diff --git a/accounts/abi/bind/backends/simulated.go b/accounts/abi/bind/backends/simulated.go
index 7bff1a125..c26662ea1 100644
--- a/accounts/abi/bind/backends/simulated.go
+++ b/accounts/abi/bind/backends/simulated.go
@@ -61,7 +61,7 @@ type SimulatedBackend struct {
 func NewSimulatedBackend(accounts ...core.GenesisAccount) *SimulatedBackend {
 	database, _ := ethdb.NewMemDatabase()
 	core.WriteGenesisBlockForTesting(database, accounts...)
-	blockchain, _ := core.NewBlockChain(database, chainConfig, new(core.FakePow), new(event.TypeMux))
+	blockchain, _ := core.NewBlockChain(database, chainConfig, new(core.FakePow), new(event.TypeMux), vm.Config{})
 	backend := &SimulatedBackend{database: database, blockchain: blockchain}
 	backend.rollback()
 	return backend
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index a6b6331df..ac34d3035 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -132,6 +132,7 @@ func init() {
 		utils.VMForceJitFlag,
 		utils.VMJitCacheFlag,
 		utils.VMEnableJitFlag,
+		utils.VMEnableDebugFlag,
 		utils.NetworkIdFlag,
 		utils.RPCCORSDomainFlag,
 		utils.EthStatsURLFlag,
diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
index 853307604..5ebfc8919 100644
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@@ -155,6 +155,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.VMEnableJitFlag,
 			utils.VMForceJitFlag,
 			utils.VMJitCacheFlag,
+			utils.VMEnableDebugFlag,
 		},
 	},
 	{
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 01114a957..08b4db578 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -33,6 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -230,6 +231,10 @@ var (
 		Name:  "jitvm",
 		Usage: "Enable the JIT VM",
 	}
+	VMEnableDebugFlag = cli.BoolFlag{
+		Name:  "vmdebug",
+		Usage: "Record information useful for VM and contract debugging",
+	}
 	// Logging and debug settings
 	EthStatsURLFlag = cli.StringFlag{
 		Name:  "ethstats",
@@ -741,6 +746,7 @@ func RegisterEthService(ctx *cli.Context, stack *node.Node, extra []byte) {
 		GpobaseCorrectionFactor: ctx.GlobalInt(GpobaseCorrectionFactorFlag.Name),
 		SolcPath:                ctx.GlobalString(SolcPathFlag.Name),
 		AutoDAG:                 ctx.GlobalBool(AutoDAGFlag.Name) || ctx.GlobalBool(MiningEnabledFlag.Name),
+		EnablePreimageRecording: ctx.GlobalBool(VMEnableDebugFlag.Name),
 	}
 
 	// Override any default configs in dev mode or the test net
@@ -912,7 +918,7 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 	if !ctx.GlobalBool(FakePoWFlag.Name) {
 		pow = ethash.New()
 	}
-	chain, err = core.NewBlockChain(chainDb, chainConfig, pow, new(event.TypeMux))
+	chain, err = core.NewBlockChain(chainDb, chainConfig, pow, new(event.TypeMux), vm.Config{EnablePreimageRecording: ctx.GlobalBool(VMEnableDebugFlag.Name)})
 	if err != nil {
 		Fatalf("Could not start chainmanager: %v", err)
 	}
diff --git a/core/bench_test.go b/core/bench_test.go
index 5785748a1..353d217fd 100644
--- a/core/bench_test.go
+++ b/core/bench_test.go
@@ -25,6 +25,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -168,7 +169,7 @@ func benchInsertChain(b *testing.B, disk bool, gen func(int, *BlockGen)) {
 	// Time the insertion of the new chain.
 	// State and blocks are stored in the same DB.
 	evmux := new(event.TypeMux)
-	chainman, _ := NewBlockChain(db, &params.ChainConfig{HomesteadBlock: new(big.Int)}, FakePow{}, evmux)
+	chainman, _ := NewBlockChain(db, &params.ChainConfig{HomesteadBlock: new(big.Int)}, FakePow{}, evmux, vm.Config{})
 	defer chainman.Stop()
 	b.ReportAllocs()
 	b.ResetTimer()
@@ -278,7 +279,7 @@ func benchReadChain(b *testing.B, full bool, count uint64) {
 		if err != nil {
 			b.Fatalf("error opening database at %v: %v", dir, err)
 		}
-		chain, err := NewBlockChain(db, testChainConfig(), FakePow{}, new(event.TypeMux))
+		chain, err := NewBlockChain(db, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 		if err != nil {
 			b.Fatalf("error creating chain: %v", err)
 		}
diff --git a/core/block_validator_test.go b/core/block_validator_test.go
index 413c3cc8e..01931efd2 100644
--- a/core/block_validator_test.go
+++ b/core/block_validator_test.go
@@ -24,6 +24,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
@@ -39,7 +40,7 @@ func proc() (Validator, *BlockChain) {
 	var mux event.TypeMux
 
