diff --git a/alethzero/MainWin.cpp b/alethzero/MainWin.cpp
index 8cde476c3..fce3200cb 100644
--- a/alethzero/MainWin.cpp
+++ b/alethzero/MainWin.cpp
@@ -805,6 +805,7 @@ void Main::readSettings(bool _skipGeometry)
 	ui->usePrivate->setChecked(m_privateChain.size());
 	ui->verbosity->setValue(s.value("verbosity", 1).toInt());
 	ui->jitvm->setChecked(s.value("jitvm", true).toBool());
+	on_jitvm_triggered();
 
 	ui->urlEdit->setText(s.value("url", "about:blank").toString());	//http://gavwood.com/gavcoin.html
 	on_urlEdit_returnPressed();
diff --git a/cmake/EthCompilerSettings.cmake b/cmake/EthCompilerSettings.cmake
index eb8588ceb..53535a489 100644
--- a/cmake/EthCompilerSettings.cmake
+++ b/cmake/EthCompilerSettings.cmake
@@ -21,7 +21,7 @@ elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
 	set(CMAKE_CXX_FLAGS_DEBUG          "-O0 -g -DETH_DEBUG")
 	set(CMAKE_CXX_FLAGS_MINSIZEREL     "-Os -DNDEBUG -DETH_RELEASE")
 	set(CMAKE_CXX_FLAGS_RELEASE        "-O3 -DNDEBUG -DETH_RELEASE")
-	set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g -DETH_DEBUG")
+	set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g -DETH_RELEASE")
 
 	if ("${CMAKE_SYSTEM_NAME}" MATCHES "Linux")
 		set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libstdc++ -fcolor-diagnostics -Qunused-arguments -DBOOST_ASIO_HAS_CLANG_LIBCXX")
diff --git a/evmjit/libevmjit-cpp/JitVM.cpp b/evmjit/libevmjit-cpp/JitVM.cpp
index 0d6a6e00a..68161526d 100644
--- a/evmjit/libevmjit-cpp/JitVM.cpp
+++ b/evmjit/libevmjit-cpp/JitVM.cpp
@@ -51,7 +51,7 @@ bytesConstRef JitVM::execImpl(u256& io_gas, ExtVMFace& _ext, OnOpFunc const& _on
 	m_data.timestamp 	= static_cast<decltype(m_data.timestamp)>(_ext.currentBlock.timestamp);
 	m_data.code     	= _ext.code.data();
 	m_data.codeSize 	= _ext.code.size();
-	m_data.codeHash		= eth2llvm(sha3(_ext.code));
+	m_data.codeHash		= eth2llvm(_ext.codeHash);
 
 	auto env = reinterpret_cast<Env*>(&_ext);
 	auto exitCode = m_engine.run(&m_data, env);
diff --git a/libdevcrypto/CryptoPP.cpp b/libdevcrypto/CryptoPP.cpp
index b701fed8d..9fffe784e 100644
--- a/libdevcrypto/CryptoPP.cpp
+++ b/libdevcrypto/CryptoPP.cpp
@@ -264,7 +264,6 @@ Public Secp256k1::recover(Signature _signature, bytesConstRef _message)
 	
 	ECP::Element x;
 	{
-		Guard l(x_curve);
 		m_curve.DecodePoint(x, encodedpoint, 33);
 		if (!m_curve.VerifyPoint(x))
 			return recovered;
@@ -286,7 +285,6 @@ Public Secp256k1::recover(Signature _signature, bytesConstRef _message)
 	ECP::Point p;
 	byte recoveredbytes[65];
 	{
-		Guard l(x_curve);
 		// todo: make generator member
 		p = m_curve.CascadeMultiply(u2, x, u1, m_params.GetSubgroupGenerator());
 		m_curve.EncodePoint(recoveredbytes, p, false);
diff --git a/libethereum/BlockChain.cpp b/libethereum/BlockChain.cpp
index 67e42d7c8..1c4d0073f 100644
--- a/libethereum/BlockChain.cpp
+++ b/libethereum/BlockChain.cpp
@@ -35,6 +35,7 @@
 #include <libdevcore/StructuredLogger.h>
 #include <libdevcore/FileSystem.h>
 #include <libethcore/Exceptions.h>
+#include <libethcore/EthashAux.h>
 #include <libethcore/ProofOfWork.h>
 #include <libethcore/BlockInfo.h>
 #include <libethcore/Params.h>
@@ -42,6 +43,7 @@
 #include "GenesisInfo.h"
 #include "State.h"
 #include "Defaults.h"
+
 using namespace std;
 using namespace dev;
 using namespace dev::eth;
@@ -307,7 +309,7 @@ tuple<h256s, h256s, bool> BlockChain::sync(BlockQueue& _bq, OverlayDB const& _st
 {
 //	_bq.tick(*this);
 
-	vector<pair<BlockInfo, bytes>> blocks;
+	VerifiedBlocks blocks;
 	_bq.drain(blocks, _max);
 
 	h256s fresh;
@@ -320,7 +322,7 @@ tuple<h256s, h256s, bool> BlockChain::sync(BlockQueue& _bq, OverlayDB const& _st
 			// Nonce & uncle nonces already verified in verification thread at this point.
 			ImportRoute r;
 			DEV_TIMED_ABOVE(Block import, 500)
-				r = import(block.first, block.second, _stateDB, ImportRequirements::Default & ~ImportRequirements::ValidNonce & ~ImportRequirements::CheckUncles);
+				r = import(block.verified, _stateDB, ImportRequirements::Default & ~ImportRequirements::ValidNonce & ~ImportRequirements::CheckUncles);
 			fresh += r.first;
 			dead += r.second;
 		}
@@ -329,14 +331,14 @@ tuple<h256s, h256s, bool> BlockChain::sync(BlockQueue& _bq, OverlayDB const& _st
 			cwarn << "ODD: Import queue contains block with unknown parent." << LogTag::Error << boost::current_exception_diagnostic_information();
 			// NOTE: don't reimport since the queue should guarantee everything in the right order.
 			// Can't continue - chain bad.
-			badBlocks.push_back(block.first.hash());
+			badBlocks.push_back(block.verified.info.hash());
 		}
 		catch (Exception const& _e)
 		{
 			cnote << "Exception while importing block. Someone (Jeff? That you?) seems to be giving us dodgy blocks!" << LogTag::Error << diagnostic_information(_e);
 			// NOTE: don't reimport since the queue should guarantee everything in the right order.
 			// Can't continue - chain  bad.
-			badBlocks.push_back(block.first.hash());
+			badBlocks.push_back(block.verified.info.hash());
 		}
 	}
 	return make_tuple(fresh, dead, _bq.doneDrain(badBlocks));
@@ -346,7 +348,7 @@ pair<ImportResult, ImportRoute> BlockChain::attemptImport(bytes const& _block, O
 {
 	try
 	{
-		return make_pair(ImportResult::Success, import(_block, _stateDB, _ir));
+		return make_pair(ImportResult::Success, import(verifyBlock(_block, _ir), _stateDB, _ir));
 	}
 	catch (UnknownParent&)
 	{
@@ -369,14 +371,13 @@ pair<ImportResult, ImportRoute> BlockChain::attemptImport(bytes const& _block, O
 ImportRoute BlockChain::import(bytes const& _block, OverlayDB const& _db, ImportRequirements::value _ir)
 {
 	// VERIFY: populates from the block and checks the block is internally coherent.
-	BlockInfo bi;
+	VerifiedBlockRef block;
 
