Implement PoW Chain Deposit Trie in Go (#1285)

beacon-chain/core/blocks/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
         "//beacon-chain/core/validators:go_default_library",
         "//beacon-chain/utils:go_default_library",
         "//proto/beacon/p2p/v1:go_default_library",
+        "//shared/bytes:go_default_library",
         "//shared/hashutil:go_default_library",
         "//shared/params:go_default_library",
         "//shared/slices:go_default_library",
@@ -39,6 +40,7 @@ go_test(
         "//shared/hashutil:go_default_library",
         "//shared/params:go_default_library",
         "//shared/ssz:go_default_library",
+        "//shared/trie:go_default_library",
         "@com_github_ethereum_go_ethereum//common:go_default_library",
         "@com_github_ethereum_go_ethereum//core/types:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",

beacon-chain/core/blocks/block_operations.go

@@ -12,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/state/stateutils"
 	v "github.com/prysmaticlabs/prysm/beacon-chain/core/validators"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
+	bytesutil "github.com/prysmaticlabs/prysm/shared/bytes"
 	"github.com/prysmaticlabs/prysm/shared/hashutil"
 	"github.com/prysmaticlabs/prysm/shared/params"
 	"github.com/prysmaticlabs/prysm/shared/slices"
@@ -589,16 +590,13 @@ func ProcessValidatorDeposits(
 }
 
 func verifyDeposit(beaconState *pb.BeaconState, deposit *pb.Deposit) error {
-	depositData := deposit.DepositData
 	// Verify Merkle proof of deposit and deposit trie root.
-	var receiptRoot [32]byte
-	var merkleLeaf [32]byte
-	copy(receiptRoot[:], beaconState.LatestDepositRootHash32)
-	copy(merkleLeaf[:], depositData)
+	receiptRoot := bytesutil.ToBytes32(beaconState.LatestDepositRootHash32)
 	if ok := trie.VerifyMerkleBranch(
-		merkleLeaf,
+		hashutil.Hash(deposit.DepositData),
 		deposit.MerkleBranchHash32S,
 		params.BeaconConfig().DepositContractTreeDepth,
+		deposit.MerkleTreeIndex,
 		receiptRoot,
 	); !ok {
 		return fmt.Errorf(

beacon-chain/core/blocks/block_operations_test.go

@@ -9,8 +9,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/prysmaticlabs/prysm/shared/trie"
+
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
-	"github.com/prysmaticlabs/prysm/shared/hashutil"
 	"github.com/prysmaticlabs/prysm/shared/params"
 	"github.com/prysmaticlabs/prysm/shared/ssz"
 )
@@ -1217,14 +1218,14 @@ func TestProcessValidatorDeposits_MerkleBranchFailsVerification(t *testing.T) {
 	data = append(data, timestamp...)
 
 	// We then create a merkle branch for the test.
-	branch := [][]byte{}
-	for i := uint64(0); i < params.BeaconConfig().DepositContractTreeDepth; i++ {
-		branch = append(branch, []byte{1})
-	}
+	depositTrie := trie.NewDepositTrie()
+	depositTrie.UpdateDepositTrie(data)
+	branch := depositTrie.GenerateMerkleBranch(0)
 
 	deposit := &pb.Deposit{
 		DepositData:         data,
 		MerkleBranchHash32S: branch,
+		MerkleTreeIndex:     0,
 	}
 	block := &pb.BeaconBlock{
 		Body: &pb.BeaconBlockBody{
@@ -1232,7 +1233,7 @@ func TestProcessValidatorDeposits_MerkleBranchFailsVerification(t *testing.T) {
 		},
 	}
 	beaconState := &pb.BeaconState{
-		LatestDepositRootHash32: []byte{0},
+		LatestDepositRootHash32: []byte{},
 	}
 	want := "merkle branch of deposit root did not verify"
 	if _, err := ProcessValidatorDeposits(
@@ -1283,22 +1284,15 @@ func TestProcessValidatorDeposits_ProcessDepositHelperFuncFails(t *testing.T) {
 	data = append(data, value...)
 	data = append(data, timestamp...)
 
-	// We then create a merkle branch for the test and derive its root.
-	branch := [][]byte{}
-	var powReceiptRoot [32]byte
-	copy(powReceiptRoot[:], data)
-	for i := uint64(0); i < params.BeaconConfig().DepositContractTreeDepth; i++ {
-		branch = append(branch, []byte{1})
-		if i%2 == 0 {
-			powReceiptRoot = hashutil.Hash(append(branch[i], powReceiptRoot[:]...))
-		} else {
-			powReceiptRoot = hashutil.Hash(append(powReceiptRoot[:], branch[i]...))
-		}
-	}
+	// We then create a merkle branch for the test.
+	depositTrie := trie.NewDepositTrie()
+	depositTrie.UpdateDepositTrie(data)
+	branch := depositTrie.GenerateMerkleBranch(0)
 
