diff --git a/Cargo.lock b/Cargo.lock
index 9ce1c4372..0003098a8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -215,11 +215,13 @@ name = "ethcore-rpc"
 version = "0.9.99"
 dependencies = [
  "clippy 0.0.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ethash 0.9.99",
  "ethcore 0.9.99",
  "ethcore-util 0.9.99",
  "ethsync 0.9.99",
  "jsonrpc-core 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "jsonrpc-http-server 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.18 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_codegen 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/ethash/src/compute.rs b/ethash/src/compute.rs
index 6c311993b..eb64151d0 100644
--- a/ethash/src/compute.rs
+++ b/ethash/src/compute.rs
@@ -172,7 +172,8 @@ fn get_data_size(block_number: u64) -> usize {
 }
 
 #[inline]
-fn get_seedhash(block_number: u64) -> H256 {
+/// Given the `block_number`, determine the seed hash for Ethash.
+pub fn get_seedhash(block_number: u64) -> H256 {
 	let epochs = block_number / ETHASH_EPOCH_LENGTH;
 	let mut ret: H256 = [0u8; 32];
 	for _ in 0..epochs {
diff --git a/ethash/src/lib.rs b/ethash/src/lib.rs
index e96b98b81..982f7129b 100644
--- a/ethash/src/lib.rs
+++ b/ethash/src/lib.rs
@@ -24,7 +24,7 @@ mod compute;
 
 use std::mem;
 use compute::Light;
-pub use compute::{quick_get_difficulty, H256, ProofOfWork, ETHASH_EPOCH_LENGTH};
+pub use compute::{get_seedhash, quick_get_difficulty, H256, ProofOfWork, ETHASH_EPOCH_LENGTH};
 
 use std::sync::{Arc, Mutex};
 
@@ -35,7 +35,7 @@ struct LightCache {
 	prev: Option<Arc<Light>>,
 }
 
-/// Lighy/Full cache manager
+/// Light/Full cache manager.
 pub struct EthashManager {
 	cache: Mutex<LightCache>,
 }
diff --git a/ethcore/res/ethereum/tests b/ethcore/res/ethereum/tests
index f32954b3d..99afe8f5a 160000
--- a/ethcore/res/ethereum/tests
+++ b/ethcore/res/ethereum/tests
@@ -1 +1 @@
-Subproject commit f32954b3ddb5af2dc3dc9ec6d9a28bee848fdf70
+Subproject commit 99afe8f5aad7bca5d0f1b1685390a4dea32d73c3
diff --git a/ethcore/src/block.rs b/ethcore/src/block.rs
index 70c6c2fb2..f5788baba 100644
--- a/ethcore/src/block.rs
+++ b/ethcore/src/block.rs
@@ -21,7 +21,7 @@
 use common::*;
 use engine::*;
 use state::*;
-use verification::PreVerifiedBlock;
+use verification::PreverifiedBlock;
 
 /// A block, encoded as it is on the block chain.
 // TODO: rename to Block
@@ -155,9 +155,9 @@ pub struct OpenBlock<'x> {
 /// Just like OpenBlock, except that we've applied `Engine::on_close_block`, finished up the non-seal header fields,
 /// and collected the uncles.
 ///
-/// There is no function available to push a transaction. If you want that you'll need to `reopen()` it.
-pub struct ClosedBlock<'x> {
-	open_block: OpenBlock<'x>,
+/// There is no function available to push a transaction.
+pub struct ClosedBlock {
+	block: ExecutedBlock,
 	uncle_bytes: Bytes,
 }
 
@@ -178,10 +178,12 @@ impl<'x> OpenBlock<'x> {
 			last_hashes: last_hashes,
 		};
 
-		r.block.base.header.set_number(parent.number() + 1);
-		r.block.base.header.set_author(author);
-		r.block.base.header.set_extra_data(extra_data);
-		r.block.base.header.set_timestamp_now();
+		r.block.base.header.parent_hash = parent.hash();
+		r.block.base.header.number = parent.number + 1;
+		r.block.base.header.author = author;
+		r.block.base.header.set_timestamp_now(parent.timestamp());
+		r.block.base.header.extra_data = extra_data;
+		r.block.base.header.note_dirty();
 
 		engine.populate_from_parent(&mut r.block.base.header, parent);
 		engine.on_new_block(&mut r.block);
@@ -259,7 +261,7 @@ impl<'x> OpenBlock<'x> {
 	}
 