 	WriteTestNetGenesisBlock(db)
-	blockchain, err := NewBlockChain(db, testChainConfig(), thePow(), &mux)
+	blockchain, err := NewBlockChain(db, testChainConfig(), thePow(), &mux, vm.Config{})
 	if err != nil {
 		fmt.Println(err)
 	}
diff --git a/core/blockchain.go b/core/blockchain.go
index 6462c17fa..2e522d97c 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -107,12 +107,13 @@ type BlockChain struct {
 	pow       pow.PoW
 	processor Processor // block processor interface
 	validator Validator // block and state validator interface
+	vmConfig  vm.Config
 }
 
 // NewBlockChain returns a fully initialised block chain using information
 // available in the database. It initialiser the default Ethereum Validator and
 // Processor.
-func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, pow pow.PoW, mux *event.TypeMux) (*BlockChain, error) {
+func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, pow pow.PoW, mux *event.TypeMux, vmConfig vm.Config) (*BlockChain, error) {
 	bodyCache, _ := lru.New(bodyCacheLimit)
 	bodyRLPCache, _ := lru.New(bodyCacheLimit)
 	blockCache, _ := lru.New(blockCacheLimit)
@@ -128,6 +129,7 @@ func NewBlockChain(chainDb ethdb.Database, config *params.ChainConfig, pow pow.P
 		blockCache:   blockCache,
 		futureBlocks: futureBlocks,
 		pow:          pow,
+		vmConfig:     vmConfig,
 	}
 	bc.SetValidator(NewBlockValidator(config, bc, pow))
 	bc.SetProcessor(NewStateProcessor(config, bc))
@@ -954,7 +956,7 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			return i, err
 		}
 		// Process block using the parent state as reference point.
-		receipts, logs, usedGas, err := self.processor.Process(block, self.stateCache, vm.Config{})
+		receipts, logs, usedGas, err := self.processor.Process(block, self.stateCache, self.vmConfig)
 		if err != nil {
 			self.reportBlock(block, receipts, err)
 			return i, err
@@ -1004,6 +1006,10 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			if err := WriteMipmapBloom(self.chainDb, block.NumberU64(), receipts); err != nil {
 				return i, err
 			}
+			// Write hash preimages
+			if err := WritePreimages(self.chainDb, block.NumberU64(), self.stateCache.Preimages()); err != nil {
+				return i, err
+			}
 		case SideStatTy:
 			if glog.V(logger.Detail) {
 				glog.Infof("inserted forked block #%d [%x…] (TD=%v) in %9v: %3d txs %d uncles.", block.Number(), block.Hash().Bytes()[0:4], block.Difficulty(), common.PrettyDuration(time.Since(bstart)), len(block.Transactions()), len(block.Uncles()))
diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index a5a83ba60..8f1383acd 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -53,7 +53,7 @@ func thePow() pow.PoW {
 func theBlockChain(db ethdb.Database, t *testing.T) *BlockChain {
 	var eventMux event.TypeMux
 	WriteTestNetGenesisBlock(db)
-	blockchain, err := NewBlockChain(db, testChainConfig(), thePow(), &eventMux)
+	blockchain, err := NewBlockChain(db, testChainConfig(), thePow(), &eventMux, vm.Config{})
 	if err != nil {
 		t.Error("failed creating blockchain:", err)
 		t.FailNow()
@@ -614,7 +614,7 @@ func testReorgBadHashes(t *testing.T, full bool) {
 		defer func() { delete(BadHashes, headers[3].Hash()) }()
 	}
 	// Create a new chain manager and check it rolled back the state
-	ncm, err := NewBlockChain(db, testChainConfig(), FakePow{}, new(event.TypeMux))
+	ncm, err := NewBlockChain(db, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 	if err != nil {
 		t.Fatalf("failed to create new chain manager: %v", err)
 	}
@@ -735,7 +735,7 @@ func TestFastVsFullChains(t *testing.T) {
 	archiveDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(archiveDb, GenesisAccount{address, funds})
 
-	archive, _ := NewBlockChain(archiveDb, testChainConfig(), FakePow{}, new(event.TypeMux))
+	archive, _ := NewBlockChain(archiveDb, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 
 	if n, err := archive.InsertChain(blocks); err != nil {
 		t.Fatalf("failed to process block %d: %v", n, err)
@@ -743,7 +743,7 @@ func TestFastVsFullChains(t *testing.T) {
 	// Fast import the chain as a non-archive node to test
 	fastDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(fastDb, GenesisAccount{address, funds})
-	fast, _ := NewBlockChain(fastDb, testChainConfig(), FakePow{}, new(event.TypeMux))
+	fast, _ := NewBlockChain(fastDb, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 
 	headers := make([]*types.Header, len(blocks))
 	for i, block := range blocks {
@@ -819,7 +819,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	archiveDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(archiveDb, GenesisAccount{address, funds})
 