 	deposit := &pb.Deposit{
 		DepositData:         data,
 		MerkleBranchHash32S: branch,
+		MerkleTreeIndex:     0,
 	}
 	block := &pb.BeaconBlock{
 		Body: &pb.BeaconBlockBody{
@@ -1314,10 +1308,11 @@ func TestProcessValidatorDeposits_ProcessDepositHelperFuncFails(t *testing.T) {
 		},
 	}
 	balances := []uint64{0}
+	root := depositTrie.Root()
 	beaconState := &pb.BeaconState{
 		ValidatorRegistry:       registry,
 		ValidatorBalances:       balances,
-		LatestDepositRootHash32: powReceiptRoot[:],
+		LatestDepositRootHash32: root[:],
 		Slot:                    currentSlot,
 		GenesisTime:             uint64(genesisTime),
 	}
@@ -1368,22 +1363,15 @@ func TestProcessValidatorDeposits_ProcessCorrectly(t *testing.T) {
 	data = append(data, value...)
 	data = append(data, timestamp...)
 
-	// We then create a merkle branch for the test and derive its root.
-	branch := [][]byte{}
-	var powReceiptRoot [32]byte
-	copy(powReceiptRoot[:], data)
-	for i := uint64(0); i < params.BeaconConfig().DepositContractTreeDepth; i++ {
-		branch = append(branch, []byte{1})
-		if i%2 == 0 {
-			powReceiptRoot = hashutil.Hash(append(branch[i], powReceiptRoot[:]...))
-		} else {
-			powReceiptRoot = hashutil.Hash(append(powReceiptRoot[:], branch[i]...))
-		}
-	}
+	// We then create a merkle branch for the test.
+	depositTrie := trie.NewDepositTrie()
+	depositTrie.UpdateDepositTrie(data)
+	branch := depositTrie.GenerateMerkleBranch(0)
 
 	deposit := &pb.Deposit{
 		DepositData:         data,
 		MerkleBranchHash32S: branch,
+		MerkleTreeIndex:     0,
 	}
 	block := &pb.BeaconBlock{
 		Body: &pb.BeaconBlockBody{
@@ -1397,10 +1385,11 @@ func TestProcessValidatorDeposits_ProcessCorrectly(t *testing.T) {
 		},
 	}
 	balances := []uint64{0}
+	root := depositTrie.Root()
 	beaconState := &pb.BeaconState{
 		ValidatorRegistry:       registry,
 		ValidatorBalances:       balances,
-		LatestDepositRootHash32: powReceiptRoot[:],
+		LatestDepositRootHash32: root[:],
 		Slot:                    currentSlot,
 		GenesisTime:             uint64(genesisTime),
 	}

shared/p2p/service.go

@@ -240,14 +240,14 @@ func (s *Server) Send(msg proto.Message, peer Peer) {
 	s.Broadcast(msg)
 }
 
-// Broadcast publishes a message to all localized peers using gossipsub. 
-// msg must be a proto.Message that can be encoded into a byte array.  
-// It publishes the first 100 chars of msg over the msg's mapped topic. 
+// Broadcast publishes a message to all localized peers using gossipsub.
+// msg must be a proto.Message that can be encoded into a byte array.
+// It publishes the first 100 chars of msg over the msg's mapped topic.
 // To map a messageType to a topic, use RegisterTopic.
 //
-// It logs an error if msg is not a protobuf message, 
-// if msg cannot be encoded into a byte array, 
-// or if the server is unable to publish the message over gossipsub. 
+// It logs an error if msg is not a protobuf message,
+// if msg cannot be encoded into a byte array,
+// or if the server is unable to publish the message over gossipsub.
 //
 //   msg := make(chan p2p.Message, 100) // Choose a reasonable buffer size!
 //   ps.RegisterTopic("message_topic_here", msg)

shared/params/config.go

@@ -67,13 +67,12 @@ type BeaconChainConfig struct {
 	MaxCasperSlashings   uint64 // MaxCasperSlashings defines the maximum number of casper FFG slashings possible in a block.
 