 	/// Turn this into a `ClosedBlock`. A BlockChain must be provided in order to figure out the uncles.
-	pub fn close(self) -> ClosedBlock<'x> {
+	pub fn close(self) -> ClosedBlock {
 		let mut s = self;
 		s.engine.on_close_block(&mut s.block);
 		s.block.base.header.transactions_root = ordered_trie_root(s.block.base.transactions.iter().map(|ref e| e.rlp_bytes().to_vec()).collect());
@@ -271,7 +273,10 @@ impl<'x> OpenBlock<'x> {
 		s.block.base.header.gas_used = s.block.receipts.last().map_or(U256::zero(), |r| r.gas_used);
 		s.block.base.header.note_dirty();
 
-		ClosedBlock::new(s, uncle_bytes)
+		ClosedBlock {
+			block: s.block, 
+			uncle_bytes: uncle_bytes,
+		}
 	}
 }
 
@@ -279,38 +284,40 @@ impl<'x> IsBlock for OpenBlock<'x> {
 	fn block(&self) -> &ExecutedBlock { &self.block }
 }
 
-impl<'x> IsBlock for ClosedBlock<'x> {
-	fn block(&self) -> &ExecutedBlock { &self.open_block.block }
+impl<'x> IsBlock for ClosedBlock {
+	fn block(&self) -> &ExecutedBlock { &self.block }
 }
 
-impl<'x> ClosedBlock<'x> {
-	fn new(open_block: OpenBlock<'x>, uncle_bytes: Bytes) -> Self {
-		ClosedBlock {
-			open_block: open_block,
-			uncle_bytes: uncle_bytes,
-		}
-	}
-
+impl ClosedBlock {
 	/// Get the hash of the header without seal arguments.
 	pub fn hash(&self) -> H256 { self.header().rlp_sha3(Seal::Without) }
 
 	/// Provide a valid seal in order to turn this into a `SealedBlock`.
 	///
 	/// NOTE: This does not check the validity of `seal` with the engine.
-	pub fn seal(self, seal: Vec<Bytes>) -> Result<SealedBlock, BlockError> {
+	pub fn seal(self, engine: &Engine, seal: Vec<Bytes>) -> Result<SealedBlock, BlockError> {
 		let mut s = self;
-		if seal.len() != s.open_block.engine.seal_fields() {
-			return Err(BlockError::InvalidSealArity(Mismatch{expected: s.open_block.engine.seal_fields(), found: seal.len()}));
+		if seal.len() != engine.seal_fields() {
+			return Err(BlockError::InvalidSealArity(Mismatch{expected: engine.seal_fields(), found: seal.len()}));
 		}
-		s.open_block.block.base.header.set_seal(seal);
-		Ok(SealedBlock { block: s.open_block.block, uncle_bytes: s.uncle_bytes })
+		s.block.base.header.set_seal(seal);
+		Ok(SealedBlock { block: s.block, uncle_bytes: s.uncle_bytes })
 	}
 
-	/// Turn this back into an `OpenBlock`.
-	pub fn reopen(self) -> OpenBlock<'x> { self.open_block }
+	/// Provide a valid seal in order to turn this into a `SealedBlock`.
+	/// This does check the validity of `seal` with the engine.
+	/// Returns the `ClosedBlock` back again if the seal is no good.
+	pub fn try_seal(self, engine: &Engine, seal: Vec<Bytes>) -> Result<SealedBlock, ClosedBlock> {
+		let mut s = self;
+		s.block.base.header.set_seal(seal);
+		match engine.verify_block_seal(&s.block.base.header) {
+			Err(_) => Err(s),
+			_ => Ok(SealedBlock { block: s.block, uncle_bytes: s.uncle_bytes }),
+		}
+	}
 
 	/// Drop this object and return the underlieing database.
-	pub fn drain(self) -> JournalDB { self.open_block.block.state.drop().1 }
+	pub fn drain(self) -> JournalDB { self.block.state.drop().1 }
 }
 
 impl SealedBlock {
@@ -332,7 +339,7 @@ impl IsBlock for SealedBlock {
 }
 
 /// Enact the block given by block header, transactions and uncles
-pub fn enact<'x>(header: &Header, transactions: &[SignedTransaction], uncles: &[Header], engine: &'x Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock<'x>, Error> {
+pub fn enact(header: &Header, transactions: &[SignedTransaction], uncles: &[Header], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	{
 		if ::log::max_log_level() >= ::log::LogLevel::Trace {
 			let s = State::from_existing(db.clone(), parent.state_root().clone(), engine.account_start_nonce());
@@ -350,14 +357,14 @@ pub fn enact<'x>(header: &Header, transactions: &[SignedTransaction], uncles: &[
 }
 
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
-pub fn enact_bytes<'x>(block_bytes: &[u8], engine: &'x Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock<'x>, Error> {
+pub fn enact_bytes(block_bytes: &[u8], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	let block = BlockView::new(block_bytes);
 	let header = block.header();
 	enact(&header, &block.transactions(), &block.uncles(), engine, db, parent, last_hashes)
 }
 
