From 16f952270c1e6426b7ddff2c440b1800e62b428f Mon Sep 17 00:00:00 2001
From: Anna Shaleva <shaleva.ann@nspcc.ru>
Date: Mon, 4 Apr 2022 16:43:15 +0300
Subject: [PATCH] core: add murmur32 to CryptoLib native contract

Close #2415.
---
 pkg/core/native/crypto.go           | 20 ++++++++++++++++++++
 pkg/core/native/crypto_test.go      | 21 +++++++++++++++++++++
 pkg/interop/native/crypto/crypto.go |  6 ++++++
 3 files changed, 47 insertions(+)

diff --git a/pkg/core/native/crypto.go b/pkg/core/native/crypto.go
index b377dd82e..0eb4d6add 100644
--- a/pkg/core/native/crypto.go
+++ b/pkg/core/native/crypto.go
@@ -2,6 +2,7 @@ package native
 
 import (
 	"crypto/elliptic"
+	"encoding/binary"
 	"errors"
 	"fmt"
 
@@ -14,6 +15,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+	"github.com/twmb/murmur3"
 )
 
 // Crypto represents CryptoLib contract.
@@ -46,6 +48,12 @@ func newCrypto() *Crypto {
 	md = newMethodAndPrice(c.ripemd160, 1<<15, callflag.NoneFlag)
 	c.AddMethod(md, desc)
 
+	desc = newDescriptor("murmur32", smartcontract.ByteArrayType,
+		manifest.NewParameter("data", smartcontract.ByteArrayType),
+		manifest.NewParameter("seed", smartcontract.IntegerType))
+	md = newMethodAndPrice(c.murmur32, 1<<13, callflag.NoneFlag)
+	c.AddMethod(md, desc)
+
 	desc = newDescriptor("verifyWithECDsa", smartcontract.BoolType,
 		manifest.NewParameter("message", smartcontract.ByteArrayType),
 		manifest.NewParameter("pubkey", smartcontract.ByteArrayType),
@@ -72,6 +80,18 @@ func (c *Crypto) ripemd160(_ *interop.Context, args []stackitem.Item) stackitem.
 	return stackitem.NewByteArray(hash.RipeMD160(bs).BytesBE())
 }
 
+func (c *Crypto) murmur32(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	bs, err := args[0].TryBytes()
+	if err != nil {
+		panic(err)
+	}
+	seed := toUint32(args[1])
+	h := murmur3.SeedSum32(seed, bs)
+	result := make([]byte, 4)
+	binary.LittleEndian.PutUint32(result, h)
+	return stackitem.NewByteArray(result)
+}
+
 func (c *Crypto) verifyWithECDsa(_ *interop.Context, args []stackitem.Item) stackitem.Item {
 	msg, err := args[0].TryBytes()
 	if err != nil {
diff --git a/pkg/core/native/crypto_test.go b/pkg/core/native/crypto_test.go
index 6c20854d2..727c160a9 100644
--- a/pkg/core/native/crypto_test.go
+++ b/pkg/core/native/crypto_test.go
@@ -1,6 +1,7 @@
 package native
 
 import (
+	"encoding/binary"
 	"encoding/hex"
 	"math"
 	"math/big"
@@ -43,6 +44,26 @@ func TestRIPEMD160(t *testing.T) {
 	})
 }
 
+func TestMurmur32(t *testing.T) {
+	c := newCrypto()
+	ic := &interop.Context{VM: vm.New()}
+
+	t.Run("bad arg type", func(t *testing.T) {
+		require.Panics(t, func() {
+			c.murmur32(ic, []stackitem.Item{stackitem.NewInterop(nil), stackitem.Make(5)})
+		})
+	})
+	t.Run("good", func(t *testing.T) {
+		// Example from the C# node:
+		// https://github.com/neo-project/neo/blob/2a64c1cc809d1ff4b3a573c7c22bffbbf69a738b/tests/neo.UnitTests/Cryptography/UT_Murmur32.cs#L18
+		data := []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1}
+		seed := 10
+		expected := make([]byte, 4)
+		binary.LittleEndian.PutUint32(expected, 378574820)
+		require.Equal(t, expected, c.murmur32(ic, []stackitem.Item{stackitem.NewByteArray(data), stackitem.Make(seed)}).Value().([]byte))
+	})
+}
+
 func TestCryptoLibVerifyWithECDsa(t *testing.T) {
 	t.Run("R1", func(t *testing.T) {
 		testECDSAVerify(t, Secp256r1)
diff --git a/pkg/interop/native/crypto/crypto.go b/pkg/interop/native/crypto/crypto.go
index 8bf8acf6c..8374cc26d 100644
--- a/pkg/interop/native/crypto/crypto.go
+++ b/pkg/interop/native/crypto/crypto.go
@@ -32,6 +32,12 @@ func Ripemd160(b []byte) interop.Hash160 {
 	return neogointernal.CallWithToken(Hash, "ripemd160", int(contract.NoneFlag), b).(interop.Hash160)
 }
 
+// Murmur32 calls `murmur32` method of native CryptoLib contract and computes Murmur32 hash of b
+// using the given seed.
+func Murmur32(b []byte, seed int) []byte {
+	return neogointernal.CallWithToken(Hash, "murmur32", int(contract.NoneFlag), b, seed).([]byte)
+}
+
 // VerifyWithECDsa calls `verifyWithECDsa` method of native CryptoLib contract and checks that sig is
 // correct msg's signature for a given pub (serialized public key on a given curve).
 func VerifyWithECDsa(msg []byte, pub interop.PublicKey, sig interop.Signature, curve NamedCurve) bool {