
+	// prefixVotersCount is a prefix for storing total amount of NEO of voters.
+	prefixVotersCount = 1
+	// effectiveVoterTurnout represents minimal ratio of total supply to total amount voted value
+	// which is require to use non-standby validators.
+	effectiveVoterTurnout = 5
 )
 
 var (
-	// validatorsCountKey is a key used to store validators count
-	// used to determine the real number of validators.
-	validatorsCountKey = []byte{15}
 	// nextValidatorsKey is a key used to store validators for the
 	// next block.
 	nextValidatorsKey = []byte{14}
@@ -61,7 +63,7 @@ func makeValidatorKey(key *keys.PublicKey) []byte {
 	// Don't create a new buffer.
 	b = append(b, 0)
 	copy(b[1:], b[0:])
-	b[0] = prefixValidator
+	b[0] = prefixCandidate
 	return b
 }
 
@@ -89,19 +91,28 @@ func NewNEO() *NEO {
 	md := newMethodAndPrice(n.unclaimedGas, 3000000, smartcontract.AllowStates)
 	n.AddMethod(md, desc, true)
 
-	desc = newDescriptor("registerValidator", smartcontract.BoolType,
+	desc = newDescriptor("registerCandidate", smartcontract.BoolType,
 		manifest.NewParameter("pubkey", smartcontract.PublicKeyType))
-	md = newMethodAndPrice(n.registerValidator, 5000000, smartcontract.AllowModifyStates)
+	md = newMethodAndPrice(n.registerCandidate, 5000000, smartcontract.AllowModifyStates)
+	n.AddMethod(md, desc, false)
+
+	desc = newDescriptor("unregisterCandidate", smartcontract.BoolType,
+		manifest.NewParameter("pubkey", smartcontract.PublicKeyType))
+	md = newMethodAndPrice(n.unregisterCandidate, 5000000, smartcontract.AllowModifyStates)
 	n.AddMethod(md, desc, false)
 
 	desc = newDescriptor("vote", smartcontract.BoolType,
 		manifest.NewParameter("account", smartcontract.Hash160Type),
-		manifest.NewParameter("pubkeys", smartcontract.ArrayType))
+		manifest.NewParameter("pubkey", smartcontract.PublicKeyType))
 	md = newMethodAndPrice(n.vote, 500000000, smartcontract.AllowModifyStates)
 	n.AddMethod(md, desc, false)
 
-	desc = newDescriptor("getRegisteredValidators", smartcontract.ArrayType)
+	desc = newDescriptor("getCandidates", smartcontract.ArrayType)
-	md = newMethodAndPrice(n.getRegisteredValidatorsCall, 100000000, smartcontract.AllowStates)
+	md = newMethodAndPrice(n.getCandidatesCall, 100000000, smartcontract.AllowStates)
+	n.AddMethod(md, desc, true)
+
+	desc = newDescriptor("getСommittee", smartcontract.ArrayType)
+	md = newMethodAndPrice(n.getCommittee, 100000000, smartcontract.AllowStates)
 	n.AddMethod(md, desc, true)
 
 	desc = newDescriptor("getValidators", smartcontract.ArrayType)
@@ -121,7 +132,7 @@ func (n *NEO) Initialize(ic *interop.Context) error {
 		return err
 	}
 
-	if n.nep5TokenNative.getTotalSupply(ic).Sign() != 0 {
+	if n.nep5TokenNative.getTotalSupply(ic.DAO).Sign() != 0 {
 		return errors.New("already initialized")
 	}
 
@@ -131,8 +142,13 @@ func (n *NEO) Initialize(ic *interop.Context) error {
 	}
 	n.mint(ic, h, big.NewInt(NEOTotalSupply))
 
+	err = ic.DAO.PutStorageItem(n.ContractID, []byte{prefixVotersCount}, &state.StorageItem{Value: []byte{0}})
+	if err != nil {
+		return err
+	}
+
 	for i := range vs {
-		if err := n.registerValidatorInternal(ic, vs[i]); err != nil {
+		if err := n.RegisterCandidateInternal(ic, vs[i]); err != nil {
 			return err
 		}
 	}
@@ -166,21 +182,11 @@ func (n *NEO) increaseBalance(ic *interop.Context, h util.Uint160, si *state.Sto
 		si.Value = acc.Bytes()
 		return nil
 	}
-	if len(acc.Votes) > 0 {
+	if err := n.ModifyAccountVotes(acc, ic.DAO, amount, modifyVoteTransfer); err != nil {
-		if err := n.ModifyAccountVotes(acc, ic.DAO, amount); err != nil {
+		return err
-			return err
+	}
-		}
+	if acc.VoteTo != nil {
-		siVC := ic.DAO.GetStorageItem(n.ContractID, validatorsCountKey)
+		if err := n.modifyVoterTurnout(ic.DAO, amount); err != nil {
-		if siVC == nil {
-			return errors.New("validators count uninitialized")
-		}
-		vc, err := ValidatorsCountFromBytes(siVC.Value)
-		if err != nil {
-			return err
-		}
-		vc[len(acc.Votes)-1].Add(&vc[len(acc.Votes)-1], amount)
-		siVC.Value = vc.Bytes()
-		if err := ic.DAO.PutStorageItem(n.ContractID, validatorsCountKey, siVC); err != nil {
 			return err
 		}
 	}
@@ -216,43 +222,74 @@ func (n *NEO) unclaimedGas(ic *interop.Context, args []stackitem.Item) stackitem
 	return stackitem.NewBigInteger(gen)
 }
 