 	// Prysm constants.
-	DepositsForChainStart      uint64    // DepositsForChainStart defines how many validator deposits needed to kick off beacon chain.
-	POWContractMerkleTreeDepth uint64    // POWContractMerkleTreeDepth defines the depth of PoW contract merkle tree.
-	SimulatedBlockRandao       [32]byte  // SimulatedBlockRandao is a RANDAO seed stubbed in simulated block for advancing local beacon chain.
-	RandBytes                  uint64    // RandBytes is the number of bytes used as entropy to shuffle validators.
-	SyncPollingInterval        int64     // SyncPollingInterval queries network nodes for sync status.
-	GenesisTime                time.Time // GenesisTime used by the protocol.
-	MaxNumLog2Validators       uint64    // MaxNumLog2Validators is the Max number of validators in Log2 exists given total ETH supply.
+	DepositsForChainStart uint64    // DepositsForChainStart defines how many validator deposits needed to kick off beacon chain.
+	SimulatedBlockRandao  [32]byte  // SimulatedBlockRandao is a RANDAO seed stubbed in simulated block for advancing local beacon chain.
+	RandBytes             uint64    // RandBytes is the number of bytes used as entropy to shuffle validators.
+	SyncPollingInterval   int64     // SyncPollingInterval queries network nodes for sync status.
+	GenesisTime           time.Time // GenesisTime used by the protocol.
+	MaxNumLog2Validators  uint64    // MaxNumLog2Validators is the Max number of validators in Log2 exists given total ETH supply.
 }
 
 // ShardChainConfig contains configs for node to participate in shard chains.

shared/trie/BUILD.bazel

@@ -2,15 +2,21 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
-    srcs = ["merkle.go"],
+    srcs = ["deposit_trie.go"],
     importpath = "github.com/prysmaticlabs/prysm/shared/trie",
     visibility = ["//visibility:public"],
-    deps = ["//shared/hashutil:go_default_library"],
+    deps = [
+        "//shared/hashutil:go_default_library",
+        "//shared/params:go_default_library",
+    ],
 )
 
 go_test(
     name = "go_default_test",
-    srcs = ["merkle_test.go"],
+    srcs = ["deposit_trie_test.go"],
     embed = [":go_default_library"],
-    deps = ["//shared/hashutil:go_default_library"],
+    deps = [
+        "//shared/hashutil:go_default_library",
+        "//shared/params:go_default_library",
+    ],
 )

shared/trie/deposit_trie.go

@@ -0,0 +1,81 @@
+// Package trie contains definitions for building a Merkle trie for validator deposits
+// as defined in the Ethereum Serenity specification, as well as utilities to generate
+// and verify Merkle proofs.
+package trie
+
+import (
+	"github.com/prysmaticlabs/prysm/shared/hashutil"
+	"github.com/prysmaticlabs/prysm/shared/params"
+)
+
+// DepositTrie represents a Merkle trie tracking deposits on the ETH 1.0
+// PoW chain contract created in Vyper.
+type DepositTrie struct {
+	depositCount uint64
+	merkleMap    map[uint64][32]byte
+}
+
+// NewDepositTrie creates a new struct instance representing a Merkle trie for deposits
+// and tracking an initial deposit count of 0.
+func NewDepositTrie() *DepositTrie {
+	return &DepositTrie{
+		depositCount: 0,
+		merkleMap:    make(map[uint64][32]byte),
+	}
+}
+
+// UpdateDepositTrie updates the Merkle trie representing deposits on
+// the ETH 1.0 PoW chain contract.
+func (d *DepositTrie) UpdateDepositTrie(depositData []byte) {
+	twoToPowerOfTreeDepth := 1 << params.BeaconConfig().DepositContractTreeDepth
+	index := d.depositCount + uint64(twoToPowerOfTreeDepth)
+	d.merkleMap[index] = hashutil.Hash(depositData)
+	for i := uint64(0); i < params.BeaconConfig().DepositContractTreeDepth; i++ {
+		index = index / 2
+		left := d.merkleMap[index*2]
+		right := d.merkleMap[index*2+1]
+		d.merkleMap[index] = hashutil.Hash(append(left[:], right[:]...))
+	}
+	d.depositCount++
+}
+
+// GenerateMerkleBranch for a value up to the root from a leaf in the trie.
+func (d *DepositTrie) GenerateMerkleBranch(index uint64) [][]byte {
+	twoToPowerOfTreeDepth := 1 << params.BeaconConfig().DepositContractTreeDepth
+	idx := index + uint64(twoToPowerOfTreeDepth)
+	branch := make([][]byte, params.BeaconConfig().DepositContractTreeDepth)
+	for i := uint64(0); i < params.BeaconConfig().DepositContractTreeDepth; i++ {
+		if idx%2 == 1 {
+			value := d.merkleMap[idx-1]
+			branch[i] = value[:]
+		} else {
+			value := d.merkleMap[idx+1]
+			branch[i] = value[:]
+		}
+		idx = idx / 2
+	}
+	return branch
+}
+
+// Root returns the Merkle root of the calculated deposit trie.
+func (d *DepositTrie) Root() [32]byte {
+	return d.merkleMap[1]
+}
+
+// VerifyMerkleBranch verifies a Merkle path in a trie
+// by checking the aggregated hash of contiguous leaves along a path
+// eventually equals the root hash of the Merkle trie.
+func VerifyMerkleBranch(leaf [32]byte, branch [][]byte, depth uint64, index uint64, root [32]byte) bool {
+	twoToPowerOfTreeDepth := 1 << params.BeaconConfig().DepositContractTreeDepth
+	idx := index + uint64(twoToPowerOfTreeDepth)
+	value := leaf
+	for i := uint64(0); i < depth; i++ {
+		if idx%2 == 1 {
+			value = hashutil.Hash(append(branch[i], value[:]...))
+		} else {
+			value = hashutil.Hash(append(value[:], branch[i]...))
+		}
+		idx = idx / 2
+	}
+	return value == root
+}