-	archive, _ := NewBlockChain(archiveDb, testChainConfig(), FakePow{}, new(event.TypeMux))
+	archive, _ := NewBlockChain(archiveDb, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 
 	if n, err := archive.InsertChain(blocks); err != nil {
 		t.Fatalf("failed to process block %d: %v", n, err)
@@ -831,7 +831,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	// Import the chain as a non-archive node and ensure all pointers are updated
 	fastDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(fastDb, GenesisAccount{address, funds})
-	fast, _ := NewBlockChain(fastDb, testChainConfig(), FakePow{}, new(event.TypeMux))
+	fast, _ := NewBlockChain(fastDb, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 
 	headers := make([]*types.Header, len(blocks))
 	for i, block := range blocks {
@@ -850,7 +850,7 @@ func TestLightVsFastVsFullChainHeads(t *testing.T) {
 	// Import the chain as a light node and ensure all pointers are updated
 	lightDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(lightDb, GenesisAccount{address, funds})
-	light, _ := NewBlockChain(lightDb, testChainConfig(), FakePow{}, new(event.TypeMux))
+	light, _ := NewBlockChain(lightDb, testChainConfig(), FakePow{}, new(event.TypeMux), vm.Config{})
 
 	if n, err := light.InsertHeaderChain(headers, 1); err != nil {
 		t.Fatalf("failed to insert header %d: %v", n, err)
@@ -916,7 +916,7 @@ func TestChainTxReorgs(t *testing.T) {
 	})
 	// Import the chain. This runs all block validation rules.
 	evmux := &event.TypeMux{}
-	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux, vm.Config{})
 	if i, err := blockchain.InsertChain(chain); err != nil {
 		t.Fatalf("failed to insert original chain[%d]: %v", i, err)
 	}
@@ -990,7 +990,7 @@ func TestLogReorgs(t *testing.T) {
 	)
 
 	evmux := &event.TypeMux{}
-	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux, vm.Config{})
 
 	subs := evmux.Subscribe(RemovedLogsEvent{})
 	chain, _ := GenerateChain(params.TestChainConfig, genesis, db, 2, func(i int, gen *BlockGen) {
@@ -1027,7 +1027,7 @@ func TestReorgSideEvent(t *testing.T) {
 	)
 
 	evmux := &event.TypeMux{}
-	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux, vm.Config{})
 
 	chain, _ := GenerateChain(params.TestChainConfig, genesis, db, 3, func(i int, gen *BlockGen) {})
 	if _, err := blockchain.InsertChain(chain); err != nil {
@@ -1103,7 +1103,7 @@ func TestCanonicalBlockRetrieval(t *testing.T) {
 	)
 
 	evmux := &event.TypeMux{}
-	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, testChainConfig(), FakePow{}, evmux, vm.Config{})
 
 	chain, _ := GenerateChain(params.TestChainConfig, genesis, db, 10, func(i int, gen *BlockGen) {})
 
@@ -1146,7 +1146,7 @@ func TestEIP155Transition(t *testing.T) {
 		mux        event.TypeMux
 	)
 
-	blockchain, _ := NewBlockChain(db, config, FakePow{}, &mux)
+	blockchain, _ := NewBlockChain(db, config, FakePow{}, &mux, vm.Config{})
 	blocks, _ := GenerateChain(config, genesis, db, 4, func(i int, block *BlockGen) {
 		var (
 			tx      *types.Transaction
@@ -1250,7 +1250,7 @@ func TestEIP161AccountRemoval(t *testing.T) {
 		}
 		mux event.TypeMux
 
-		blockchain, _ = NewBlockChain(db, config, FakePow{}, &mux)
+		blockchain, _ = NewBlockChain(db, config, FakePow{}, &mux, vm.Config{})
 	)
 	blocks, _ := GenerateChain(config, genesis, db, 3, func(i int, block *BlockGen) {
 		var (
diff --git a/core/chain_makers.go b/core/chain_makers.go
index 4a838a5aa..8b3b015a8 100644
--- a/core/chain_makers.go
+++ b/core/chain_makers.go
@@ -256,7 +256,7 @@ func newCanonical(n int, full bool) (ethdb.Database, *BlockChain, error) {
 	// Initialize a fresh chain with only a genesis block
 	genesis, _ := WriteTestNetGenesisBlock(db)
 