-func (n *NEO) registerValidator(ic *interop.Context, args []stackitem.Item) stackitem.Item {
+func (n *NEO) registerCandidate(ic *interop.Context, args []stackitem.Item) stackitem.Item {
-	err := n.registerValidatorInternal(ic, toPublicKey(args[0]))
+	pub := toPublicKey(args[0])
+	ok, err := runtime.CheckKeyedWitness(ic, pub)
+	if err != nil {
+		panic(err)
+	} else if !ok {
+		return stackitem.NewBool(false)
+	}
+	err = n.RegisterCandidateInternal(ic, pub)
 	return stackitem.NewBool(err == nil)
 }
 
-func (n *NEO) registerValidatorInternal(ic *interop.Context, pub *keys.PublicKey) error {
+// RegisterCandidateInternal registers pub as a new candidate.
+func (n *NEO) RegisterCandidateInternal(ic *interop.Context, pub *keys.PublicKey) error {
 	key := makeValidatorKey(pub)
 	si := ic.DAO.GetStorageItem(n.ContractID, key)
-	if si != nil {
+	if si == nil {
-		return errors.New("already registered")
+		c := &candidate{Registered: true}
+		si = &state.StorageItem{Value: c.Bytes()}
+	} else {
+		c := new(candidate).FromBytes(si.Value)
+		c.Registered = true
+		si.Value = c.Bytes()
 	}
-	si = new(state.StorageItem)
+	return ic.DAO.PutStorageItem(n.ContractID, key, si)
-	// Zero value.
+}
-	si.Value = []byte{}
+
+func (n *NEO) unregisterCandidate(ic *interop.Context, args []stackitem.Item) stackitem.Item {
+	pub := toPublicKey(args[0])
+	ok, err := runtime.CheckKeyedWitness(ic, pub)
+	if err != nil {
+		panic(err)
+	} else if !ok {
+		return stackitem.NewBool(false)
+	}
+	err = n.UnregisterCandidateInternal(ic, pub)
+	return stackitem.NewBool(err == nil)
+}
+
+// UnregisterCandidateInternal unregisters pub as a candidate.
+func (n *NEO) UnregisterCandidateInternal(ic *interop.Context, pub *keys.PublicKey) error {
+	key := makeValidatorKey(pub)
+	si := ic.DAO.GetStorageItem(n.ContractID, key)
+	if si == nil {
+		return nil
+	}
+	n.validators.Store(keys.PublicKeys(nil))
+	c := new(candidate).FromBytes(si.Value)
+	if c.Votes.Sign() == 0 {
+		return ic.DAO.DeleteStorageItem(n.ContractID, key)
+	}
+	c.Registered = false
+	si.Value = c.Bytes()
 	return ic.DAO.PutStorageItem(n.ContractID, key, si)
 }
 
 func (n *NEO) vote(ic *interop.Context, args []stackitem.Item) stackitem.Item {
 	acc := toUint160(args[0])
-	arr := args[1].Value().([]stackitem.Item)
+	var pub *keys.PublicKey
-	var pubs keys.PublicKeys
+	if _, ok := args[1].(stackitem.Null); !ok {
-	for i := range arr {
+		pub = toPublicKey(args[1])
-		pub := new(keys.PublicKey)
-		bs, err := arr[i].TryBytes()
-		if err != nil {
-			panic(err)
-		} else if err := pub.DecodeBytes(bs); err != nil {
-			panic(err)
-		}
-		pubs = append(pubs, pub)
 	}
-	err := n.VoteInternal(ic, acc, pubs)
+	err := n.VoteInternal(ic, acc, pub)
 	return stackitem.NewBool(err == nil)
 }
 