 #if ETH_CATCH
 	try
 #endif
 	{
-		bi.populate(&_block);
-		bi.verifyInternals(&_block);
+		block = verifyBlock(_block, _ir);
 	}
 #if ETH_CATCH
 	catch (Exception const& _e)
@@ -387,10 +388,10 @@ ImportRoute BlockChain::import(bytes const& _block, OverlayDB const& _db, Import
 	}
 #endif
 
-	return import(bi, _block, _db, _ir);
+	return import(block, _db, _ir);
 }
 
-ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, OverlayDB const& _db, ImportRequirements::value _ir)
+ImportRoute BlockChain::import(VerifiedBlockRef const& _block, OverlayDB const& _db, ImportRequirements::value _ir)
 {
 	//@tidy This is a behemoth of a method - could do to be split into a few smaller ones.
 
@@ -405,28 +406,28 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 #endif
 
 	// Check block doesn't already exist first!
-	if (isKnown(_bi.hash()) && (_ir & ImportRequirements::DontHave))
+	if (isKnown(_block.info.hash()) && (_ir & ImportRequirements::DontHave))
 	{
-		clog(BlockChainNote) << _bi.hash() << ": Not new.";
+		clog(BlockChainNote) << _block.info.hash() << ": Not new.";
 		BOOST_THROW_EXCEPTION(AlreadyHaveBlock());
 	}
 
 	// Work out its number as the parent's number + 1
-	if (!isKnown(_bi.parentHash))
+	if (!isKnown(_block.info.parentHash))
 	{
-		clog(BlockChainNote) << _bi.hash() << ": Unknown parent " << _bi.parentHash;
+		clog(BlockChainNote) << _block.info.hash() << ": Unknown parent " << _block.info.parentHash;
 		// We don't know the parent (yet) - discard for now. It'll get resent to us if we find out about its ancestry later on.
 		BOOST_THROW_EXCEPTION(UnknownParent());
 	}
 
-	auto pd = details(_bi.parentHash);
+	auto pd = details(_block.info.parentHash);
 	if (!pd)
 	{
 		auto pdata = pd.rlp();
 		clog(BlockChainDebug) << "Details is returning false despite block known:" << RLP(pdata);
-		auto parentBlock = block(_bi.parentHash);
-		clog(BlockChainDebug) << "isKnown:" << isKnown(_bi.parentHash);
-		clog(BlockChainDebug) << "last/number:" << m_lastBlockNumber << m_lastBlockHash << _bi.number;
+		auto parentBlock = block(_block.info.parentHash);
+		clog(BlockChainDebug) << "isKnown:" << isKnown(_block.info.parentHash);
+		clog(BlockChainDebug) << "last/number:" << m_lastBlockNumber << m_lastBlockHash << _block.info.number;
 		clog(BlockChainDebug) << "Block:" << BlockInfo(parentBlock);
 		clog(BlockChainDebug) << "RLP:" << RLP(parentBlock);
 		clog(BlockChainDebug) << "DATABASE CORRUPTION: CRITICAL FAILURE";
@@ -434,14 +435,14 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 	}
 
 	// Check it's not crazy
-	if (_bi.timestamp > (u256)time(0))
+	if (_block.info.timestamp > (u256)time(0))
 	{
-		clog(BlockChainChat) << _bi.hash() << ": Future time " << _bi.timestamp << " (now at " << time(0) << ")";
+		clog(BlockChainChat) << _block.info.hash() << ": Future time " << _block.info.timestamp << " (now at " << time(0) << ")";
 		// Block has a timestamp in the future. This is no good.
 		BOOST_THROW_EXCEPTION(FutureTime());
 	}
 
-	clog(BlockChainChat) << "Attempting import of " << _bi.hash() << "...";
+	clog(BlockChainChat) << "Attempting import of " << _block.info.hash() << "...";
 
 #if ETH_TIMED_IMPORTS
 	preliminaryChecks = t.elapsed();
@@ -461,7 +462,7 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 		// Check transactions are valid and that they result in a state equivalent to our state_root.
 		// Get total difficulty increase and update state, checking it.
 		State s(_db);
-		auto tdIncrease = s.enactOn(&_block, _bi, *this, _ir);
+		auto tdIncrease = s.enactOn(_block, *this, _ir);
 
 		BlockLogBlooms blb;
 		BlockReceipts br;
@@ -497,22 +498,22 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 		// together with an "ensureCachedWithUpdatableLock(l)" method.
 		// This is safe in practice since the caches don't get flushed nearly often enough to be
 		// done here.
-		details(_bi.parentHash);
+		details(_block.info.parentHash);
 		DEV_WRITE_GUARDED(x_details)
-			m_details[_bi.parentHash].children.push_back(_bi.hash());
+			m_details[_block.info.parentHash].children.push_back(_block.info.hash());
 
 #if ETH_TIMED_IMPORTS || !ETH_TRUE
 		collation = t.elapsed();
 		t.restart();
 #endif
 
-		blocksBatch.Put(toSlice(_bi.hash()), (ldb::Slice)ref(_block));
+		blocksBatch.Put(toSlice(_block.info.hash()), ldb::Slice(_block.block));
 		DEV_READ_GUARDED(x_details)
-			extrasBatch.Put(toSlice(_bi.parentHash, ExtraDetails), (ldb::Slice)dev::ref(m_details[_bi.parentHash].rlp()));
+			extrasBatch.Put(toSlice(_block.info.parentHash, ExtraDetails), (ldb::Slice)dev::ref(m_details[_block.info.parentHash].rlp()));
 