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
-pub fn enact_verified<'x>(block: &PreVerifiedBlock, engine: &'x Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock<'x>, Error> {
+pub fn enact_verified(block: &PreverifiedBlock, engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<ClosedBlock, Error> {
 	let view = BlockView::new(&block.bytes);
 	enact(&block.header, &block.transactions, &view.uncles(), engine, db, parent, last_hashes)
 }
@@ -365,7 +372,7 @@ pub fn enact_verified<'x>(block: &PreVerifiedBlock, engine: &'x Engine, db: Jour
 /// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header. Seal the block aferwards
 pub fn enact_and_seal(block_bytes: &[u8], engine: &Engine, db: JournalDB, parent: &Header, last_hashes: LastHashes) -> Result<SealedBlock, Error> {
 	let header = BlockView::new(block_bytes).header_view();
-	Ok(try!(try!(enact_bytes(block_bytes, engine, db, parent, last_hashes)).seal(header.seal())))
+	Ok(try!(try!(enact_bytes(block_bytes, engine, db, parent, last_hashes)).seal(engine, header.seal())))
 }
 
 #[cfg(test)]
@@ -386,7 +393,7 @@ mod tests {
 		let last_hashes = vec![genesis_header.hash()];
 		let b = OpenBlock::new(engine.deref(), db, &genesis_header, last_hashes, Address::zero(), vec![]);
 		let b = b.close();
-		let _ = b.seal(vec![]);
+		let _ = b.seal(engine.deref(), vec![]);
 	}
 
 	#[test]
@@ -398,7 +405,7 @@ mod tests {
 		let mut db_result = get_temp_journal_db();
 		let mut db = db_result.take();
 		engine.spec().ensure_db_good(&mut db);
-		let b = OpenBlock::new(engine.deref(), db, &genesis_header, vec![genesis_header.hash()], Address::zero(), vec![]).close().seal(vec![]).unwrap();
+		let b = OpenBlock::new(engine.deref(), db, &genesis_header, vec![genesis_header.hash()], Address::zero(), vec![]).close().seal(engine.deref(), vec![]).unwrap();
 		let orig_bytes = b.rlp_bytes();
 		let orig_db = b.drain();
 
diff --git a/ethcore/src/block_queue.rs b/ethcore/src/block_queue.rs
index 668c004e5..490a17995 100644
--- a/ethcore/src/block_queue.rs
+++ b/ethcore/src/block_queue.rs
@@ -28,7 +28,7 @@ use service::*;
 use client::BlockStatus;
 use util::panics::*;
 
-known_heap_size!(0, UnVerifiedBlock, VerifyingBlock, PreVerifiedBlock);
+known_heap_size!(0, UnverifiedBlock, VerifyingBlock, PreverifiedBlock);
 
 const MIN_MEM_LIMIT: usize = 16384;
 const MIN_QUEUE_LIMIT: usize = 512;
@@ -105,14 +105,14 @@ pub struct BlockQueue {
 	max_mem_use: usize,
 }
 
-struct UnVerifiedBlock {
+struct UnverifiedBlock {
 	header: Header,
 	bytes: Bytes,
 }
 
 struct VerifyingBlock {
 	hash: H256,
-	block: Option<PreVerifiedBlock>,
+	block: Option<PreverifiedBlock>,
 }
 
 struct QueueSignal {
@@ -134,8 +134,8 @@ impl QueueSignal {
 
 #[derive(Default)]
 struct Verification {
-	unverified: VecDeque<UnVerifiedBlock>,
-	verified: VecDeque<PreVerifiedBlock>,
+	unverified: VecDeque<UnverifiedBlock>,
+	verified: VecDeque<PreverifiedBlock>,
 	verifying: VecDeque<VerifyingBlock>,
 	bad: HashSet<H256>,
 }
@@ -244,7 +244,7 @@ impl BlockQueue {
 		}
 	}
 