 // VoteInternal votes from account h for validarors specified in pubs.
-func (n *NEO) VoteInternal(ic *interop.Context, h util.Uint160, pubs keys.PublicKeys) error {
+func (n *NEO) VoteInternal(ic *interop.Context, h util.Uint160, pub *keys.PublicKey) error {
 	ok, err := runtime.CheckHashedWitness(ic, h)
 	if err != nil {
 		return err
@@ -268,90 +305,80 @@ func (n *NEO) VoteInternal(ic *interop.Context, h util.Uint160, pubs keys.Public
 	if err != nil {
 		return err
 	}
-	if err := n.ModifyAccountVotes(acc, ic.DAO, new(big.Int).Neg(&acc.Balance)); err != nil {
+	if (acc.VoteTo == nil) != (pub == nil) {
-		return err
+		val := &acc.Balance
-	}
+		if pub == nil {
-	pubs = pubs.Unique()
+			val = new(big.Int).Neg(val)
-	// Check validators registration.
-	var newPubs keys.PublicKeys
-	for _, pub := range pubs {
-		if ic.DAO.GetStorageItem(n.ContractID, makeValidatorKey(pub)) == nil {
-			continue
 		}
-		newPubs = append(newPubs, pub)
+		if err := n.modifyVoterTurnout(ic.DAO, val); err != nil {
-	}
-	if lp, lv := len(newPubs), len(acc.Votes); lp != lv {
-		var si *state.StorageItem
-		var vc *ValidatorsCount
-		var err error
-
-		si = ic.DAO.GetStorageItem(n.ContractID, validatorsCountKey)
-		if si == nil {
-			// The first voter.
-			si = new(state.StorageItem)
-			vc = new(ValidatorsCount)
-		} else {
-			vc, err = ValidatorsCountFromBytes(si.Value)
-			if err != nil {
-				return err
-			}
-		}
-		if lv > 0 {
-			vc[lv-1].Sub(&vc[lv-1], &acc.Balance)
-		}
-		if len(newPubs) > 0 {
-			vc[lp-1].Add(&vc[lp-1], &acc.Balance)
-		}
-		si.Value = vc.Bytes()
-		if err := ic.DAO.PutStorageItem(n.ContractID, validatorsCountKey, si); err != nil {
 			return err
 		}
 	}
-	acc.Votes = newPubs
+	if err := n.ModifyAccountVotes(acc, ic.DAO, new(big.Int).Neg(&acc.Balance), modifyVoteOld); err != nil {
-	if err := n.ModifyAccountVotes(acc, ic.DAO, &acc.Balance); err != nil {
+		return err
+	}
+	acc.VoteTo = pub
+	if err := n.ModifyAccountVotes(acc, ic.DAO, &acc.Balance, modifyVoteNew); err != nil {
 		return err
 	}
 	si.Value = acc.Bytes()
 	return ic.DAO.PutStorageItem(n.ContractID, key, si)
 }
 
+const (
+	modifyVoteTransfer = iota
+	modifyVoteOld
+	modifyVoteNew
+)
+
 // ModifyAccountVotes modifies votes of the specified account by value (can be negative).
-func (n *NEO) ModifyAccountVotes(acc *state.NEOBalanceState, d dao.DAO, value *big.Int) error {
+// typ specifies if this modify is occuring during transfer or vote (with old or new validator).
-	for _, vote := range acc.Votes {
+func (n *NEO) ModifyAccountVotes(acc *state.NEOBalanceState, d dao.DAO, value *big.Int, typ int) error {
-		key := makeValidatorKey(vote)
+	if acc.VoteTo != nil {
+		key := makeValidatorKey(acc.VoteTo)
 		si := d.GetStorageItem(n.ContractID, key)
 		if si == nil {
 			return errors.New("invalid validator")
 		}
-		votes := bigint.FromBytes(si.Value)
+		cd := new(candidate).FromBytes(si.Value)
-		votes.Add(votes, value)
+		cd.Votes.Add(&cd.Votes, value)
-		si.Value = bigint.ToPreallocatedBytes(votes, si.Value[:0])
+		switch typ {
-		if err := d.PutStorageItem(n.ContractID, key, si); err != nil {
+		case modifyVoteOld:
-			return err
+			if !cd.Registered && cd.Votes.Sign() == 0 {
+				return d.DeleteStorageItem(n.ContractID, key)
+			}
+		case modifyVoteNew:
+			if !cd.Registered {
+				return errors.New("validator must be registered")
+			}
 		}
+		n.validators.Store(keys.PublicKeys(nil))
+		si.Value = cd.Bytes()
+		return d.PutStorageItem(n.ContractID, key, si)
 	}
-	n.validators.Store(keys.PublicKeys(nil))
 	return nil
 }
 