-		extrasBatch.Put(toSlice(_bi.hash(), ExtraDetails), (ldb::Slice)dev::ref(BlockDetails((unsigned)pd.number + 1, td, _bi.parentHash, {}).rlp()));
-		extrasBatch.Put(toSlice(_bi.hash(), ExtraLogBlooms), (ldb::Slice)dev::ref(blb.rlp()));
-		extrasBatch.Put(toSlice(_bi.hash(), ExtraReceipts), (ldb::Slice)dev::ref(br.rlp()));
+		extrasBatch.Put(toSlice(_block.info.hash(), ExtraDetails), (ldb::Slice)dev::ref(BlockDetails((unsigned)pd.number + 1, td, _block.info.parentHash, {}).rlp()));
+		extrasBatch.Put(toSlice(_block.info.hash(), ExtraLogBlooms), (ldb::Slice)dev::ref(blb.rlp()));
+		extrasBatch.Put(toSlice(_block.info.hash(), ExtraReceipts), (ldb::Slice)dev::ref(br.rlp()));
 
 #if ETH_TIMED_IMPORTS || !ETH_TRUE
 		writing = t.elapsed();
@@ -530,20 +531,20 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 	{
 		clog(BlockChainWarn) << "   Malformed block: " << diagnostic_information(_e);
 		_e << errinfo_comment("Malformed block ");
-		clog(BlockChainWarn) << "Block: " << _bi.hash();
-		clog(BlockChainWarn) << _bi;
-		clog(BlockChainWarn) << "Block parent: " << _bi.parentHash;
-		clog(BlockChainWarn) << BlockInfo(block(_bi.parentHash));
+		clog(BlockChainWarn) << "Block: " << _block.info.hash();
+		clog(BlockChainWarn) << _block.info;
+		clog(BlockChainWarn) << "Block parent: " << _block.info.parentHash;
+		clog(BlockChainWarn) << BlockInfo(block(_block.info.parentHash));
 		throw;
 	}
 #endif
 
 	StructuredLogger::chainReceivedNewBlock(
-		_bi.headerHash(WithoutNonce).abridged(),
-		_bi.nonce.abridged(),
+		_block.info.headerHash(WithoutNonce).abridged(),
+		_block.info.nonce.abridged(),
 		currentHash().abridged(),
 		"", // TODO: remote id ??
-		_bi.parentHash.abridged()
+		_block.info.parentHash.abridged()
 	);
 	//	cnote << "Parent " << bi.parentHash << " has " << details(bi.parentHash).children.size() << " children.";
 
@@ -556,8 +557,8 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 		// don't include bi.hash() in treeRoute, since it's not yet in details DB...
 		// just tack it on afterwards.
 		unsigned commonIndex;
-		tie(route, common, commonIndex) = treeRoute(last, _bi.parentHash);
-		route.push_back(_bi.hash());
+		tie(route, common, commonIndex) = treeRoute(last, _block.info.parentHash);
+		route.push_back(_block.info.hash());
 
 		// Most of the time these two will be equal - only when we're doing a chain revert will they not be
 		if (common != last)
@@ -569,8 +570,8 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 		for (auto i = route.rbegin(); i != route.rend() && *i != common; ++i)
 		{
 			BlockInfo tbi;
-			if (*i == _bi.hash())
-				tbi = _bi;
+			if (*i == _block.info.hash())
+				tbi = _block.info;
 			else
 				tbi = BlockInfo(block(*i));
 
@@ -597,7 +598,7 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 			h256s newTransactionAddresses;
 			{
 				bytes blockBytes;
-				RLP blockRLP(*i == _bi.hash() ? _block : (blockBytes = block(*i)));
+				RLP blockRLP(*i == _block.info.hash() ? _block.block : &(blockBytes = block(*i)));
 				TransactionAddress ta;
 				ta.blockHash = tbi.hash();
 				for (ta.index = 0; ta.index < blockRLP[1].itemCount(); ++ta.index)
@@ -613,17 +614,17 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 
 		// FINALLY! change our best hash.
 		{
-			newLastBlockHash = _bi.hash();
-			newLastBlockNumber = (unsigned)_bi.number;
+			newLastBlockHash = _block.info.hash();
+			newLastBlockNumber = (unsigned)_block.info.number;
 		}
 
-		clog(BlockChainNote) << "   Imported and best" << td << " (#" << _bi.number << "). Has" << (details(_bi.parentHash).children.size() - 1) << "siblings. Route:" << route;
+		clog(BlockChainNote) << "   Imported and best" << td << " (#" << _block.info.number << "). Has" << (details(_block.info.parentHash).children.size() - 1) << "siblings. Route:" << route;
 
 		StructuredLogger::chainNewHead(
-			_bi.headerHash(WithoutNonce).abridged(),
-			_bi.nonce.abridged(),
+			_block.info.headerHash(WithoutNonce).abridged(),
+			_block.info.nonce.abridged(),
 			currentHash().abridged(),
-			_bi.parentHash.abridged()
+			_block.info.parentHash.abridged()
 		);
 	}
 	else
@@ -634,24 +635,26 @@ ImportRoute BlockChain::import(BlockInfo const& _bi, bytes const& _block, Overla
 	m_blocksDB->Write(m_writeOptions, &blocksBatch);
 	m_extrasDB->Write(m_writeOptions, &extrasBatch);
 
-	if (isKnown(_bi.hash()) && !details(_bi.hash()))
+#if ETH_DEBUG || !ETH_TRUE
+	if (isKnown(_block.info.hash()) && !details(_block.info.hash()))
 	{
 		clog(BlockChainDebug) << "Known block just inserted has no details.";
-		clog(BlockChainDebug) << "Block:" << _bi;
+		clog(BlockChainDebug) << "Block:" << _block.info;
 		clog(BlockChainDebug) << "DATABASE CORRUPTION: CRITICAL FAILURE";
 		exit(-1);
 	}
 
 	try {
-		State canary(_db, *this, _bi.hash(), ImportRequirements::DontHave);
+		State canary(_db, *this, _block.info.hash(), ImportRequirements::DontHave);
 	}
 	catch (...)
 	{
 		clog(BlockChainDebug) << "Failed to initialise State object form imported block.";
-		clog(BlockChainDebug) << "Block:" << _bi;
+		clog(BlockChainDebug) << "Block:" << _block.info;
 		clog(BlockChainDebug) << "DATABASE CORRUPTION: CRITICAL FAILURE";
 		exit(-1);
 	}
+#endif
 
 	if (m_lastBlockHash != newLastBlockHash)
 		DEV_WRITE_GUARDED(x_lastBlockHash)
@@ -1054,3 +1057,78 @@ bytes BlockChain::block(h256 const& _hash) const
 