-	fn drain_verifying(verifying: &mut VecDeque<VerifyingBlock>, verified: &mut VecDeque<PreVerifiedBlock>, bad: &mut HashSet<H256>) {
+	fn drain_verifying(verifying: &mut VecDeque<VerifyingBlock>, verified: &mut VecDeque<PreverifiedBlock>, bad: &mut HashSet<H256>) {
 		while !verifying.is_empty() && verifying.front().unwrap().block.is_some() {
 			let block = verifying.pop_front().unwrap().block.unwrap();
 			if bad.contains(&block.header.parent_hash) {
@@ -289,31 +289,31 @@ impl BlockQueue {
 		let header = BlockView::new(&bytes).header();
 		let h = header.hash();
 		if self.processing.read().unwrap().contains(&h) {
-			return Err(ImportError::AlreadyQueued);
+			return Err(x!(ImportError::AlreadyQueued));
 		}
 		{
 			let mut verification = self.verification.lock().unwrap();
 			if verification.bad.contains(&h) {
-				return Err(ImportError::Bad(None));
+				return Err(x!(ImportError::KnownBad));
 			}
 
 			if verification.bad.contains(&header.parent_hash) {
 				verification.bad.insert(h.clone());
-				return Err(ImportError::Bad(None));
+				return Err(x!(ImportError::KnownBad));
 			}
 		}
 
 		match verify_block_basic(&header, &bytes, self.engine.deref().deref()) {
 			Ok(()) => {
 				self.processing.write().unwrap().insert(h.clone());
-				self.verification.lock().unwrap().unverified.push_back(UnVerifiedBlock { header: header, bytes: bytes });
+				self.verification.lock().unwrap().unverified.push_back(UnverifiedBlock { header: header, bytes: bytes });
 				self.more_to_verify.notify_all();
 				Ok(h)
 			},
 			Err(err) => {
 				warn!(target: "client", "Stage 1 block verification failed for {}\nError: {:?}", BlockView::new(&bytes).header_view().sha3(), err);
 				self.verification.lock().unwrap().bad.insert(h.clone());
-				Err(From::from(err))
+				Err(err)
 			}
 		}
 	}
@@ -352,7 +352,7 @@ impl BlockQueue {
 	}
 
 	/// Removes up to `max` verified blocks from the queue
-	pub fn drain(&mut self, max: usize) -> Vec<PreVerifiedBlock> {
+	pub fn drain(&mut self, max: usize) -> Vec<PreverifiedBlock> {
 		let mut verification = self.verification.lock().unwrap();
 		let count = min(max, verification.verified.len());
 		let mut result = Vec::with_capacity(count);
@@ -455,7 +455,7 @@ mod tests {
 		match duplicate_import {
 			Err(e) => {
 				match e {
-					ImportError::AlreadyQueued => {},
+					Error::Import(ImportError::AlreadyQueued) => {},
 					_ => { panic!("must return AlreadyQueued error"); }
 				}
 			}
diff --git a/ethcore/src/blockchain/blockchain.rs b/ethcore/src/blockchain/blockchain.rs
index 10e844192..185bcaad3 100644
--- a/ethcore/src/blockchain/blockchain.rs
+++ b/ethcore/src/blockchain/blockchain.rs
@@ -473,6 +473,12 @@ impl BlockChain {
 		self.extras_db.write(batch).unwrap();
 	}
 
+	/// Given a block's `parent`, find every block header which represents a valid uncle.
+	pub fn find_uncle_headers(&self, _parent: &H256) -> Vec<Header> {
+		// TODO
+		Vec::new()
+	}
+
 	/// Get inserted block info which is critical to preapre extras updates.
 	fn block_info(&self, block_bytes: &[u8]) -> BlockInfo {
 		let block = BlockView::new(block_bytes);
diff --git a/ethcore/src/chainfilter/chainfilter.rs b/ethcore/src/chainfilter/chainfilter.rs
index fb6df877a..387d750fd 100644
--- a/ethcore/src/chainfilter/chainfilter.rs
+++ b/ethcore/src/chainfilter/chainfilter.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Multilevel blockchain bloom filter.
-//! 
+//!
 //! ```not_run
 //! extern crate ethcore_util as util;
 //! extern crate ethcore;
@@ -23,33 +23,33 @@
 //! use util::sha3::*;
 //! use util::hash::*;
 //! use ethcore::chainfilter::*;
-//! 
+//!
 //! fn main() {
 //!		let (index_size, bloom_levels) = (16, 3);
 //!		let mut cache = MemoryCache::new();
-//!		
+//!
 //!		let address = Address::from_str("ef2d6d194084c2de36e0dabfce45d046b37d1106").unwrap();
-//!		
+//!
 //!		// borrow cache for reading inside the scope
 //!		let modified_blooms = {
-//!			let filter = ChainFilter::new(&cache, index_size, bloom_levels);	
+//!			let filter = ChainFilter::new(&cache, index_size, bloom_levels);
 //!			let block_number = 39;
 //!			let mut bloom = H2048::new();
 //!			bloom.shift_bloomed(&address.sha3());
 //!			filter.add_bloom(&bloom, block_number)
 //!		};
-//!		
+//!
 //!		// number of updated blooms is equal number of levels
 //!		assert_eq!(modified_blooms.len(), bloom_levels as usize);
 //!
 //!		// lets inserts modified blooms into the cache
 //!		cache.insert_blooms(modified_blooms);
-//!		
+//!
 //!		// borrow cache for another reading operations
 //!		{
-//!			let filter = ChainFilter::new(&cache, index_size, bloom_levels);	
+//!			let filter = ChainFilter::new(&cache, index_size, bloom_levels);
 //!			let blocks = filter.blocks_with_address(&address, 10, 40);
-//!			assert_eq!(blocks.len(), 1);	
+//!			assert_eq!(blocks.len(), 1);
 //!			assert_eq!(blocks[0], 39);
 //!		}
 //! }
@@ -71,7 +71,7 @@ pub struct ChainFilter<'a, D>
 impl<'a, D> ChainFilter<'a, D> where D: FilterDataSource
 {
 	/// Creates new filter instance.
-	/// 
+	///
 	/// Borrows `FilterDataSource` for reading.
 	pub fn new(data_source: &'a D, index_size: usize, levels: u8) -> Self {
 		ChainFilter {
@@ -88,7 +88,7 @@ impl<'a, D> ChainFilter<'a, D> where D: FilterDataSource
 			None => return None,
 			Some(level_bloom) => match level {
 				// if we are on the lowest level
-				0 => return match offset < to_block {
+				0 => return match offset <= to_block {
 					// take the value if its smaller than to_block
 					true if level_bloom.contains(bloom) => Some(vec![offset]),
 					// return None if it is is equal to to_block
@@ -153,7 +153,7 @@ impl<'a, D> ChainFilter<'a, D> where D: FilterDataSource
 			for i in 0..blooms.len() {
 
