Test

rvgo/evm_test.go

@@ -149,13 +149,13 @@ func stepEVM(t *testing.T, env *vm.EVM, wit *fast.StepWitness, addrs *Addresses,
 	snap := env.StateDB.Snapshot()
 
 	if wit.HasPreimage() {
-		input, err := wit.EncodePreimageOracleInput()
+		input, err := wit.EncodePreimageOracleInput(fast.LocalContext{})
 		require.NoError(t, err)
 		ret, leftOverGas, err := env.Call(vm.AccountRef(addrs.Sender), addrs.Oracle, input, startingGas, big.NewInt(0))
 		require.NoError(t, err, "evm must not fail (ret: %x, gas: %d)", ret, startingGas-leftOverGas)
 	}
 
-	input := wit.EncodeStepInput()
+	input := wit.EncodeStepInput(fast.LocalContext{})
 
 	ret, leftOverGas, err := env.Call(vm.AccountRef(addrs.Sender), addrs.RISCV, input, startingGas, big.NewInt(0))
 	require.NoError(t, err, "evm must not fail (ret: %x), at step %d", ret, step)

rvgo/fast/evm.go

@@ -5,5 +5,6 @@ import "github.com/ethereum/go-ethereum/crypto"
 var (
 	StepBytes4                      = crypto.Keccak256([]byte("step(bytes,bytes,bytes32)"))[:4]
 	CheatBytes4                     = crypto.Keccak256([]byte("cheat(uint256,bytes32,bytes32,uint256)"))[:4]
+	CheatLocalKeyBytes4             = crypto.Keccak256([]byte("cheatLocalKey(uint256,bytes32,bytes32,uint256,bytes32)"))[:4]
 	LoadKeccak256PreimagePartBytes4 = crypto.Keccak256([]byte("loadKeccak256PreimagePart(uint256,bytes)"))[:4]
 )

rvgo/fast/witness.go

@@ -6,8 +6,11 @@ import (
 	"fmt"
 
 	preimage "github.com/ethereum-optimism/optimism/op-preimage"
+	"github.com/ethereum/go-ethereum/common"
 )
 
+type LocalContext common.Hash
+
 type StepWitness struct {
 	// encoded state witness
 	State []byte
@@ -25,7 +28,7 @@ func uint64ToBytes32(v uint64) []byte {
 	return out[:]
 }
 
-func (wit *StepWitness) EncodeStepInput() []byte {
+func (wit *StepWitness) EncodeStepInput(localContext LocalContext) []byte {
 	abiStatePadding := (32 - (uint64(len(wit.State)) % 32)) % 32
 	abiProofPadding := (32 - (uint64(len(wit.MemProof)) % 32)) % 32
 
@@ -35,8 +38,8 @@ func (wit *StepWitness) EncodeStepInput() []byte {
 	input = append(input, uint64ToBytes32(32*3)...)
 	// proof data offset in bytes
 	input = append(input, uint64ToBytes32(32*3+32+uint64(len(wit.State))+abiStatePadding)...)
-	// dummy localContext
-	input = append(input, make([]byte, 32)...)
+	// local context in bytes
+	input = append(input, common.Hash(localContext).Bytes()...)
 
 	// state data length in bytes
 	input = append(input, uint64ToBytes32(uint64(len(wit.State)))...)
@@ -53,7 +56,7 @@ func (wit *StepWitness) HasPreimage() bool {
 	return wit.PreimageKey != ([32]byte{})
 }
 
-func (wit *StepWitness) EncodePreimageOracleInput() ([]byte, error) {
+func (wit *StepWitness) EncodePreimageOracleInput(localContext LocalContext) ([]byte, error) {
 	if wit.PreimageKey == ([32]byte{}) {
 		return nil, errors.New("cannot encode pre-image oracle input, witness has no pre-image to proof")
 	}
@@ -65,13 +68,14 @@ func (wit *StepWitness) EncodePreimageOracleInput() ([]byte, error) {
 		// In production usage there should be an on-chain contract that exposes this,
 		// rather than going through the global keccak256 oracle.
 		var input []byte
-		input = append(input, CheatBytes4...)
+		input = append(input, CheatLocalKeyBytes4...)
 		input = append(input, uint64ToBytes32(wit.PreimageOffset)...)
 		input = append(input, wit.PreimageKey[:]...)
 		var tmp [32]byte
 		copy(tmp[:], wit.PreimageValue[wit.PreimageOffset:])
 		input = append(input, tmp[:]...)
 		input = append(input, uint64ToBytes32(uint64(len(wit.PreimageValue))-8)...)
+		input = append(input, common.Hash(localContext).Bytes()...)
 		// Note: we can pad calldata to 32 byte multiple, but don't strictly have to
 		return input, nil
 	case preimage.Keccak256KeyType:

rvgo/vm_go_test.go

@@ -111,7 +111,7 @@ func fullTest(t *testing.T, vmState *fast.VMState, po *testOracle, symbols fast.
 			require.NoError(t, err)
 
 			if runSlow {
-				slowPostHash, err := slow.Step(wit.EncodeStepInput(), po)
+				slowPostHash, err := slow.Step(wit.EncodeStepInput(fast.LocalContext{}), po)
 				require.NoErrorf(t, err, "slow VM err at step %d, PC %08x: %v", i, vmState.PC, err)
 				require.Equal(t, fastStateHash, slowPostHash, "fast post-state must match slow post-state")
 			}

rvgo/vm_test.go

@@ -75,7 +75,7 @@ func runSlowTestSuite(t *testing.T, path string) {
 		require.NoError(t, err)
 
 		// Now run the same in slow mode
-		input := wit.EncodeStepInput()
+		input := wit.EncodeStepInput(fast.LocalContext{})
 		post, err := slow.Step(input, nil)
 		require.NoErrorf(t, err, "slow VM err at step %d, PC %08x: %v", i, vmState.PC, err)
 

rvsol/src/PreimageOracle.sol

@@ -32,6 +32,32 @@ contract PreimageOracle {
         preimageLengths[key] = size;
     }
 
+    function localize(bytes32 _key, bytes32 _localContext) internal view returns (bytes32 localizedKey_) {
+        assembly {
+            // Grab the current free memory pointer to restore later.
+            let ptr := mload(0x40)
+            // Store the local data key and caller next to each other in memory for hashing.
+            mstore(0, _key)
+            mstore(0x20, caller())
+            mstore(0x40, _localContext)
+            // Localize the key with the above `localize` operation.
+            localizedKey_ := or(and(keccak256(0, 0x60), not(shl(248, 0xFF))), shl(248, 1))
+            // Restore the free memory pointer.
+            mstore(0x40, ptr)
+        }
+    }
+
+    // temporary method for localizeation
+    function cheatLocalKey(uint256 partOffset, bytes32 key, bytes32 part, uint256 size, bytes32 localContext) external {
+        // sanity check key is local key using prefix
+        require(uint8(key[0]) == 1, "must be used for local key");
+
+        bytes32 localizedKey = localize(key, localContext);
+        preimagePartOk[localizedKey][partOffset] = true;
+        preimageParts[localizedKey][partOffset] = part;
+        preimageLengths[localizedKey] = size;
+    }
+
     // loadKeccak256PreimagePart prepares the pre-image to be read by keccak256 key,
     // starting at the given offset, up to 32 bytes (clipped at preimage length, if out of data).
     function loadKeccak256PreimagePart(uint256 _partOffset, bytes calldata _preimage) external {