 	return m_blocks[_hash];
 }
+
+VerifiedBlockRef BlockChain::verifyBlock(bytes const& _block, ImportRequirements::value)
+{
+	VerifiedBlockRef res;
+	try
+	{
+		res.info.populate(_block, CheckEverything);
+		res.info.verifyInternals(&_block);
+	}
+	catch (InvalidBlockNonce&)
+	{
+		badBlock(_block, "Invalid block nonce");
+		cwarn << "  Nonce:" << res.info.nonce.hex();
+		cwarn << "  PoWHash:" << res.info.headerHash(WithoutNonce).hex();
+		cwarn << "  SeedHash:" << res.info.seedHash().hex();
+		cwarn << "  Target:" << res.info.boundary().hex();
+		cwarn << "  MixHash:" << res.info.mixHash.hex();
+		Ethash::Result er = EthashAux::eval(res.info.seedHash(), res.info.headerHash(WithoutNonce), res.info.nonce);
+		cwarn << "  Ethash v:" << er.value.hex();
+		cwarn << "  Ethash mH:" << er.mixHash.hex();
+		throw;
+	}
+	catch (Exception& _e)
+	{
+		badBlock(_block, _e.what());
+		throw;
+	}
+
+	RLP r(&_block);
+	for (auto const& uncle: r[2])
+	{
+		try
+		{
+			BlockInfo().populateFromHeader(RLP(uncle.data()), CheckEverything);
+		}
+		catch (InvalidNonce&)
+		{
+			badBlockHeader(uncle.data(), "Invalid uncle nonce");
+			BlockInfo bi = BlockInfo::fromHeader(uncle.data(), CheckNothing);
+			cwarn << "  Nonce:" << bi.nonce.hex();
+			cwarn << "  PoWHash:" << bi.headerHash(WithoutNonce).hex();
+			cwarn << "  SeedHash:" << bi.seedHash().hex();
+			cwarn << "  Target:" << bi.boundary().hex();
+			cwarn << "  MixHash:" << bi.mixHash.hex();
+			Ethash::Result er = EthashAux::eval(bi.seedHash(), bi.headerHash(WithoutNonce), bi.nonce);
+			cwarn << "  Ethash v:" << er.value.hex();
+			cwarn << "  Ethash mH:" << er.mixHash.hex();
+			throw;
+		}
+		catch (Exception& _e)
+		{
+			badBlockHeader(uncle.data(), _e.what());
+			throw;
+		}
+	}
+
+	unsigned i = 0;
+	for (auto const& tr: r[1])
+	{
+		try
+		{
+			res.transactions.push_back(Transaction(tr.data(), CheckTransaction::Everything));
+		}
+		catch (...)
+		{
+			badBlock(_block, "Invalid transaction");
+			cwarn << "  Transaction Index:" << i;
+			throw;
+		}
+		++i;
+	}
+	res.block = bytesConstRef(&_block);
+	return move(res);
+}
+
diff --git a/libethereum/BlockChain.h b/libethereum/BlockChain.h
index a67ec9a9c..e05de885a 100644
--- a/libethereum/BlockChain.h
+++ b/libethereum/BlockChain.h
@@ -40,6 +40,7 @@
 #include "Account.h"
 #include "Transaction.h"
 #include "BlockQueue.h"
+#include "VerifiedBlock.h"
 namespace ldb = leveldb;
 
 namespace std
@@ -120,7 +121,7 @@ public:
 	/// Import block into disk-backed DB
 	/// @returns the block hashes of any blocks that came into/went out of the canonical block chain.
 	ImportRoute import(bytes const& _block, OverlayDB const& _stateDB, ImportRequirements::value _ir = ImportRequirements::Default);
-	ImportRoute import(BlockInfo const& _bi, bytes const& _block, OverlayDB const& _stateDB, ImportRequirements::value _ir = ImportRequirements::Default);
+	ImportRoute import(VerifiedBlockRef const& _block, OverlayDB const& _db, ImportRequirements::value _ir = ImportRequirements::Default);
 
 	/// Returns true if the given block is known (though not necessarily a part of the canon chain).
 	bool isKnown(h256 const& _hash) const;
@@ -256,6 +257,9 @@ public:
 	/// Deallocate unused data.
 	void garbageCollect(bool _force = false);
 
+	/// Verify block and prepare it for enactment
+	static VerifiedBlockRef verifyBlock(bytes const& _block, ImportRequirements::value _ir = ImportRequirements::Default);
+
 private:
 	static h256 chunkId(unsigned _level, unsigned _index) { return h256(_index * 0xff + _level); }
 
diff --git a/libethereum/BlockQueue.cpp b/libethereum/BlockQueue.cpp
index 360bf915e..b6d427e29 100644
--- a/libethereum/BlockQueue.cpp
+++ b/libethereum/BlockQueue.cpp
@@ -22,10 +22,11 @@
 #include "BlockQueue.h"
 #include <thread>
 #include <libdevcore/Log.h>
-#include <libethcore/EthashAux.h>
 #include <libethcore/Exceptions.h>
 #include <libethcore/BlockInfo.h>
 #include "BlockChain.h"
+#include "VerifiedBlock.h"
+
 using namespace std;
 using namespace dev;
 using namespace dev::eth;
@@ -71,62 +72,14 @@ void BlockQueue::verifierBody()
 			m_unverified.pop_front();
 			BlockInfo bi;
 			bi.mixHash = work.first;
-			m_verifying.push_back(make_pair(bi, bytes()));
+			m_verifying.push_back(VerifiedBlock { VerifiedBlockRef { bytesConstRef(), move(bi), Transactions() }, bytes() });
 		}
 
-		std::pair<BlockInfo, bytes> res;
-		swap(work.second, res.second);
-		try {
-			try {
-				res.first.populate(res.second, CheckEverything, work.first);
-				res.first.verifyInternals(&res.second);
-			}
-			catch (InvalidBlockNonce&)
-			{
-				badBlock(res.second, "Invalid block nonce");
-				cwarn << "  Nonce:" << res.first.nonce.hex();
-				cwarn << "  PoWHash:" << res.first.headerHash(WithoutNonce).hex();
-				cwarn << "  SeedHash:" << res.first.seedHash().hex();
-				cwarn << "  Target:" << res.first.boundary().hex();
-				cwarn << "  MixHash:" << res.first.mixHash.hex();
-				Ethash::Result er = EthashAux::eval(res.first.seedHash(), res.first.headerHash(WithoutNonce), res.first.nonce);
-				cwarn << "  Ethash v:" << er.value.hex();
-				cwarn << "  Ethash mH:" << er.mixHash.hex();
-				throw;
-			}
-			catch (Exception& _e)
-			{
-				badBlock(res.second, _e.what());
-				throw;
-			}
-
-			RLP r(&res.second);
-			for (auto const& uncle: r[2])
-			{
-				try
-				{
-					BlockInfo().populateFromHeader(RLP(uncle.data()), CheckEverything);
-				}
-				catch (InvalidNonce&)
-				{
-					badBlockHeader(uncle.data(), "Invalid uncle nonce");
-					BlockInfo bi = BlockInfo::fromHeader(uncle.data(), CheckNothing);
-					cwarn << "  Nonce:" << bi.nonce.hex();
-					cwarn << "  PoWHash:" << bi.headerHash(WithoutNonce).hex();
-					cwarn << "  SeedHash:" << bi.seedHash().hex();
-					cwarn << "  Target:" << bi.boundary().hex();
-					cwarn << "  MixHash:" << bi.mixHash.hex();
-					Ethash::Result er = EthashAux::eval(bi.seedHash(), bi.headerHash(WithoutNonce), bi.nonce);
-					cwarn << "  Ethash v:" << er.value.hex();
-					cwarn << "  Ethash mH:" << er.mixHash.hex();
-					throw;
-				}
-				catch (Exception& _e)
-				{
-					badBlockHeader(uncle.data(), _e.what());
-					throw;
-				}
-			}
+		VerifiedBlock res;
+		swap(work.second, res.blockData);
+		try
+		{
+			res.verified = BlockChain::verifyBlock(res.blockData);
 		}
 		catch (...)
 		{
@@ -141,7 +94,7 @@ void BlockQueue::verifierBody()
 