-	blockchain, _ := NewBlockChain(db, MakeChainConfig(), FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, MakeChainConfig(), FakePow{}, evmux, vm.Config{})
 	// Create and inject the requested chain
 	if n == 0 {
 		return db, blockchain, nil
diff --git a/core/chain_makers_test.go b/core/chain_makers_test.go
index 942f4ace2..2796817c0 100644
--- a/core/chain_makers_test.go
+++ b/core/chain_makers_test.go
@@ -21,6 +21,7 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -81,7 +82,7 @@ func ExampleGenerateChain() {
 
 	// Import the chain. This runs all block validation rules.
 	evmux := &event.TypeMux{}
-	blockchain, _ := NewBlockChain(db, chainConfig, FakePow{}, evmux)
+	blockchain, _ := NewBlockChain(db, chainConfig, FakePow{}, evmux, vm.Config{})
 	if i, err := blockchain.InsertChain(chain); err != nil {
 		fmt.Printf("insert error (block %d): %v\n", chain[i].NumberU64(), err)
 		return
diff --git a/core/dao_test.go b/core/dao_test.go
index f461131f4..b8b4c71cf 100644
--- a/core/dao_test.go
+++ b/core/dao_test.go
@@ -20,6 +20,7 @@ import (
 	"math/big"
 	"testing"
 
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
@@ -39,12 +40,12 @@ func TestDAOForkRangeExtradata(t *testing.T) {
 	proDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(proDb)
 	proConf := &params.ChainConfig{HomesteadBlock: big.NewInt(0), DAOForkBlock: forkBlock, DAOForkSupport: true}
-	proBc, _ := NewBlockChain(proDb, proConf, new(FakePow), new(event.TypeMux))
+	proBc, _ := NewBlockChain(proDb, proConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 	conDb, _ := ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(conDb)
 	conConf := &params.ChainConfig{HomesteadBlock: big.NewInt(0), DAOForkBlock: forkBlock, DAOForkSupport: false}
-	conBc, _ := NewBlockChain(conDb, conConf, new(FakePow), new(event.TypeMux))
+	conBc, _ := NewBlockChain(conDb, conConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 	if _, err := proBc.InsertChain(prefix); err != nil {
 		t.Fatalf("pro-fork: failed to import chain prefix: %v", err)
@@ -57,7 +58,7 @@ func TestDAOForkRangeExtradata(t *testing.T) {
 		// Create a pro-fork block, and try to feed into the no-fork chain
 		db, _ = ethdb.NewMemDatabase()
 		WriteGenesisBlockForTesting(db)
-		bc, _ := NewBlockChain(db, conConf, new(FakePow), new(event.TypeMux))
+		bc, _ := NewBlockChain(db, conConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 		blocks := conBc.GetBlocksFromHash(conBc.CurrentBlock().Hash(), int(conBc.CurrentBlock().NumberU64()+1))
 		for j := 0; j < len(blocks)/2; j++ {
@@ -78,7 +79,7 @@ func TestDAOForkRangeExtradata(t *testing.T) {
 		// Create a no-fork block, and try to feed into the pro-fork chain
 		db, _ = ethdb.NewMemDatabase()
 		WriteGenesisBlockForTesting(db)
-		bc, _ = NewBlockChain(db, proConf, new(FakePow), new(event.TypeMux))
+		bc, _ = NewBlockChain(db, proConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 		blocks = proBc.GetBlocksFromHash(proBc.CurrentBlock().Hash(), int(proBc.CurrentBlock().NumberU64()+1))
 		for j := 0; j < len(blocks)/2; j++ {
@@ -100,7 +101,7 @@ func TestDAOForkRangeExtradata(t *testing.T) {
 	// Verify that contra-forkers accept pro-fork extra-datas after forking finishes
 	db, _ = ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(db)
-	bc, _ := NewBlockChain(db, conConf, new(FakePow), new(event.TypeMux))
+	bc, _ := NewBlockChain(db, conConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 	blocks := conBc.GetBlocksFromHash(conBc.CurrentBlock().Hash(), int(conBc.CurrentBlock().NumberU64()+1))
 	for j := 0; j < len(blocks)/2; j++ {
@@ -116,7 +117,7 @@ func TestDAOForkRangeExtradata(t *testing.T) {
 	// Verify that pro-forkers accept contra-fork extra-datas after forking finishes
 	db, _ = ethdb.NewMemDatabase()
 	WriteGenesisBlockForTesting(db)
-	bc, _ = NewBlockChain(db, proConf, new(FakePow), new(event.TypeMux))
+	bc, _ = NewBlockChain(db, proConf, new(FakePow), new(event.TypeMux), vm.Config{})
 
 	blocks = proBc.GetBlocksFromHash(proBc.CurrentBlock().Hash(), int(proBc.CurrentBlock().NumberU64()+1))
 	for j := 0; j < len(blocks)/2; j++ {
diff --git a/core/database_util.go b/core/database_util.go
index 2060b8b6a..229f21b5b 100644
--- a/core/database_util.go
+++ b/core/database_util.go
@@ -30,6 +30,7 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -39,12 +40,13 @@ var (
 	headBlockKey  = []byte("LastBlock")
 	headFastKey   = []byte("LastFast")
 