-func (n *NEO) getRegisteredValidators(d dao.DAO) ([]keyWithVotes, error) {
+func (n *NEO) getCandidates(d dao.DAO) ([]keyWithVotes, error) {
-	siMap, err := d.GetStorageItemsWithPrefix(n.ContractID, []byte{prefixValidator})
+	siMap, err := d.GetStorageItemsWithPrefix(n.ContractID, []byte{prefixCandidate})
 	if err != nil {
 		return nil, err
 	}
 	arr := make([]keyWithVotes, 0, len(siMap))
 	for key, si := range siMap {
-		votes := bigint.FromBytes(si.Value)
+		c := new(candidate).FromBytes(si.Value)
-		arr = append(arr, keyWithVotes{key, votes})
+		if c.Registered {
+			arr = append(arr, keyWithVotes{key, &c.Votes})
+		}
 	}
 	sort.Slice(arr, func(i, j int) bool { return strings.Compare(arr[i].Key, arr[j].Key) == -1 })
 	return arr, nil
 }
 
-// GetRegisteredValidators returns current registered validators list with keys
+// GetCandidates returns current registered validators list with keys
 // and votes.
-func (n *NEO) GetRegisteredValidators(d dao.DAO) ([]state.Validator, error) {
+func (n *NEO) GetCandidates(d dao.DAO) ([]state.Validator, error) {
-	kvs, err := n.getRegisteredValidators(d)
+	kvs, err := n.getCandidates(d)
 	if err != nil {
 		return nil, err
 	}
@@ -366,8 +393,8 @@ func (n *NEO) GetRegisteredValidators(d dao.DAO) ([]state.Validator, error) {
 	return arr, nil
 }
 
-func (n *NEO) getRegisteredValidatorsCall(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
+func (n *NEO) getCandidatesCall(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
-	validators, err := n.getRegisteredValidators(ic.DAO)
+	validators, err := n.getCandidates(ic.DAO)
 	if err != nil {
 		panic(err)
 	}
@@ -386,53 +413,15 @@ func (n *NEO) GetValidatorsInternal(bc blockchainer.Blockchainer, d dao.DAO) (ke
 	if vals := n.validators.Load().(keys.PublicKeys); vals != nil {
 		return vals.Copy(), nil
 	}
-	standByValidators := bc.GetStandByValidators()
+	result, err := n.getCommitteeMembers(bc, d)
-	si := d.GetStorageItem(n.ContractID, validatorsCountKey)
-	if si == nil {
-		n.validators.Store(standByValidators)
-		return standByValidators.Copy(), nil
-	}
-	validatorsCount, err := ValidatorsCountFromBytes(si.Value)
 	if err != nil {
 		return nil, err
 	}
-	validators, err := n.GetRegisteredValidators(d)
+	count := bc.GetConfig().ValidatorsCount
-	if err != nil {
+	if len(result) < count {
-		return nil, err
+		count = len(result)
 	}
-	sort.Slice(validators, func(i, j int) bool {
+	result = result[:count]
-		// The most-voted validators should end up in the front of the list.
-		cmp := validators[i].Votes.Cmp(validators[j].Votes)
-		if cmp != 0 {
-			return cmp > 0
-		}
-		// Ties are broken with public keys.
-		return validators[i].Key.Cmp(validators[j].Key) == -1
-	})
-
-	count := validatorsCount.GetWeightedAverage()
-	if count < len(standByValidators) {
-		count = len(standByValidators)
-	}
-
-	uniqueSBValidators := standByValidators.Unique()
-	result := keys.PublicKeys{}
-	for _, validator := range validators {
-		if validator.Votes.Sign() > 0 || uniqueSBValidators.Contains(validator.Key) {
-			result = append(result, validator.Key)
-		}
-	}
-
-	if result.Len() >= count {
-		result = result[:count]
-	} else {
-		for i := 0; i < uniqueSBValidators.Len() && result.Len() < count; i++ {
-			if !result.Contains(uniqueSBValidators[i]) {
-				result = append(result, uniqueSBValidators[i])
-			}
-		}
-	}
-	sort.Sort(result)
 	n.validators.Store(result)
 	return result, nil
 }
@@ -445,6 +434,68 @@ func (n *NEO) getValidators(ic *interop.Context, _ []stackitem.Item) stackitem.I
 	return pubsToArray(result)
 }
 