 			unique_lock<Mutex> l(m_verification);
 			for (auto it = m_verifying.begin(); it != m_verifying.end(); ++it)
-				if (it->first.mixHash == work.first)
+				if (it->verified.info.mixHash == work.first)
 				{
 					m_verifying.erase(it);
 					goto OK1;
@@ -154,12 +107,12 @@ void BlockQueue::verifierBody()
 		bool ready = false;
 		{
 			unique_lock<Mutex> l(m_verification);
-			if (m_verifying.front().first.mixHash == work.first)
+			if (m_verifying.front().verified.info.mixHash == work.first)
 			{
 				// we're next!
 				m_verifying.pop_front();
 				m_verified.push_back(move(res));
-				while (m_verifying.size() && !m_verifying.front().second.empty())
+				while (m_verifying.size() && !m_verifying.front().blockData.empty())
 				{
 					m_verified.push_back(move(m_verifying.front()));
 					m_verifying.pop_front();
@@ -169,7 +122,7 @@ void BlockQueue::verifierBody()
 			else
 			{
 				for (auto& i: m_verifying)
-					if (i.first.mixHash == work.first)
+					if (i.verified.info.mixHash == work.first)
 					{
 						i = move(res);
 						goto OK;
@@ -277,15 +230,15 @@ bool BlockQueue::doneDrain(h256s const& _bad)
 	m_drainingSet.clear();
 	if (_bad.size())
 	{
-		vector<pair<BlockInfo, bytes>> old;
+		vector<VerifiedBlock> old;
 		DEV_GUARDED(m_verification)
 			swap(m_verified, old);
 		for (auto& b: old)
 		{
-			if (m_knownBad.count(b.first.parentHash))
+			if (m_knownBad.count(b.verified.info.parentHash))
 			{
-				m_knownBad.insert(b.first.hash());
-				m_readySet.erase(b.first.hash());
+				m_knownBad.insert(b.verified.info.hash());
+				m_readySet.erase(b.verified.info.hash());
 			}
 			else
 				DEV_GUARDED(m_verification)
@@ -348,7 +301,7 @@ QueueStatus BlockQueue::blockStatus(h256 const& _h) const
 			QueueStatus::Unknown;
 }
 
-void BlockQueue::drain(std::vector<std::pair<BlockInfo, bytes>>& o_out, unsigned _max)
+void BlockQueue::drain(VerifiedBlocks& o_out, unsigned _max)
 {
 	WriteGuard l(m_lock);
 	DEV_INVARIANT_CHECK;
@@ -364,7 +317,7 @@ void BlockQueue::drain(std::vector<std::pair<BlockInfo, bytes>>& o_out, unsigned
 		for (auto const& bs: o_out)
 		{
 			// TODO: @optimise use map<h256, bytes> rather than vector<bytes> & set<h256>.
-			auto h = bs.first.hash();
+			auto h = bs.verified.info.hash();
 			m_drainingSet.insert(h);
 			m_readySet.erase(h);
 		}
diff --git a/libethereum/BlockQueue.h b/libethereum/BlockQueue.h
index 45043559b..0473f173f 100644
--- a/libethereum/BlockQueue.h
+++ b/libethereum/BlockQueue.h
@@ -31,6 +31,7 @@
 #include <libdevcore/Guards.h>
 #include <libethcore/Common.h>
 #include <libethcore/BlockInfo.h>
+#include "VerifiedBlock.h"
 
 namespace dev
 {
@@ -81,7 +82,7 @@ public:
 
 	/// Grabs at most @a _max of the blocks that are ready, giving them in the correct order for insertion into the chain.
 	/// Don't forget to call doneDrain() once you're done importing.
-	void drain(std::vector<std::pair<BlockInfo, bytes>>& o_out, unsigned _max);
+	void drain(std::vector<VerifiedBlock>& o_out, unsigned _max);
 
 	/// Must be called after a drain() call. Notes that the drained blocks have been imported into the blockchain, so we can forget about them.
 	/// @returns true iff there are additional blocks ready to be processed.
@@ -128,8 +129,8 @@ private:
 
 	mutable Mutex m_verification;										///< Mutex that allows writing to m_verified, m_verifying and m_unverified.
 	std::condition_variable m_moreToVerify;								///< Signaled when m_unverified has a new entry.
-	std::vector<std::pair<BlockInfo, bytes>> m_verified;				///< List of blocks, in correct order, verified and ready for chain-import.
-	std::deque<std::pair<BlockInfo, bytes>> m_verifying;				///< List of blocks being verified; as long as the second component (bytes) is empty, it's not finished.
+	std::vector<VerifiedBlock> m_verified;				///< List of blocks, in correct order, verified and ready for chain-import.
+	std::deque<VerifiedBlock> m_verifying;				///< List of blocks being verified; as long as the second component (bytes) is empty, it's not finished.
 	std::deque<std::pair<h256, bytes>> m_unverified;					///< List of blocks, in correct order, ready for verification.
 
 	std::vector<std::thread> m_verifiers;								///< Threads who only verify.
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 10481cdf0..1caaac9c2 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -174,7 +174,7 @@ Client::Client(p2p::Host* _extNet, std::string const& _dbPath, WithExisting _for
 }
 