 				let index = self.indexer.bloom_index(block_number + i, level);
-				let new_bloom = {	
+				let new_bloom = {
 					// use new blooms before db blooms where necessary
 					let bloom_at = | index | { result.get(&index).cloned().or_else(|| self.data_source.bloom_at_index(&index)) };
 
diff --git a/ethcore/src/chainfilter/tests.rs b/ethcore/src/chainfilter/tests.rs
index 2baa93e55..08af44720 100644
--- a/ethcore/src/chainfilter/tests.rs
+++ b/ethcore/src/chainfilter/tests.rs
@@ -22,7 +22,7 @@ use util::sha3::*;
 use chainfilter::{BloomIndex, FilterDataSource, ChainFilter};
 
 /// In memory cache for blooms.
-/// 
+///
 /// Stores all blooms in HashMap, which indexes them by `BloomIndex`.
 pub struct MemoryCache {
 	blooms: HashMap<BloomIndex, H2048>,
@@ -35,7 +35,7 @@ impl MemoryCache {
 	}
 
 	/// inserts all blooms into cache
-	/// 
+	///
 	/// if bloom at given index already exists, overwrites it
 	pub fn insert_blooms(&mut self, blooms: HashMap<BloomIndex, H2048>) {
 		self.blooms.extend(blooms);
@@ -81,13 +81,13 @@ fn test_topic_basic_search() {
 
 	{
 		let filter = ChainFilter::new(&cache, index_size, bloom_levels);
-		let blocks = filter.blocks_with_bloom(&to_bloom(&topic), 0, 23);
+		let blocks = filter.blocks_with_bloom(&to_bloom(&topic), 0, 22);
 		assert_eq!(blocks.len(), 0);
 	}
 
 	{
 		let filter = ChainFilter::new(&cache, index_size, bloom_levels);
-		let blocks = filter.blocks_with_bloom(&to_bloom(&topic), 23, 24);
+		let blocks = filter.blocks_with_bloom(&to_bloom(&topic), 23, 23);
 		assert_eq!(blocks.len(), 1);
 		assert_eq!(blocks[0], 23);
 	}
@@ -144,7 +144,7 @@ fn test_reset_chain_head_simple() {
 
 	cache.insert_blooms(modified_blooms_3);
 
-	
+
 	let reset_modified_blooms = {
 		let filter = ChainFilter::new(&cache, index_size, bloom_levels);
 		filter.reset_chain_head(&[to_bloom(&topic_4), to_bloom(&topic_5)], 15, 17)
@@ -183,7 +183,7 @@ fn for_each_bloom<F>(bytes: &[u8], mut f: F) where F: FnMut(usize, &H2048) {
 }
 
