[NIT-3755] Serialization order of the chain config in the init message changes the genesis block hash

cmd/genesis-generator/genesis-generator.go

@@ -103,11 +103,11 @@ func mainImpl() error {
 		return fmt.Errorf("failed to generate genesis hash: %w", err)
 	}
 	// To get send root from genesis block, we need to deserialize the header extra information
-	gensisBlockHeader := genesisBlock.Header()
-	gensisBlockHeaderInfo := types.DeserializeHeaderExtraInformation(gensisBlockHeader)
+	genesisBlockHeader := genesisBlock.Header()
+	genesisBlockHeaderInfo := types.DeserializeHeaderExtraInformation(genesisBlockHeader)
 	globalState := validator.GoGlobalState{
 		BlockHash:  genesisBlock.Hash(),
-		SendRoot:   gensisBlockHeaderInfo.SendRoot,
+		SendRoot:   genesisBlockHeaderInfo.SendRoot,
 		Batch:      1,
 		PosInBatch: 0,
 	}
@@ -147,7 +147,7 @@ func extractSerializedChainConfigFromJSON(genesisJson []byte) ([]byte, error) {
 	// Decode with json.NewDecoder
 	decoder := json.NewDecoder(strings.NewReader(jsonStr))
 
-	// Set decoded json feilds to map
+	// Set decoded json fields to map
 	var result map[string]json.RawMessage
 	if err := decoder.Decode(&result); err != nil {
 		return nil, fmt.Errorf("failed to decode JSON: %w", err)

system_tests/genesis_block_test.go

@@ -0,0 +1,150 @@
+// Copyright 2025, Offchain Labs, Inc.
+// For license information, see https://github.com/OffchainLabs/nitro/blob/master/LICENSE.md
+
+package arbtest
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/big"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
+
+	"github.com/offchainlabs/nitro/arbos/arbosState"
+	"github.com/offchainlabs/nitro/arbos/arbostypes"
+	"github.com/offchainlabs/nitro/execution/gethexec"
+	"github.com/offchainlabs/nitro/statetransfer"
+)
+
+const chainId = 12345
+const chainOwner = "0x0000000000000000000000000000000000000000"
+
+func TestChainConfigSerializationOrderDoesNotChangeGenesisBlockHash(t *testing.T) {
+	serializedChainConfig1 := getChainConfig1(chainId)
+	serializedChainConfig2 := getChainConfig2(chainId)
+	validateSerializedConfigs(t, serializedChainConfig1, serializedChainConfig2)
+
+	genesisHash1 := computeGenesisBlockHash(t, serializedChainConfig1)
+	genesisHash2 := computeGenesisBlockHash(t, serializedChainConfig2)
+
+	require.Equal(t, genesisHash1, genesisHash2, "Genesis block hashes should be equal despite different serialization orders")
+}
+
+func validateSerializedConfigs(t *testing.T, serializedConfig1, serializedConfig2 []byte) {
+	// Sanity check to ensure that the two serializations are different
+	require.NotEqual(t, serializedConfig1, serializedConfig2)
+	// Sanity check to ensure that the two serializations encode the same object
+	var deserializedChainConfig1, deserializedChainConfig2 params.ChainConfig
+	err := json.Unmarshal(serializedConfig1, &deserializedChainConfig1)
+	require.NoError(t, err)
+	err = json.Unmarshal(serializedConfig2, &deserializedChainConfig2)
+	require.NoError(t, err)
+	require.Equal(t, deserializedChainConfig1, deserializedChainConfig2)
+}
+
+func getChainConfig1(chainId uint64) []byte {
+	return []byte(fmt.Sprintf(chainConfig1, chainId, chainOwner))
+}
+
+func getChainConfig2(chainId uint64) []byte {
+	return []byte(fmt.Sprintf(chainConfig2, chainId, chainOwner))
+}
+
+func computeGenesisBlockHash(t *testing.T, serializedChainConfig []byte) common.Hash {
+	var chainConfig params.ChainConfig
+	err := json.Unmarshal(serializedChainConfig, &chainConfig)
+	require.NoError(t, err)
+
+	parsedInitMessage := &arbostypes.ParsedInitMessage{
+		ChainId:               chainConfig.ChainID,
+		InitialL1BaseFee:      big.NewInt(1000000000),
+		ChainConfig:           &chainConfig,
+		SerializedChainConfig: serializedChainConfig,
+	}
+
+	genesisBlock := generateGenesisBlock(
+		t,
+		&chainConfig,
+		parsedInitMessage,
+	)
+	require.NoError(t, err)
+
+	return genesisBlock.Hash()
+}
+
+// Taken from cmd/genesis-generator/genesis-generator.go and adapted slightly
+func generateGenesisBlock(
+	t *testing.T,
+	chainConfig *params.ChainConfig,
+	initMessage *arbostypes.ParsedInitMessage,
+) *types.Block {
+	timestamp := uint64(0)
+	stateRoot, err := arbosState.InitializeArbosInDatabase(
+		rawdb.NewMemoryDatabase(),
+		gethexec.DefaultCacheConfigFor(&gethexec.DefaultCachingConfig),
+		statetransfer.NewMemoryInitDataReader(&statetransfer.ArbosInitializationInfo{
+			ChainOwner: common.HexToAddress(chainOwner),
+		}),
+		chainConfig,
+		&params.ArbOSInit{},
+		initMessage,
+		timestamp,
+		10,
+	)
+	require.NoError(t, err)
+
+	return arbosState.MakeGenesisBlock(common.Hash{}, 0, timestamp, stateRoot, chainConfig)
+}
+
+const chainConfig1 = `{
+  "chainId": %d,
+  "daoForkSupport": true,
+  "depositContractAddress": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+  "enableVerkleAtGenesis": false,
+  "ethash": {},
+  "clique": {
+	"period": 1,
+	"epoch": 1
+  },
+  "arbitrum": {	
+	"EnableArbOS": true,
+	"AllowDebugPrecompiles": true,
+	"DataAvailabilityCommittee": false,
+	"InitialArbOSVersion": 50,
+	"InitialChainOwner": "%s",
+	"GenesisBlockNum": 0,
+	"MaxCodeSize": 0,
+	"MaxInitCodeSize": 0
+  }
+}`
+
+// Changed order of fields:
+//   - daoForkSupport is now first, chainId is second
+//   - clique fields order changed
+const chainConfig2 = `{
+  "daoForkSupport": true,
+  "chainId": %d,
+  "depositContractAddress": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+  "enableVerkleAtGenesis": false,
+  "ethash": {},
+  "clique": {
+	"epoch": 1,
+	"period": 1
+  },
+  "arbitrum": {	
+	"EnableArbOS": true,
+	"AllowDebugPrecompiles": true,
+	"DataAvailabilityCommittee": false,
+	"InitialArbOSVersion": 50,
+	"InitialChainOwner": "%s",
+	"GenesisBlockNum": 0,
+	"MaxCodeSize": 0,
+	"MaxInitCodeSize": 0
+  }
+}`