 Client::Client(p2p::Host* _extNet, std::shared_ptr<GasPricer> _gp, std::string const& _dbPath, WithExisting _forceAction, u256 _networkId):
-	Worker("eth"),
+	Worker("eth", 0),
 	m_vc(_dbPath),
 	m_bc(_dbPath, max(m_vc.action(), _forceAction), [](unsigned d, unsigned t){ cerr << "REVISING BLOCKCHAIN: Processed " << d << " of " << t << "...\r"; }),
 	m_gp(_gp),
diff --git a/libethereum/Executive.cpp b/libethereum/Executive.cpp
index 5ec5f7313..7acef5cd6 100644
--- a/libethereum/Executive.cpp
+++ b/libethereum/Executive.cpp
@@ -151,7 +151,8 @@ bool Executive::call(CallParameters const& _p, u256 const& _gasPrice, Address co
 		{
 			m_outRef = _p.out; // Save ref to expected output buffer to be used in go()
 			bytes const& c = m_s.code(_p.codeAddress);
-			m_ext = make_shared<ExtVM>(m_s, m_lastHashes, _p.receiveAddress, _p.senderAddress, _origin, _p.value, _gasPrice, _p.data, &c, m_depth);
+			h256 codeHash = m_s.codeHash(_p.codeAddress);
+			m_ext = make_shared<ExtVM>(m_s, m_lastHashes, _p.receiveAddress, _p.senderAddress, _origin, _p.value, _gasPrice, _p.data, &c, codeHash, m_depth);
 		}
 	}
 
@@ -171,7 +172,7 @@ bool Executive::create(Address _sender, u256 _endowment, u256 _gasPrice, u256 _g
 
 	// Execute _init.
 	if (!_init.empty())
-		m_ext = make_shared<ExtVM>(m_s, m_lastHashes, m_newAddress, _sender, _origin, _endowment, _gasPrice, bytesConstRef(), _init, m_depth);
+		m_ext = make_shared<ExtVM>(m_s, m_lastHashes, m_newAddress, _sender, _origin, _endowment, _gasPrice, bytesConstRef(), _init, sha3(_init), m_depth);
 
 	m_s.m_cache[m_newAddress] = Account(m_s.balance(m_newAddress), Account::ContractConception);
 	m_s.transferBalance(_sender, m_newAddress, _endowment);
diff --git a/libethereum/ExtVM.h b/libethereum/ExtVM.h
index babff4edf..853787493 100644
--- a/libethereum/ExtVM.h
+++ b/libethereum/ExtVM.h
@@ -39,8 +39,8 @@ class ExtVM: public ExtVMFace
 {
 public:
 	/// Full constructor.
-	ExtVM(State& _s, LastHashes const& _lh, Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytesConstRef _code, unsigned _depth = 0):
-		ExtVMFace(_myAddress, _caller, _origin, _value, _gasPrice, _data, _code.toBytes(), _s.m_previousBlock, _s.m_currentBlock, _lh, _depth), m_s(_s), m_origCache(_s.m_cache)
+	ExtVM(State& _s, LastHashes const& _lh, Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytesConstRef _code, h256 const& _codeHash, unsigned _depth = 0):
+		ExtVMFace(_myAddress, _caller, _origin, _value, _gasPrice, _data, _code.toBytes(), _codeHash, _s.m_previousBlock, _s.m_currentBlock, _lh, _depth), m_s(_s), m_origCache(_s.m_cache)
 	{
 		m_s.ensureCached(_myAddress, true, true);
 	}
diff --git a/libethereum/State.cpp b/libethereum/State.cpp
index f40574fde..d694e78f1 100644
--- a/libethereum/State.cpp
+++ b/libethereum/State.cpp
@@ -141,7 +141,7 @@ State::State(OverlayDB const& _db, BlockChain const& _bc, h256 _h, ImportRequire
 
 		// 2. Enact the block's transactions onto this state.
 		m_ourAddress = bi.coinbaseAddress;
-		enact(&b, _bc, _ir);
+		enact(BlockChain::verifyBlock(b, _ir), _bc, _ir);
 	}
 	else
 	{
@@ -382,7 +382,7 @@ bool State::sync(BlockChain const& _bc, h256 _block, BlockInfo const& _bi, Impor
 	return ret;
 }
 
-u256 State::enactOn(bytesConstRef _block, BlockInfo const& _bi, BlockChain const& _bc, ImportRequirements::value _ir)
+u256 State::enactOn(VerifiedBlockRef const& _block, BlockChain const& _bc, ImportRequirements::value _ir)
 {
 #if ETH_TIMED_ENACTMENTS
 	boost::timer t;
@@ -393,8 +393,8 @@ u256 State::enactOn(bytesConstRef _block, BlockInfo const& _bi, BlockChain const
 #endif
 
 	// Check family:
-	BlockInfo biParent = _bc.info(_bi.parentHash);
-	_bi.verifyParent(biParent);
+	BlockInfo biParent = _bc.info(_block.info.parentHash);
+	_block.info.verifyParent(biParent);
 
 #if ETH_TIMED_ENACTMENTS
 	populateVerify = t.elapsed();
@@ -410,7 +410,7 @@ u256 State::enactOn(bytesConstRef _block, BlockInfo const& _bi, BlockChain const
 	t.restart();
 #endif
 
-	sync(_bc, _bi.parentHash, BlockInfo(), _ir);
+	sync(_bc, _block.info.parentHash, BlockInfo(), _ir);
 	resetCurrent();
 
 #if ETH_TIMED_ENACTMENTS
@@ -592,15 +592,12 @@ string State::vmTrace(bytesConstRef _block, BlockChain const& _bc, ImportRequire
 	return ss.str();
 }
 
-u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirements::value _ir)
+u256 State::enact(VerifiedBlockRef const& _block, BlockChain const& _bc, ImportRequirements::value _ir)
 {
 	// m_currentBlock is assumed to be prepopulated and reset.
-
-	BlockInfo bi(_block, (_ir & ImportRequirements::ValidNonce) ? CheckEverything : IgnoreNonce);
-
 #if !ETH_RELEASE
-	assert(m_previousBlock.hash() == bi.parentHash);
-	assert(m_currentBlock.parentHash == bi.parentHash);
+	assert(m_previousBlock.hash() == _block.info.parentHash);
+	assert(m_currentBlock.parentHash == _block.info.parentHash);
 	assert(rootHash() == m_previousBlock.stateRoot);
 #endif
 
@@ -608,32 +605,31 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 		BOOST_THROW_EXCEPTION(InvalidParentHash());
 
 	// Populate m_currentBlock with the correct values.
-	m_currentBlock = bi;
-	m_currentBlock.verifyInternals(_block);
+	m_currentBlock = _block.info;
 	m_currentBlock.noteDirty();
 
 //	cnote << "playback begins:" << m_state.root();
 //	cnote << m_state;
 
 	LastHashes lh = _bc.lastHashes((unsigned)m_previousBlock.number);
-	RLP rlp(_block);
+	RLP rlp(_block.block);
 
 	vector<bytes> receipts;
 