 fn for_each_log<F>(bytes: &[u8], mut f: F) where F: FnMut(usize, &Address, &[H256]) {
-	let mut reader = BufReader::new(bytes);	
+	let mut reader = BufReader::new(bytes);
 	let mut line = String::new();
 	while reader.read_line(&mut line).unwrap() > 0 {
 		{
@@ -235,11 +235,11 @@ fn test_chainfilter_real_data_short_searches() {
 	for_each_log(include_bytes!("logs.txt"), | block_number, address, topics | {
 		println!("block_number: {:?}", block_number);
 		let filter = ChainFilter::new(&cache, index_size, bloom_levels);
-		let blocks = filter.blocks_with_bloom(&to_bloom(address), block_number, block_number + 1);
+		let blocks = filter.blocks_with_bloom(&to_bloom(address), block_number, block_number);
 		assert_eq!(blocks.len(), 1);
 		for (i, topic) in topics.iter().enumerate() {
 			println!("topic: {:?}", i);
-			let blocks = filter.blocks_with_bloom(&to_bloom(topic), block_number, block_number + 1);
+			let blocks = filter.blocks_with_bloom(&to_bloom(topic), block_number, block_number);
 			assert_eq!(blocks.len(), 1);
 		}
 	});
diff --git a/ethcore/src/client.rs b/ethcore/src/client.rs
index f2894decb..4b109c8a3 100644
--- a/ethcore/src/client.rs
+++ b/ethcore/src/client.rs
@@ -21,7 +21,7 @@ use util::panics::*;
 use blockchain::{BlockChain, BlockProvider};
 use views::BlockView;
 use error::*;
-use header::{BlockNumber, Header};
+use header::{BlockNumber};
 use state::State;
 use spec::Spec;
 use engine::Engine;
@@ -176,7 +176,7 @@ pub struct ClientReport {
 
 impl ClientReport {
 	/// Alter internal reporting to reflect the additional `block` has been processed.
-	pub fn accrue_block(&mut self, block: &PreVerifiedBlock) {
+	pub fn accrue_block(&mut self, block: &PreverifiedBlock) {
 		self.blocks_imported += 1;
 		self.transactions_applied += block.transactions.len();
 		self.gas_processed = self.gas_processed + block.header.gas_used;
@@ -193,6 +193,11 @@ pub struct Client {
 	report: RwLock<ClientReport>,
 	import_lock: Mutex<()>,
 	panic_handler: Arc<PanicHandler>,
+
+	// for sealing...
+	sealing_block: Mutex<Option<ClosedBlock>>,
+	author: RwLock<Address>,
+	extra_data: RwLock<Bytes>,
 }
 
 const HISTORY: u64 = 1000;
@@ -228,7 +233,10 @@ impl Client {
 			block_queue: RwLock::new(block_queue),
 			report: RwLock::new(Default::default()),
 			import_lock: Mutex::new(()),
-			panic_handler: panic_handler
+			panic_handler: panic_handler,
+			sealing_block: Mutex::new(None),
+			author: RwLock::new(Address::new()),
+			extra_data: RwLock::new(Vec::new()),
 		}))
 	}
 
@@ -237,10 +245,10 @@ impl Client {
 		self.block_queue.write().unwrap().flush();
 	}
 
-	fn build_last_hashes(&self, header: &Header) -> LastHashes {
+	fn build_last_hashes(&self, parent_hash: H256) -> LastHashes {
 		let mut last_hashes = LastHashes::new();
 		last_hashes.resize(256, H256::new());
-		last_hashes[0] = header.parent_hash.clone();
+		last_hashes[0] = parent_hash;
 		let chain = self.chain.read().unwrap();
 		for i in 0..255 {
 			match chain.block_details(&last_hashes[i]) {
@@ -253,7 +261,7 @@ impl Client {
 		last_hashes
 	}
 
-	fn check_and_close_block(&self, block: &PreVerifiedBlock) -> Result<ClosedBlock, ()> {
+	fn check_and_close_block(&self, block: &PreverifiedBlock) -> Result<ClosedBlock, ()> {
 		let engine = self.engine.deref().deref();
 		let header = &block.header;
 
@@ -273,7 +281,7 @@ impl Client {
 
 		// Enact Verified Block
 		let parent = chain_has_parent.unwrap();
-		let last_hashes = self.build_last_hashes(header);
+		let last_hashes = self.build_last_hashes(header.parent_hash.clone());
 		let db = self.state_db.lock().unwrap().clone();
 
 		let enact_result = enact_verified(&block, engine, db, &parent, last_hashes);
@@ -302,6 +310,8 @@ impl Client {
 		let _import_lock = self.import_lock.lock();
 		let blocks = self.block_queue.write().unwrap().drain(max_blocks_to_import);
 
+		let original_best = self.chain_info().best_block_hash;
+
 		for block in blocks {
 			let header = &block.header;
 
@@ -357,6 +367,10 @@ impl Client {
 			}
 		}
 
+		if self.chain_info().best_block_hash != original_best {
+			self.prepare_sealing();
+		}
+
 		imported
 	}
 