+func (n *NEO) getCommittee(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
+	pubs, err := n.getCommitteeMembers(ic.Chain, ic.DAO)
+	if err != nil {
+		panic(err)
+	}
+	sort.Sort(pubs)
+	return pubsToArray(pubs)
+}
+
+func (n *NEO) modifyVoterTurnout(d dao.DAO, amount *big.Int) error {
+	key := []byte{prefixVotersCount}
+	si := d.GetStorageItem(n.ContractID, key)
+	if si == nil {
+		return errors.New("voters count not found")
+	}
+	votersCount := bigint.FromBytes(si.Value)
+	votersCount.Add(votersCount, amount)
+	si.Value = bigint.ToBytes(votersCount)
+	return d.PutStorageItem(n.ContractID, key, si)
+}
+
+func (n *NEO) getCommitteeMembers(bc blockchainer.Blockchainer, d dao.DAO) (keys.PublicKeys, error) {
+	key := []byte{prefixVotersCount}
+	si := d.GetStorageItem(n.ContractID, key)
+	if si == nil {
+		return nil, errors.New("voters count not found")
+	}
+	votersCount := bigint.FromBytes(si.Value)
+	// votersCount / totalSupply must be >= 0.2
+	votersCount.Mul(votersCount, big.NewInt(effectiveVoterTurnout))
+	voterTurnout := votersCount.Div(votersCount, n.getTotalSupply(d))
+	if voterTurnout.Sign() != 1 {
+		return bc.GetStandByValidators(), nil
+	}
+	cs, err := n.getCandidates(d)
+	if err != nil {
+		return nil, err
+	}
+	sbVals := bc.GetStandByValidators()
+	count := len(sbVals)
+	if len(cs) < count {
+		return sbVals, nil
+	}
+	sort.Slice(cs, func(i, j int) bool {
+		// The most-voted validators should end up in the front of the list.
+		cmp := cs[i].Votes.Cmp(cs[j].Votes)
+		if cmp != 0 {
+			return cmp > 0
+		}
+		// Ties are broken with public keys.
+		return strings.Compare(cs[i].Key, cs[j].Key) == -1
+	})
+	pubs := make(keys.PublicKeys, count)
+	for i := range pubs {
+		pubs[i], err = keys.NewPublicKeyFromBytes([]byte(cs[i].Key), elliptic.P256())
+		if err != nil {
+			return nil, err
+		}
+	}
+	return pubs, nil
+}
+
 func (n *NEO) getNextBlockValidators(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
 	result, err := n.getNextBlockValidatorsInternal(ic.Chain, ic.DAO)
 	if err != nil {

pkg/core/native/native_neo_candidate.go

@@ -0,0 +1,48 @@
+package native
+
+import (
+	"math/big"
+
+	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+type candidate struct {
+	Registered bool
+	Votes      big.Int
+}
+
+// Bytes marshals c to byte array.
+func (c *candidate) Bytes() []byte {
+	w := io.NewBufBinWriter()
+	stackitem.EncodeBinaryStackItem(c.toStackItem(), w.BinWriter)
+	return w.Bytes()
+}
+
+// FromBytes unmarshals candidate from byte array.
+func (c *candidate) FromBytes(data []byte) *candidate {
+	r := io.NewBinReaderFromBuf(data)
+	item := stackitem.DecodeBinaryStackItem(r)
+	if r.Err != nil {
+		panic(r.Err)
+	}
+	return c.fromStackItem(item)
+}
+
+func (c *candidate) toStackItem() stackitem.Item {
+	return stackitem.NewStruct([]stackitem.Item{
+		stackitem.NewBool(c.Registered),
+		stackitem.NewBigInteger(&c.Votes),
+	})
+}
+
+func (c *candidate) fromStackItem(item stackitem.Item) *candidate {
+	arr := item.(*stackitem.Struct).Value().([]stackitem.Item)
+	vs, err := arr[1].TryInteger()
+	if err != nil {
+		panic(err)
+	}
+	c.Registered = arr[0].Bool()
+	c.Votes = *vs
+	return c
+}

pkg/core/native/native_neo_test.go

@@ -0,0 +1,18 @@
+package native
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCandidate_Bytes(t *testing.T) {
+	expected := &candidate{
+		Registered: true,
+		Votes:      *big.NewInt(0x0F),
+	}
+	data := expected.Bytes()
+	actual := new(candidate).FromBytes(data)
+	require.Equal(t, expected, actual)
+}

pkg/core/native/native_nep5.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"math/big"
 
+	"github.com/nspcc-dev/neo-go/pkg/core/dao"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
@@ -104,27 +105,27 @@ func (c *nep5TokenNative) Decimals(_ *interop.Context, _ []stackitem.Item) stack
 }
 
 func (c *nep5TokenNative) TotalSupply(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
-	return stackitem.NewBigInteger(c.getTotalSupply(ic))
+	return stackitem.NewBigInteger(c.getTotalSupply(ic.DAO))
 }
 
-func (c *nep5TokenNative) getTotalSupply(ic *interop.Context) *big.Int {
+func (c *nep5TokenNative) getTotalSupply(d dao.DAO) *big.Int {
-	si := ic.DAO.GetStorageItem(c.ContractID, totalSupplyKey)
+	si := d.GetStorageItem(c.ContractID, totalSupplyKey)
 	if si == nil {
 		return big.NewInt(0)
 	}
 	return bigint.FromBytes(si.Value)
 }
 