 	// All ok with the block generally. Play back the transactions now...
 	unsigned i = 0;
-	for (auto const& tr: rlp[1])
+	for (auto const& tr: _block.transactions)
 	{
 		try {
 			LogOverride<ExecutiveWarnChannel> o(false);
-			execute(lh, Transaction(tr.data(), CheckTransaction::Everything));
+			execute(lh, tr);
 		}
 		catch (...)
 		{
-			badBlock(_block, "Invalid transaction");
+			badBlock(_block.block, "Invalid transaction");
 			cwarn << "  Transaction Index:" << i;
 			LogOverride<ExecutiveWarnChannel> o(true);
-			execute(lh, Transaction(tr.data(), CheckTransaction::Everything));
+			execute(lh, tr);
 			throw;
 		}
 
@@ -646,7 +642,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 	auto receiptsRoot = orderedTrieRoot(receipts);
 	if (receiptsRoot != m_currentBlock.receiptsRoot)
 	{
-		badBlock(_block, "Bad receipts state root");
+		badBlock(_block.block, "Bad receipts state root");
 		cwarn << "  Received: " << toString(m_currentBlock.receiptsRoot);
 		cwarn << "  Expected: " << toString(receiptsRoot) << " which is:";
 		for (unsigned j = 0; j < i; ++j)
@@ -657,13 +653,13 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 			cwarn << "    Hex: " << toHex(b);
 			cwarn << "    " << TransactionReceipt(&b);
 		}
-		cwarn << "  VMTrace:\n" << vmTrace(_block, _bc, _ir);
+		cwarn << "  VMTrace:\n" << vmTrace(_block.block, _bc, _ir);
 		BOOST_THROW_EXCEPTION(InvalidReceiptsStateRoot());
 	}
 
 	if (m_currentBlock.logBloom != logBloom())
 	{
-		badBlock(_block, "Bad log bloom");
+		badBlock(_block.block, "Bad log bloom");
 		cwarn << "  Receipt blooms:";
 		for (unsigned j = 0; j < i; ++j)
 		{
@@ -680,7 +676,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 	// Check uncles & apply their rewards to state.
 	if (rlp[2].itemCount() > 2)
 	{
-		badBlock(_block, "Too many uncles");
+		badBlock(_block.block, "Too many uncles");
 		BOOST_THROW_EXCEPTION(TooManyUncles());
 	}
 
@@ -693,7 +689,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 		auto h = sha3(i.data());
 		if (excluded.count(h))
 		{
-			badBlock(_block, "Invalid uncle included");
+			badBlock(_block.block, "Invalid uncle included");
 			BOOST_THROW_EXCEPTION(UncleInChain() << errinfo_comment("Uncle in block already mentioned") << errinfo_data(toString(excluded)) << errinfo_hash256(sha3(i.data())));
 		}
 		excluded.insert(h);
@@ -702,7 +698,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 		BlockInfo uncleParent(_bc.block(uncle.parentHash));
 		if ((bigint)uncleParent.number < (bigint)m_currentBlock.number - 7)
 		{
-			badBlock(_block, "Uncle too old");
+			badBlock(_block.block, "Uncle too old");
 			cwarn << "  Uncle number: " << uncle.number;
 			cwarn << "  Uncle parent number: " << uncleParent.number;
 			cwarn << "  Block number: " << m_currentBlock.number;
@@ -710,7 +706,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 		}
 		else if (uncle.number == m_currentBlock.number)
 		{
-			badBlock(_block, "Uncle is brother");
+			badBlock(_block.block, "Uncle is brother");
 			cwarn << "  Uncle number: " << uncle.number;
 			cwarn << "  Uncle parent number: " << uncleParent.number;
 			cwarn << "  Block number: " << m_currentBlock.number;
@@ -730,12 +726,12 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 	// Hash the state trie and check against the state_root hash in m_currentBlock.
 	if (m_currentBlock.stateRoot != m_previousBlock.stateRoot && m_currentBlock.stateRoot != rootHash())
 	{
-		badBlock(_block, "Bad state root");
+		badBlock(_block.block, "Bad state root");
 		cnote << "  Given to be:" << m_currentBlock.stateRoot;
 		// TODO: Fix
 //		cnote << SecureTrieDB<Address, OverlayDB>(&m_db, m_currentBlock.stateRoot);
 		cnote << "  Calculated to be:" << rootHash();
-		cwarn << "  VMTrace:\n" << vmTrace(_block, _bc, _ir);
+		cwarn << "  VMTrace:\n" << vmTrace(_block.block, _bc, _ir);
 //		cnote << m_state;
 		// Rollback the trie.
 		m_db.rollback();
@@ -745,7 +741,7 @@ u256 State::enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirement
 	if (m_currentBlock.gasUsed != gasUsed())
 	{
 		// Rollback the trie.
-		badBlock(_block, "Invalid gas used");
+		badBlock(_block.block, "Invalid gas used");
 		m_db.rollback();
 		BOOST_THROW_EXCEPTION(InvalidGasUsed() << RequirementError(bigint(gasUsed()), bigint(m_currentBlock.gasUsed)));
 	}
@@ -823,7 +819,7 @@ bool State::amIJustParanoid(BlockChain const& _bc)
 		cnote << "PARANOIA root:" << s.rootHash();
 //		s.m_currentBlock.populate(&block.out(), false);
 //		s.m_currentBlock.verifyInternals(&block.out());
-		s.enact(&block.out(), _bc, false);	// don't check nonce for this since we haven't mined it yet.
+		s.enact(BlockChain::verifyBlock(block.out()), _bc, false);	// don't check nonce for this since we haven't mined it yet.
 		s.cleanup(false);
 		return true;
 	}
@@ -1122,6 +1118,8 @@ h256 State::codeHash(Address _contract) const
 {
 	if (!addressHasCode(_contract))
 		return EmptySHA3;
+	if (m_cache[_contract].isFreshCode())
+		return sha3(code(_contract));
 	return m_cache[_contract].codeHash();
 }
 
diff --git a/libethereum/State.h b/libethereum/State.h
index 55d5cfb4c..c4403b41b 100644
--- a/libethereum/State.h
+++ b/libethereum/State.h
@@ -48,6 +48,7 @@ namespace eth
 
 class BlockChain;
 class State;
+struct VerifiedBlockRef;
 
 struct StateChat: public LogChannel { static const char* name(); static const int verbosity = 4; };
 struct StateTrace: public LogChannel { static const char* name(); static const int verbosity = 5; };
@@ -308,7 +309,7 @@ public:
 
 	/// Execute all transactions within a given block.
 	/// @returns the additional total difficulty.
-	u256 enactOn(bytesConstRef _block, BlockInfo const& _bi, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);
+	u256 enactOn(VerifiedBlockRef const& _block, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);
 