@@ -403,8 +417,82 @@ impl Client {
 			BlockId::Latest => Some(self.chain.read().unwrap().best_block_number())
 		}
 	}
+
+	/// Get the author that we will seal blocks as.
+	pub fn author(&self) -> Address {
+		self.author.read().unwrap().clone()
+	}
+
+	/// Set the author that we will seal blocks as.
+	pub fn set_author(&self, author: Address) {
+		*self.author.write().unwrap() = author;
+	}
+
+	/// Get the extra_data that we will seal blocks wuth.
+	pub fn extra_data(&self) -> Bytes {
+		self.extra_data.read().unwrap().clone()
+	}
+
+	/// Set the extra_data that we will seal blocks with.
+	pub fn set_extra_data(&self, extra_data: Bytes) {
+		*self.extra_data.write().unwrap() = extra_data;
+	}
+
+	/// New chain head event. Restart mining operation.
+	pub fn prepare_sealing(&self) {
+		let h = self.chain.read().unwrap().best_block_hash();
+		let mut b = OpenBlock::new(
+			self.engine.deref().deref(),
+			self.state_db.lock().unwrap().clone(),
+			match self.chain.read().unwrap().block_header(&h) { Some(ref x) => x, None => {return;} },
+			self.build_last_hashes(h.clone()),
+			self.author(),
+			self.extra_data()
+		);
+
+		self.chain.read().unwrap().find_uncle_headers(&h).into_iter().foreach(|h| { b.push_uncle(h).unwrap(); });
+
+		// TODO: push transactions.
+
+		let b = b.close();
+		trace!("Sealing: number={}, hash={}, diff={}", b.hash(), b.block().header().difficulty(), b.block().header().number());
+		*self.sealing_block.lock().unwrap() = Some(b);
+	}
+
+	/// Grab the `ClosedBlock` that we want to be sealed. Comes as a mutex that you have to lock.
+	pub fn sealing_block(&self) -> &Mutex<Option<ClosedBlock>> {
+		if self.sealing_block.lock().unwrap().is_none() {
+			self.prepare_sealing();
+		}
+		&self.sealing_block
+	}
+
+	/// Submit `seal` as a valid solution for the header of `pow_hash`.
+	/// Will check the seal, but not actually insert the block into the chain.
+	pub fn submit_seal(&self, pow_hash: H256, seal: Vec<Bytes>) -> Result<(), Error> {
+		let mut maybe_b = self.sealing_block.lock().unwrap();
+		match *maybe_b {
+			Some(ref b) if b.hash() == pow_hash => {}
+			_ => { return Err(Error::PowHashInvalid); }
+		}
+
+		let b = maybe_b.take();
+		match b.unwrap().try_seal(self.engine.deref().deref(), seal) {
+			Err(old) => {
+				*maybe_b = Some(old);
+				Err(Error::PowInvalid)
+			}
+			Ok(sealed) => {
+				// TODO: commit DB from `sealed.drain` and make a VerifiedBlock to skip running the transactions twice.
+				try!(self.import_block(sealed.rlp_bytes()));
+				Ok(())
+			}
+		}
+	}
 }
 
+// TODO: need MinerService MinerIoHandler
+
 impl BlockChainClient for Client {
 	fn block_header(&self, id: BlockId) -> Option<Bytes> {
 		let chain = self.chain.read().unwrap();
@@ -477,12 +565,14 @@ impl BlockChainClient for Client {
 	}
 
 	fn import_block(&self, bytes: Bytes) -> ImportResult {
-		let header = BlockView::new(&bytes).header();
-		if self.chain.read().unwrap().is_known(&header.hash()) {
-			return Err(ImportError::AlreadyInChain);
-		}
-		if self.block_status(BlockId::Hash(header.parent_hash)) == BlockStatus::Unknown {
-			return Err(ImportError::UnknownParent);
+		{
+			let header = BlockView::new(&bytes).header_view();
+			if self.chain.read().unwrap().is_known(&header.sha3()) {
+				return Err(x!(ImportError::AlreadyInChain));
+			}
+			if self.block_status(BlockId::Hash(header.parent_hash())) == BlockStatus::Unknown {
+				return Err(x!(BlockError::UnknownParent(header.parent_hash())));
+			}
 		}
 		self.block_queue.write().unwrap().import_block(bytes)
 	}
diff --git a/ethcore/src/engine.rs b/ethcore/src/engine.rs
index f86c943ee..d607ce2e2 100644
--- a/ethcore/src/engine.rs
+++ b/ethcore/src/engine.rs
@@ -30,8 +30,6 @@ pub trait Engine : Sync + Send {
 