-func (c *nep5TokenNative) saveTotalSupply(ic *interop.Context, supply *big.Int) error {
+func (c *nep5TokenNative) saveTotalSupply(d dao.DAO, supply *big.Int) error {
 	si := &state.StorageItem{Value: bigint.ToBytes(supply)}
-	return ic.DAO.PutStorageItem(c.ContractID, totalSupplyKey, si)
+	return d.PutStorageItem(c.ContractID, totalSupplyKey, si)
 }
 
 func (c *nep5TokenNative) Transfer(ic *interop.Context, args []stackitem.Item) stackitem.Item {
 	from := toUint160(args[0])
 	to := toUint160(args[1])
 	amount := toBigInt(args[2])
-	err := c.transfer(ic, from, to, amount)
+	err := c.TransferInternal(ic, from, to, amount)
 	return stackitem.NewBool(err == nil)
 }
 
@@ -170,7 +171,8 @@ func (c *nep5TokenNative) updateAccBalance(ic *interop.Context, acc util.Uint160
 	return err
 }
 
-func (c *nep5TokenNative) transfer(ic *interop.Context, from, to util.Uint160, amount *big.Int) error {
+// TransferInternal transfers NEO between accounts.
+func (c *nep5TokenNative) TransferInternal(ic *interop.Context, from, to util.Uint160, amount *big.Int) error {
 	if amount.Sign() == -1 {
 		return errors.New("negative amount")
 	}
@@ -248,9 +250,9 @@ func (c *nep5TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount
 		panic(err)
 	}
 
-	supply := c.getTotalSupply(ic)
+	supply := c.getTotalSupply(ic.DAO)
 	supply.Add(supply, amount)
-	err := c.saveTotalSupply(ic, supply)
+	err := c.saveTotalSupply(ic.DAO, supply)
 	if err != nil {
 		panic(err)
 	}

pkg/core/native/validators_count.go

@@ -63,51 +63,3 @@ func (vc *ValidatorsCount) DecodeBinary(r *io.BinReader) {
 		vc[i] = *bigint.FromBytes(buf)
 	}
 }
-
-// GetWeightedAverage returns an average count of validators that's been voted
-// for not counting 1/4 of minimum and maximum numbers.
-func (vc *ValidatorsCount) GetWeightedAverage() int {
-	const (
-		lowerThreshold = 0.25
-		upperThreshold = 0.75
-	)
-	var (
-		sumWeight, sumValue, overallSum, slidingSum int64
-		slidingRatio                                float64
-	)
-
-	for i := range vc {
-		overallSum += vc[i].Int64()
-	}
-
-	for i := range vc {
-		if slidingRatio >= upperThreshold {
-			break
-		}
-		weight := vc[i].Int64()
-		slidingSum += weight
-		previousRatio := slidingRatio
-		slidingRatio = float64(slidingSum) / float64(overallSum)
-
-		if slidingRatio <= lowerThreshold {
-			continue
-		}
-
-		if previousRatio < lowerThreshold {
-			if slidingRatio > upperThreshold {
-				weight = int64((upperThreshold - lowerThreshold) * float64(overallSum))
-			} else {
-				weight = int64((slidingRatio - lowerThreshold) * float64(overallSum))
-			}
-		} else if slidingRatio > upperThreshold {
-			weight = int64((upperThreshold - previousRatio) * float64(overallSum))
-		}
-		sumWeight += weight
-		// Votes with N values get stored with N-1 index, thus +1 here.
-		sumValue += (int64(i) + 1) * weight
-	}
-	if sumValue == 0 || sumWeight == 0 {
-		return 0
-	}
-	return int(sumValue / sumWeight)
-}