-	headerPrefix        = []byte("h") // headerPrefix + num (uint64 big endian) + hash -> header
-	tdSuffix            = []byte("t") // headerPrefix + num (uint64 big endian) + hash + tdSuffix -> td
-	numSuffix           = []byte("n") // headerPrefix + num (uint64 big endian) + numSuffix -> hash
-	blockHashPrefix     = []byte("H") // blockHashPrefix + hash -> num (uint64 big endian)
-	bodyPrefix          = []byte("b") // bodyPrefix + num (uint64 big endian) + hash -> block body
-	blockReceiptsPrefix = []byte("r") // blockReceiptsPrefix + num (uint64 big endian) + hash -> block receipts
+	headerPrefix        = []byte("h")   // headerPrefix + num (uint64 big endian) + hash -> header
+	tdSuffix            = []byte("t")   // headerPrefix + num (uint64 big endian) + hash + tdSuffix -> td
+	numSuffix           = []byte("n")   // headerPrefix + num (uint64 big endian) + numSuffix -> hash
+	blockHashPrefix     = []byte("H")   // blockHashPrefix + hash -> num (uint64 big endian)
+	bodyPrefix          = []byte("b")   // bodyPrefix + num (uint64 big endian) + hash -> block body
+	blockReceiptsPrefix = []byte("r")   // blockReceiptsPrefix + num (uint64 big endian) + hash -> block receipts
+	preimagePrefix      = "secure-key-" // preimagePrefix + hash -> preimage
 
 	txMetaSuffix   = []byte{0x01}
 	receiptsPrefix = []byte("receipts-")
@@ -66,6 +68,9 @@ var (
 	ChainConfigNotFoundErr = errors.New("ChainConfig not found") // general config not found error
 
 	mipmapBloomMu sync.Mutex // protect against race condition when updating mipmap blooms
+
+	preimageCounter    = metrics.NewCounter("db/preimage/total")
+	preimageHitCounter = metrics.NewCounter("db/preimage/hits")
 )
 
 // encodeBlockNumber encodes a block number as big endian uint64
@@ -595,6 +600,34 @@ func GetMipmapBloom(db ethdb.Database, number, level uint64) types.Bloom {
 	return types.BytesToBloom(bloomDat)
 }
 
+// PreimageTable returns a Database instance with the key prefix for preimage entries.
+func PreimageTable(db ethdb.Database) ethdb.Database {
+	return ethdb.NewTable(db, preimagePrefix)
+}
+
+// WritePreimages writes the provided set of preimages to the database. `number` is the
+// current block number, and is used for debug messages only.
+func WritePreimages(db ethdb.Database, number uint64, preimages map[common.Hash][]byte) error {
+	table := PreimageTable(db)
+	batch := table.NewBatch()
+	hitCount := 0
+	for hash, preimage := range preimages {
+		if _, err := table.Get(hash.Bytes()); err != nil {
+			batch.Put(hash.Bytes(), preimage)
+			hitCount += 1
+		}
+	}
+	preimageCounter.Inc(int64(len(preimages)))
+	preimageHitCounter.Inc(int64(hitCount))
+	if hitCount > 0 {
+		if err := batch.Write(); err != nil {
+			return fmt.Errorf("preimage write fail for block %d: %v", number, err)
+		}
+		glog.V(logger.Debug).Infof("%d preimages in block %d, including %d new", len(preimages), number, hitCount)
+	}
+	return nil
+}
+
 // GetBlockChainVersion reads the version number from db.
 func GetBlockChainVersion(db ethdb.Database) int {
 	var vsn uint
diff --git a/core/state/journal.go b/core/state/journal.go
index d1e73e7d0..68d07fa03 100644
--- a/core/state/journal.go
+++ b/core/state/journal.go
@@ -67,6 +67,9 @@ type (
 	addLogChange struct {
 		txhash common.Hash
 	}
+	addPreimageChange struct {
+		hash common.Hash
+	}
 	touchChange struct {
 		account *common.Address
 		prev    bool
@@ -127,3 +130,7 @@ func (ch addLogChange) undo(s *StateDB) {
 		s.logs[ch.txhash] = logs[:len(logs)-1]
 	}
 }
+
+func (ch addPreimageChange) undo(s *StateDB) {
+	delete(s.preimages, ch.hash)
+}
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 063e2b469..bbccba9fb 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -75,6 +75,8 @@ type StateDB struct {
 	logs         map[common.Hash][]*types.Log
 	logSize      uint
 