 	/// Returns back to a pristine state after having done a playback.
 	/// @arg _fullCommit if true flush everything out to disk. If false, this effectively only validates
@@ -349,7 +350,7 @@ private:
 
 	/// Execute the given block, assuming it corresponds to m_currentBlock.
 	/// Throws on failure.
-	u256 enact(bytesConstRef _block, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);
+	u256 enact(VerifiedBlockRef const& _block, BlockChain const& _bc, ImportRequirements::value _ir = ImportRequirements::Default);
 
 	/// Finalise the block, applying the earned rewards.
 	void applyRewards(std::vector<BlockInfo> const& _uncleBlockHeaders);
diff --git a/libethereum/VerifiedBlock.h b/libethereum/VerifiedBlock.h
new file mode 100644
index 000000000..ddd808901
--- /dev/null
+++ b/libethereum/VerifiedBlock.h
@@ -0,0 +1,53 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	cpp-ethereum is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file VerfiedBlock.h
+ * @author Gav Wood <i@gavwood.com>
+ * @date 2014
+ */
+
+
+#include <libdevcore/Common.h>
+#include <libethcore/BlockInfo.h>
+
+#pragma once
+
+namespace dev
+{
+namespace eth
+{
+
+class Transaction;
+
+/// @brief Verified block info, does not hold block data, but a reference instead
+struct VerifiedBlockRef
+{
+	bytesConstRef block; 					///<  Block data reference
+	BlockInfo info;							///< Prepopulated block info
+	std::vector<Transaction> transactions;	///< Verified list of block transactions
+};
+
+/// @brief Verified block info, combines block data and verified info/transactions
+struct VerifiedBlock
+{
+	VerifiedBlockRef verified;				///< Verified block structures
+	bytes blockData;						///< Block data
+};
+
+using VerifiedBlocks = std::vector<VerifiedBlock>;
+
+}
+}
diff --git a/libevm/ExtVMFace.cpp b/libevm/ExtVMFace.cpp
index ebef1fdb0..ad419d2a3 100644
--- a/libevm/ExtVMFace.cpp
+++ b/libevm/ExtVMFace.cpp
@@ -25,7 +25,7 @@ using namespace std;
 using namespace dev;
 using namespace dev::eth;
 
-ExtVMFace::ExtVMFace(Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytes const& _code, BlockInfo const& _previousBlock, BlockInfo const& _currentBlock, LastHashes const& _lh, unsigned _depth):
+ExtVMFace::ExtVMFace(Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytes const& _code, h256 const& _codeHash, BlockInfo const& _previousBlock, BlockInfo const& _currentBlock, LastHashes const& _lh, unsigned _depth):
 	myAddress(_myAddress),
 	caller(_caller),
 	origin(_origin),
@@ -33,6 +33,7 @@ ExtVMFace::ExtVMFace(Address _myAddress, Address _caller, Address _origin, u256
 	gasPrice(_gasPrice),
 	data(_data),
 	code(_code),
+	codeHash(_codeHash),
 	lastHashes(_lh),
 	previousBlock(_previousBlock),
 	currentBlock(_currentBlock),
diff --git a/libevm/ExtVMFace.h b/libevm/ExtVMFace.h
index 6b35094bb..bb102bef3 100644
--- a/libevm/ExtVMFace.h
+++ b/libevm/ExtVMFace.h
@@ -130,7 +130,7 @@ public:
 	ExtVMFace() = default;
 
 	/// Full constructor.
-	ExtVMFace(Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytes const& _code, BlockInfo const& _previousBlock, BlockInfo const& _currentBlock, LastHashes const& _lh, unsigned _depth);
+	ExtVMFace(Address _myAddress, Address _caller, Address _origin, u256 _value, u256 _gasPrice, bytesConstRef _data, bytes const& _code, h256 const& _codeHash, BlockInfo const& _previousBlock, BlockInfo const& _currentBlock, LastHashes const& _lh, unsigned _depth);
 
 	virtual ~ExtVMFace() = default;
 
@@ -186,6 +186,7 @@ public:
 	u256 gasPrice;				///< Price of gas (that we already paid).
 	bytesConstRef data;			///< Current input data.
 	bytes code;					///< Current code that is executing.
+	h256 codeHash;				///< SHA3 hash of the executing code
 	LastHashes lastHashes;		///< Most recent 256 blocks' hashes.
 	BlockInfo previousBlock;	///< The previous block's information.	TODO: PoC-8: REMOVE
 	BlockInfo currentBlock;		///< The current block's information.
diff --git a/libp2p/RLPxFrameIO.h b/libp2p/RLPxFrameIO.h
index 0f0504e48..9d4c274be 100644
--- a/libp2p/RLPxFrameIO.h
+++ b/libp2p/RLPxFrameIO.h
@@ -56,7 +56,7 @@ public:
 	
 	bool isConnected() const { return m_socket.is_open(); }
 	void close() { try { boost::system::error_code ec; m_socket.shutdown(bi::tcp::socket::shutdown_both, ec); if (m_socket.is_open()) m_socket.close(); } catch (...){} }
-	bi::tcp::endpoint remoteEndpoint() { try { return m_socket.remote_endpoint(); } catch (...){ return bi::tcp::endpoint(); } }
+	bi::tcp::endpoint remoteEndpoint() { boost::system::error_code ec; return m_socket.remote_endpoint(ec); }
 	bi::tcp::socket& ref() { return m_socket; }
 	
 protected:
@@ -130,4 +130,4 @@ private:
 };
 
 }
-}
\ No newline at end of file
+}
diff --git a/test/libevm/vm.cpp b/test/libevm/vm.cpp
index d52c650f9..ec66837e1 100644
--- a/test/libevm/vm.cpp
+++ b/test/libevm/vm.cpp
@@ -33,7 +33,7 @@ using namespace dev::eth;
 using namespace dev::test;
 
 FakeExtVM::FakeExtVM(eth::BlockInfo const& _previousBlock, eth::BlockInfo const& _currentBlock, unsigned _depth):			/// TODO: XXX: remove the default argument & fix.
-	ExtVMFace(Address(), Address(), Address(), 0, 1, bytesConstRef(), bytes(), _previousBlock, _currentBlock, test::lastHashes(_currentBlock.number), _depth) {}
+	ExtVMFace(Address(), Address(), Address(), 0, 1, bytesConstRef(), bytes(), EmptySHA3, _previousBlock, _currentBlock, test::lastHashes(_currentBlock.number), _depth) {}
 
 h160 FakeExtVM::create(u256 _endowment, u256& io_gas, bytesConstRef _init, OnOpFunc const&)
 {