pkg/core/native_neo_test.go

@@ -0,0 +1,104 @@
+package core
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
+	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
+	"github.com/nspcc-dev/neo-go/pkg/internal/testchain"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/stretchr/testify/require"
+)
+
+// testScriptGetter is an auxilliary struct to pass CheckWitness checks.
+type testScriptGetter struct {
+	h util.Uint160
+}
+
+func (t testScriptGetter) GetCallingScriptHash() util.Uint160 { return t.h }
+func (t testScriptGetter) GetEntryScriptHash() util.Uint160   { return t.h }
+func (t testScriptGetter) GetCurrentScriptHash() util.Uint160 { return t.h }
+
+func setSigner(tx *transaction.Transaction, h util.Uint160) {
+	tx.Signers = []transaction.Signer{{
+		Account: h,
+		Scopes:  transaction.Global,
+	}}
+}
+
+func TestNEO_Vote(t *testing.T) {
+	bc := newTestChain(t)
+	defer bc.Close()
+
+	neo := bc.contracts.NEO
+	tx := transaction.New(netmode.UnitTestNet, []byte{}, 0)
+	ic := bc.newInteropContext(trigger.System, bc.dao, nil, tx)
+
+	pubs, err := neo.GetValidatorsInternal(bc, ic.DAO)
+	require.NoError(t, err)
+	require.Equal(t, bc.GetStandByValidators(), pubs)
+
+	sz := testchain.Size()
+
+	candidates := make(keys.PublicKeys, sz)
+	for i := 0; i < sz; i++ {
+		priv, err := keys.NewPrivateKey()
+		require.NoError(t, err)
+		candidates[i] = priv.PublicKey()
+		if i > 0 {
+			require.NoError(t, neo.RegisterCandidateInternal(ic, candidates[i]))
+		}
+	}
+
+	for i := 0; i < sz; i++ {
+		to := testchain.PrivateKeyByID(i).GetScriptHash()
+		ic.ScriptGetter = testScriptGetter{testchain.MultisigScriptHash()}
+		require.NoError(t, neo.TransferInternal(ic, testchain.MultisigScriptHash(), to, big.NewInt(int64(sz-i)*10000000)))
+	}
+
+	for i := 1; i < sz; i++ {
+		h := testchain.PrivateKeyByID(i).GetScriptHash()
+		setSigner(tx, h)
+		ic.ScriptGetter = testScriptGetter{h}
+		require.NoError(t, neo.VoteInternal(ic, h, candidates[i]))
+	}
+
+	// First 3 validators must be the ones we have voted for.
+	pubs, err = neo.GetValidatorsInternal(bc, ic.DAO)
+	require.NoError(t, err)
+	for i := 1; i < sz; i++ {
+		require.Equal(t, pubs[i-1], candidates[i])
+	}
+
+	var ok bool
+	for _, p := range bc.GetStandByValidators() {
+		if pubs[sz-1].Equal(p) {
+			ok = true
+			break
+		}
+	}
+	require.True(t, ok, "last validator must be stand by")
+
+	// Register and give some value to the last validator.
+	require.NoError(t, neo.RegisterCandidateInternal(ic, candidates[0]))
+	h := testchain.PrivateKeyByID(0).GetScriptHash()
+	setSigner(tx, h)
+	ic.ScriptGetter = testScriptGetter{h}
+	require.NoError(t, neo.VoteInternal(ic, h, candidates[0]))
+
+	pubs, err = neo.GetValidatorsInternal(bc, ic.DAO)
+	require.NoError(t, err)
+	require.Equal(t, candidates, pubs)
+
+	require.NoError(t, neo.UnregisterCandidateInternal(ic, candidates[0]))
+	require.Error(t, neo.VoteInternal(ic, h, candidates[0]))
+
+	pubs, err = neo.GetValidatorsInternal(bc, ic.DAO)
+	require.NoError(t, err)
+	for i := range pubs {
+		require.NotEqual(t, candidates[0], pubs[i])
+	}
+}

pkg/core/state/native_state.go

@@ -1,6 +1,7 @@
 package state
 
 import (
+	"crypto/elliptic"
 	"math/big"
 
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -17,7 +18,7 @@ type NEP5BalanceState struct {
 type NEOBalanceState struct {
 	NEP5BalanceState
 	BalanceHeight uint32
-	Votes         keys.PublicKeys
+	VoteTo        *keys.PublicKey
 }
 
 // NEP5BalanceStateFromBytes converts serialized NEP5BalanceState to structure.
@@ -110,7 +111,11 @@ func (s *NEOBalanceState) DecodeBinary(r *io.BinReader) {
 func (s *NEOBalanceState) toStackItem() stackitem.Item {
 	result := s.NEP5BalanceState.toStackItem().(*stackitem.Struct)
 	result.Append(stackitem.NewBigInteger(big.NewInt(int64(s.BalanceHeight))))
-	result.Append(stackitem.NewByteArray(s.Votes.Bytes()))
+	if s.VoteTo != nil {
+		result.Append(stackitem.NewByteArray(s.VoteTo.Bytes()))
+	} else {
+		result.Append(stackitem.Null{})
+	}
 	return result
 }
 
@@ -118,6 +123,18 @@ func (s *NEOBalanceState) fromStackItem(item stackitem.Item) error {
 	structItem := item.Value().([]stackitem.Item)
 	s.Balance = *structItem[0].Value().(*big.Int)
 	s.BalanceHeight = uint32(structItem[1].Value().(*big.Int).Int64())
-	s.Votes = make(keys.PublicKeys, 0)
+	if _, ok := structItem[2].(stackitem.Null); ok {
-	return s.Votes.DecodeBytes(structItem[2].Value().([]byte))
+		s.VoteTo = nil
+		return nil
+	}
+	bs, err := structItem[2].TryBytes()
+	if err != nil {
+		return err
+	}
+	pub, err := keys.NewPublicKeyFromBytes(bs, elliptic.P256())
+	if err != nil {
+		return err
+	}
+	s.VoteTo = pub
+	return nil
 }

pkg/core/util.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"errors"
 	"time"
 