+	preimages map[common.Hash][]byte
+
 	// Journal of state modifications. This is the backbone of
 	// Snapshot and RevertToSnapshot.
 	journal        journal
@@ -99,6 +101,7 @@ func New(root common.Hash, db ethdb.Database) (*StateDB, error) {
 		stateObjectsDirty: make(map[common.Address]struct{}),
 		refund:            new(big.Int),
 		logs:              make(map[common.Hash][]*types.Log),
+		preimages:         make(map[common.Hash][]byte),
 	}, nil
 }
 
@@ -120,6 +123,7 @@ func (self *StateDB) New(root common.Hash) (*StateDB, error) {
 		stateObjectsDirty: make(map[common.Address]struct{}),
 		refund:            new(big.Int),
 		logs:              make(map[common.Hash][]*types.Log),
+		preimages:         make(map[common.Hash][]byte),
 	}, nil
 }
 
@@ -141,6 +145,7 @@ func (self *StateDB) Reset(root common.Hash) error {
 	self.txIndex = 0
 	self.logs = make(map[common.Hash][]*types.Log)
 	self.logSize = 0
+	self.preimages = make(map[common.Hash][]byte)
 	self.clearJournalAndRefund()
 
 	return nil
@@ -199,6 +204,21 @@ func (self *StateDB) Logs() []*types.Log {
 	return logs
 }
 
+// AddPreimage records a SHA3 preimage seen by the VM.
+func (self *StateDB) AddPreimage(hash common.Hash, preimage []byte) {
+	if _, ok := self.preimages[hash]; !ok {
+		self.journal = append(self.journal, addPreimageChange{hash: hash})
+		pi := make([]byte, len(preimage))
+		copy(pi, preimage)
+		self.preimages[hash] = pi
+	}
+}
+
+// Preimages returns a list of SHA3 preimages that have been submitted.
+func (self *StateDB) Preimages() map[common.Hash][]byte {
+	return self.preimages
+}
+
 func (self *StateDB) AddRefund(gas *big.Int) {
 	self.journal = append(self.journal, refundChange{prev: new(big.Int).Set(self.refund)})
 	self.refund.Add(self.refund, gas)
@@ -477,8 +497,9 @@ func (self *StateDB) Copy() *StateDB {
 		refund:            new(big.Int).Set(self.refund),
 		logs:              make(map[common.Hash][]*types.Log, len(self.logs)),
 		logSize:           self.logSize,
+		preimages:         make(map[common.Hash][]byte),
 	}
-	// Copy the dirty states and logs
+	// Copy the dirty states, logs, and preimages
 	for addr := range self.stateObjectsDirty {
 		state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state, state.MarkStateObjectDirty)
 		state.stateObjectsDirty[addr] = struct{}{}
@@ -487,6 +508,9 @@ func (self *StateDB) Copy() *StateDB {
 		state.logs[hash] = make([]*types.Log, len(logs))
 		copy(state.logs[hash], logs)
 	}
+	for hash, preimage := range self.preimages {
+		state.preimages[hash] = preimage
+	}
 	return state
 }
 
diff --git a/core/state_processor.go b/core/state_processor.go
index 4f6ca651e..6485e9abd 100644
--- a/core/state_processor.go
+++ b/core/state_processor.go
@@ -99,7 +99,7 @@ func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, s
 	context := NewEVMContext(msg, header, bc)
 	// Create a new environment which holds all relevant information
 	// about the transaction and calling mechanisms.
-	vmenv := vm.NewEVM(context, statedb, config, vm.Config{})
+	vmenv := vm.NewEVM(context, statedb, config, cfg)
 	// Apply the transaction to the current state (included in the env)
 	_, gas, err := ApplyMessage(vmenv, msg, gp)
 	if err != nil {
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 5bfa73a30..3b1b06cca 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -247,7 +247,12 @@ func opMulmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *S
 
 func opSha3(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset, size := stack.pop(), stack.pop()
-	hash := crypto.Keccak256(memory.Get(offset.Int64(), size.Int64()))
+	data := memory.Get(offset.Int64(), size.Int64())
+	hash := crypto.Keccak256(data)
+
+	if env.vmConfig.EnablePreimageRecording {
+		env.StateDB.AddPreimage(common.BytesToHash(hash), data)
+	}
 
 	stack.push(common.BytesToBig(hash))
 	return nil, nil
diff --git a/core/vm/interface.go b/core/vm/interface.go
index 8617b2d0f..6f15112ee 100644
--- a/core/vm/interface.go
+++ b/core/vm/interface.go
@@ -60,6 +60,7 @@ type StateDB interface {
 	Snapshot() int
 