shared/trie/deposit_trie_test.go

@@ -0,0 +1,65 @@
+package trie
+
+import (
+	"testing"
+
+	"github.com/prysmaticlabs/prysm/shared/hashutil"
+	"github.com/prysmaticlabs/prysm/shared/params"
+)
+
+func TestDepositTrie_UpdateDepositTrie(t *testing.T) {
+	tests := []struct {
+		deposits [][]byte
+	}{
+		{
+			[][]byte{
+				{1, 2, 3, 4},
+				{5, 6, 7, 8},
+			},
+		},
+		{
+			[][]byte{
+				{0, 0, 0, 0},
+				{0, 0, 0, 0},
+			},
+		},
+	}
+	for _, tt := range tests {
+		d := NewDepositTrie()
+		d.UpdateDepositTrie(tt.deposits[0])
+		if d.depositCount != 1 {
+			t.Errorf("Expected deposit count to increase by 1, received %d", d.depositCount)
+		}
+		d.UpdateDepositTrie(tt.deposits[1])
+		if d.depositCount != 2 {
+			t.Errorf("Expected deposit count to increase by 1, received %d", d.depositCount)
+		}
+		hash := hashutil.Hash(tt.deposits[1])
+		twoToPowerOfTreeDepth := 1 << params.BeaconConfig().DepositContractTreeDepth
+		lastLeaf := d.merkleMap[d.depositCount-1+uint64(twoToPowerOfTreeDepth)]
+		if lastLeaf != hash {
+			t.Errorf("Expected last leaf to equal %#x, received %#x", lastLeaf, hash)
+		}
+	}
+}
+
+func TestDepositTrie_GenerateMerkleBranch(t *testing.T) {
+	d := NewDepositTrie()
+	deposit1 := []byte{1, 2, 3}
+	d.UpdateDepositTrie(deposit1)
+	deposit2 := []byte{5, 6, 7}
+	d.UpdateDepositTrie(deposit2)
+	deposit3 := []byte{8, 9, 10}
+	d.UpdateDepositTrie(deposit3)
+	index := d.depositCount - 1
+	branch := d.GenerateMerkleBranch(index)
+	if ok := VerifyMerkleBranch(
+		hashutil.Hash(deposit3),
+		branch,
+		params.BeaconConfig().DepositContractTreeDepth,
+		index,
+		d.Root(),
+	); !ok {
+		t.Error("Expected Merkle branch to verify, received false")
+	}
+}

shared/trie/merkle.go

@@ -1,20 +0,0 @@
-package trie
-
-import (
-	"github.com/prysmaticlabs/prysm/shared/hashutil"
-)
-
-// VerifyMerkleBranch verifies a merkle path in a trie
-// by checking the aggregated hash of contiguous leaves along a path
-// eventually equals the root hash of the merkle trie.
-func VerifyMerkleBranch(leaf [32]byte, branch [][]byte, depth uint64, root [32]byte) bool {
-	value := leaf
-	for i := uint64(0); i < depth; i++ {
-		if i%2 == 0 {
-			value = hashutil.Hash(append(branch[i], value[:]...))
-		} else {
-			value = hashutil.Hash(append(value[:], branch[i]...))
-		}
-	}
-	return value == root
-}

shared/trie/merkle_test.go

@@ -1,32 +0,0 @@
-package trie
-
-import (
-	"testing"
-
-	"github.com/prysmaticlabs/prysm/shared/hashutil"
-)
-
-func TestVerifyMerkleBranch(t *testing.T) {
-	// We build up a Merkle proof and then run
-	// the verify function for data integrity testing
-	// along a Merkle branch in a Merkle trie structure.
-	depth := 4
-	leaf := [32]byte{1, 2, 3}
-	root := leaf
-	branch := [][]byte{
-		{4, 5, 6},
-		{7, 8, 9},
-		{10, 11, 12},
-		{13, 14, 15},
-	}
-	for i := 0; i < depth; i++ {
-		if i%2 == 0 {
-			root = hashutil.Hash(append(branch[i], root[:]...))
-		} else {
-			root = hashutil.Hash(append(root[:], branch[i]...))
-		}
-	}
-	if ok := VerifyMerkleBranch(leaf, branch, uint64(depth), root); !ok {
-		t.Error("Expected merkle branch to verify, received false")
-	}
-}