 	"github.com/nspcc-dev/neo-go/pkg/config"
@@ -94,9 +95,20 @@ func deployNativeContracts(magic netmode.Magic) *transaction.Transaction {
 }
 
 func validatorsFromConfig(cfg config.ProtocolConfiguration) ([]*keys.PublicKey, error) {
-	validators := make([]*keys.PublicKey, len(cfg.StandbyValidators))
+	vs, err := committeeFromConfig(cfg)
-	for i, pubKeyStr := range cfg.StandbyValidators {
+	if err != nil {
-		pubKey, err := keys.NewPublicKeyFromString(pubKeyStr)
+		return nil, err
+	}
+	return vs[:cfg.ValidatorsCount], nil
+}
+
+func committeeFromConfig(cfg config.ProtocolConfiguration) ([]*keys.PublicKey, error) {
+	if len(cfg.StandbyCommittee) < cfg.ValidatorsCount {
+		return nil, errors.New("validators count can be less than the size of StandbyCommittee")
+	}
+	validators := make([]*keys.PublicKey, len(cfg.StandbyCommittee))
+	for i := range validators {
+		pubKey, err := keys.NewPublicKeyFromString(cfg.StandbyCommittee[i])
 		if err != nil {
 			return nil, err
 		}

pkg/network/helper_test.go

@@ -103,6 +103,9 @@ func (chain testChain) GetNEP5Balances(util.Uint160) *state.NEP5Balances {
 func (chain testChain) GetValidators() ([]*keys.PublicKey, error) {
 	panic("TODO")
 }
+func (chain testChain) GetStandByCommittee() keys.PublicKeys {
+	panic("TODO")
+}
 func (chain testChain) GetStandByValidators() keys.PublicKeys {
 	panic("TODO")
 }

pkg/rpc/client/nep5.go

@@ -131,8 +131,15 @@ func (c *Client) CreateNEP5MultiTransferTx(acc *wallet.Account, gas int64, recep
 			recepients[i].Address, recepients[i].Amount)
 		emit.Opcode(w.BinWriter, opcode.ASSERT)
 	}
+	return c.CreateTxFromScript(w.Bytes(), acc, gas)
+}
 
-	script := w.Bytes()
+// CreateTxFromScript creates transaction and properly sets cosigners and NetworkFee.
+func (c *Client) CreateTxFromScript(script []byte, acc *wallet.Account, gas int64) (*transaction.Transaction, error) {
+	from, err := address.StringToUint160(acc.Address)
+	if err != nil {
+		return nil, fmt.Errorf("bad account address: %v", err)
+	}
 	result, err := c.InvokeScript(script, []transaction.Signer{
 		{
 			Account: from,

pkg/rpc/server/server_test.go

@@ -1125,7 +1125,6 @@ func checkNep5Transfers(t *testing.T, e *executor, acc interface{}) {
 				TxHash:    b.Hash(),
 			})
 		}
-
 	}
 	require.Equal(t, expected.Address, res.Address)
 	require.ElementsMatch(t, expected.Sent, res.Sent)

pkg/vm/emit/emit.go

@@ -79,8 +79,11 @@ func Array(w *io.BinWriter, es ...interface{}) {
 		case bool:
 			Bool(w, e)
 		default:
-			w.Err = errors.New("unsupported type")
+			if es[i] != nil {
-			return
+				w.Err = errors.New("unsupported type")
+				return
+			}
+			Opcode(w, opcode.PUSHNULL)
 		}
 	}
 	Int(w, int64(len(es)))

pkg/vm/emit/emit_test.go

@@ -142,7 +142,7 @@ func TestBytes(t *testing.T) {
 func TestEmitArray(t *testing.T) {
 	t.Run("good", func(t *testing.T) {
 		buf := io.NewBufBinWriter()
-		Array(buf.BinWriter, int64(1), "str", true, []byte{0xCA, 0xFE})
+		Array(buf.BinWriter, nil, int64(1), "str", true, []byte{0xCA, 0xFE})
 		require.NoError(t, buf.Err)
 
 		res := buf.Bytes()
@@ -154,6 +154,7 @@ func TestEmitArray(t *testing.T) {
 		assert.EqualValues(t, 3, res[6])
 		assert.EqualValues(t, []byte("str"), res[7:10])
 		assert.EqualValues(t, opcode.PUSH1, res[10])
+		assert.EqualValues(t, opcode.PUSHNULL, res[11])
 	})
 
 	t.Run("empty", func(t *testing.T) {