 	AddLog(*types.Log)
+	AddPreimage(common.Hash, []byte)
 }
 
 // Account represents a contract or basic ethereum account.
diff --git a/core/vm/noop.go b/core/vm/noop.go
index ef6837273..7835eeaf3 100644
--- a/core/vm/noop.go
+++ b/core/vm/noop.go
@@ -67,3 +67,4 @@ func (NoopStateDB) Empty(common.Address) bool                         { return f
 func (NoopStateDB) RevertToSnapshot(int)                              {}
 func (NoopStateDB) Snapshot() int                                     { return 0 }
 func (NoopStateDB) AddLog(*types.Log)                                 {}
+func (NoopStateDB) AddPreimage(common.Hash, []byte)                   {}
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 56081f12c..a5f48750d 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -44,6 +44,8 @@ type Config struct {
 	NoRecursion bool
 	// Disable gas metering
 	DisableGasMetering bool
+	// Enable recording of SHA3/keccak preimages
+	EnablePreimageRecording bool
 	// JumpTable contains the EVM instruction table. This
 	// may me left uninitialised and will be set the default
 	// table.
diff --git a/eth/api.go b/eth/api.go
index 023e9a9bb..07df0b79e 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -560,3 +560,9 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 	}
 	return nil, errors.New("database inconsistency")
 }
+
+// Preimage is a debug API function that returns the preimage for a sha3 hash, if known.
+func (api *PrivateDebugAPI) Preimage(ctx context.Context, hash common.Hash) (hexutil.Bytes, error) {
+	db := core.PreimageTable(api.eth.ChainDb())
+	return db.Get(hash.Bytes())
+}
diff --git a/eth/backend.go b/eth/backend.go
index dec8c0c6e..02514c25b 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -33,6 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/eth/filters"
 	"github.com/ethereum/go-ethereum/eth/gasprice"
@@ -97,8 +98,7 @@ type Config struct {
 	GpobaseStepUp           int
 	GpobaseCorrectionFactor int
 
-	EnableJit bool
-	ForceJit  bool
+	EnablePreimageRecording bool
 
 	TestGenesisBlock *types.Block   // Genesis block to seed the chain database with (testing only!)
 	TestGenesisState ethdb.Database // Genesis state to seed the database with (testing only!)
@@ -218,7 +218,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 
 	glog.V(logger.Info).Infoln("Chain config:", eth.chainConfig)
 
-	eth.blockchain, err = core.NewBlockChain(chainDb, eth.chainConfig, eth.pow, eth.EventMux())
+	eth.blockchain, err = core.NewBlockChain(chainDb, eth.chainConfig, eth.pow, eth.EventMux(), vm.Config{EnablePreimageRecording: config.EnablePreimageRecording})
 	if err != nil {
 		if err == core.ErrNoGenesis {
 			return nil, fmt.Errorf(`No chain found. Please initialise a new chain using the "init" subcommand.`)
diff --git a/eth/handler_test.go b/eth/handler_test.go
index 22a4ddf50..8a5d7173b 100644
--- a/eth/handler_test.go
+++ b/eth/handler_test.go
@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/eth/downloader"
 	"github.com/ethereum/go-ethereum/ethdb"
@@ -469,7 +470,7 @@ func testDAOChallenge(t *testing.T, localForked, remoteForked bool, timeout bool
 		db, _         = ethdb.NewMemDatabase()
 		genesis       = core.WriteGenesisBlockForTesting(db)
 		config        = &params.ChainConfig{DAOForkBlock: big.NewInt(1), DAOForkSupport: localForked}
-		blockchain, _ = core.NewBlockChain(db, config, pow, evmux)
+		blockchain, _ = core.NewBlockChain(db, config, pow, evmux, vm.Config{})
 	)
 	pm, err := NewProtocolManager(config, false, NetworkId, 1000, evmux, new(testTxPool), pow, blockchain, db)
 	if err != nil {
diff --git a/eth/helper_test.go b/eth/helper_test.go
index a718a6d21..0861c884b 100644
--- a/eth/helper_test.go
+++ b/eth/helper_test.go
@@ -30,6 +30,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -56,7 +57,7 @@ func newTestProtocolManager(fastSync bool, blocks int, generator func(int, *core
 		db, _         = ethdb.NewMemDatabase()
 		genesis       = core.WriteGenesisBlockForTesting(db, testBank)
 		chainConfig   = &params.ChainConfig{HomesteadBlock: big.NewInt(0)} // homestead set to 0 because of chain maker
-		blockchain, _ = core.NewBlockChain(db, chainConfig, pow, evmux)
+		blockchain, _ = core.NewBlockChain(db, chainConfig, pow, evmux, vm.Config{})
 	)
 	chain, _ := core.GenerateChain(chainConfig, genesis, db, blocks, generator)
 	if _, err := blockchain.InsertChain(chain); err != nil {
diff --git a/internal/web3ext/web3ext.go b/internal/web3ext/web3ext.go
index 12bdb6996..a265d2406 100644
--- a/internal/web3ext/web3ext.go
+++ b/internal/web3ext/web3ext.go
@@ -385,6 +385,12 @@ web3._extend({
 			call: 'debug_traceTransaction',
 			params: 2,
 			inputFormatter: [null, null]
+		}),
+		new web3._extend.Method({
+			name: 'preimage',
+			call: 'debug_preimage',
+			params: 1,
+			inputFormatter: [null]
 		})
 	],
 	properties: []
diff --git a/les/helper_test.go b/les/helper_test.go
index 3d6bf3c29..e0b7558ee 100644
--- a/les/helper_test.go
+++ b/les/helper_test.go
@@ -30,6 +30,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -143,7 +144,7 @@ func newTestProtocolManager(lightSync bool, blocks int, generator func(int, *cor
 		odr = NewLesOdr(db)
 		chain, _ = light.NewLightChain(odr, chainConfig, pow, evmux)
 	} else {
-		blockchain, _ := core.NewBlockChain(db, chainConfig, pow, evmux)
+		blockchain, _ := core.NewBlockChain(db, chainConfig, pow, evmux, vm.Config{})
 		gchain, _ := core.GenerateChain(chainConfig, genesis, db, blocks, generator)
 		if _, err := blockchain.InsertChain(gchain); err != nil {
 			panic(err)
diff --git a/light/odr_test.go b/light/odr_test.go
index 2dcfa40d9..a2f969acb 100644
--- a/light/odr_test.go
+++ b/light/odr_test.go
@@ -251,7 +251,7 @@ func testChainOdr(t *testing.T, protocol int, expFail uint64, fn odrTestFn) {
 	)
 	core.WriteGenesisBlockForTesting(ldb, core.GenesisAccount{Address: testBankAddress, Balance: testBankFunds})
 	// Assemble the test environment
-	blockchain, _ := core.NewBlockChain(sdb, testChainConfig(), pow, evmux)
+	blockchain, _ := core.NewBlockChain(sdb, testChainConfig(), pow, evmux, vm.Config{})
 	chainConfig := &params.ChainConfig{HomesteadBlock: new(big.Int)}
 	gchain, _ := core.GenerateChain(chainConfig, genesis, sdb, 4, testChainGen)
 	if _, err := blockchain.InsertChain(gchain); err != nil {
diff --git a/light/txpool_test.go b/light/txpool_test.go
index e5a4670aa..d8f04e617 100644
--- a/light/txpool_test.go
+++ b/light/txpool_test.go
@@ -25,6 +25,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/params"
@@ -88,7 +89,7 @@ func TestTxPool(t *testing.T) {
 	)
 	core.WriteGenesisBlockForTesting(ldb, core.GenesisAccount{Address: testBankAddress, Balance: testBankFunds})
 	// Assemble the test environment
-	blockchain, _ := core.NewBlockChain(sdb, testChainConfig(), pow, evmux)
+	blockchain, _ := core.NewBlockChain(sdb, testChainConfig(), pow, evmux, vm.Config{})
 	chainConfig := &params.ChainConfig{HomesteadBlock: new(big.Int)}
 	gchain, _ := core.GenerateChain(chainConfig, genesis, sdb, poolTestBlocks, txPoolTestChainGen)
 	if _, err := blockchain.InsertChain(gchain); err != nil {
diff --git a/light/vm_env.go b/light/vm_env.go
index 1b225c8de..d2cc7e960 100644
--- a/light/vm_env.go
+++ b/light/vm_env.go
@@ -45,6 +45,8 @@ func (s *VMState) Error() error {
 
 func (s *VMState) AddLog(log *types.Log) {}
 
+func (s *VMState) AddPreimage(hash common.Hash, preimage []byte) {}
+
 // errHandler handles and stores any state error that happens during execution.
 func (s *VMState) errHandler(err error) {
 	if err != nil && s.err == nil {
diff --git a/tests/block_test_util.go b/tests/block_test_util.go
index ea63c9996..470eb7cb7 100644
--- a/tests/block_test_util.go
+++ b/tests/block_test_util.go
@@ -31,6 +31,7 @@ import (
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -172,7 +173,7 @@ func runBlockTest(homesteadBlock, daoForkBlock, gasPriceFork *big.Int, test *Blo
 	core.WriteHeadBlockHash(db, test.Genesis.Hash())
 	evmux := new(event.TypeMux)
 	config := &params.ChainConfig{HomesteadBlock: homesteadBlock, DAOForkBlock: daoForkBlock, DAOForkSupport: true, EIP150Block: gasPriceFork}
-	chain, err := core.NewBlockChain(db, config, ethash.NewShared(), evmux)
+	chain, err := core.NewBlockChain(db, config, ethash.NewShared(), evmux, vm.Config{})
 	if err != nil {
 		return err
 	}