 	/// The number of additional header fields required for this engine.
 	fn seal_fields(&self) -> usize { 0 }
-	/// Default values of the additional fields RLP-encoded in a raw (non-list) harness.
-	fn seal_rlp(&self) -> Bytes { vec![] }
 
 	/// Additional engine-specific information for the user/developer concerning `header`.
 	fn extra_info(&self, _header: &Header) -> HashMap<String, String> { HashMap::new() }
@@ -76,9 +74,20 @@ pub trait Engine : Sync + Send {
 	/// Verify a particular transaction is valid.
 	fn verify_transaction(&self, _t: &SignedTransaction, _header: &Header) -> Result<(), Error> { Ok(()) }
 
-	/// Don't forget to call Super::populateFromParent when subclassing & overriding.
+	/// Verify the seal of a block. This is an auxilliary method that actually just calls other `verify_` methods
+	/// to get the job done. By default it must pass `verify_basic` and `verify_block_unordered`. If more or fewer
+	/// methods are needed for an Engine, this may be overridden.
+	fn verify_block_seal(&self, header: &Header) -> Result<(), Error> {
+		self.verify_block_basic(header, None).and_then(|_| self.verify_block_unordered(header, None))
+	}
+
+	/// Don't forget to call Super::populate_from_parent when subclassing & overriding.
 	// TODO: consider including State in the params.
-	fn populate_from_parent(&self, _header: &mut Header, _parent: &Header) {}
+	fn populate_from_parent(&self, header: &mut Header, parent: &Header) {
+		header.difficulty = parent.difficulty;
+		header.gas_limit = parent.gas_limit;
+		header.note_dirty();
+	}
 
 	// TODO: builtin contract routing - to do this properly, it will require removing the built-in configuration-reading logic
 	// from Spec into here and removing the Spec::builtins field.
diff --git a/ethcore/src/error.rs b/ethcore/src/error.rs
index f75f338bf..824d8da90 100644
--- a/ethcore/src/error.rs
+++ b/ethcore/src/error.rs
@@ -131,25 +131,14 @@ pub enum BlockError {
 #[derive(Debug)]
 /// Import to the block queue result
 pub enum ImportError {
-	/// Bad block detected
-	Bad(Option<Error>),
-	/// Already in the block chain
+	/// Already in the block chain.
 	AlreadyInChain,
-	/// Already in the block queue
+	/// Already in the block queue.
 	AlreadyQueued,
-	/// Unknown parent
-	UnknownParent,
+	/// Already marked as bad from a previous import (could mean parent is bad).
+	KnownBad,
 }
 
-impl From<Error> for ImportError {
-	fn from(err: Error) -> ImportError {
-		ImportError::Bad(Some(err))
-	}
-}
-
-/// Result of import block operation.
-pub type ImportResult = Result<H256, ImportError>;
-
 #[derive(Debug)]
 /// General error type which should be capable of representing all errors in ethcore.
 pub enum Error {
@@ -163,14 +152,29 @@ pub enum Error {
 	Execution(ExecutionError),
 	/// Error concerning transaction processing.
 	Transaction(TransactionError),
+	/// Error concerning block import.
+	Import(ImportError),
+	/// PoW hash is invalid or out of date.
+	PowHashInvalid,
+	/// The value of the nonce or mishash is invalid.
+	PowInvalid,
 }
 
+/// Result of import block operation.
+pub type ImportResult = Result<H256, Error>;
+
 impl From<TransactionError> for Error {
 	fn from(err: TransactionError) -> Error {
 		Error::Transaction(err)
 	}
 }
 
+impl From<ImportError> for Error {
+	fn from(err: ImportError) -> Error {
+		Error::Import(err)
+	}
+}
+
 impl From<BlockError> for Error {
 	fn from(err: BlockError) -> Error {
 		Error::Block(err)
diff --git a/ethcore/src/ethereum/ethash.rs b/ethcore/src/ethereum/ethash.rs
index 54f02524d..f9810b964 100644
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -74,8 +74,6 @@ impl Engine for Ethash {
 	fn version(&self) -> SemanticVersion { SemanticVersion::new(1, 0, 0) }
 	// Two fields - mix
 	fn seal_fields(&self) -> usize { 2 }
-	// Two empty data items in RLP.
-	fn seal_rlp(&self) -> Bytes { encode(&H64::new()).to_vec() }
 
 	/// Additional engine-specific information for the user/developer concerning `header`.
 	fn extra_info(&self, _header: &Header) -> HashMap<String, String> { HashMap::new() }
@@ -106,7 +104,7 @@ impl Engine for Ethash {
 				max(gas_floor_target, gas_limit - gas_limit / bound_divisor + x!(1) + (header.gas_used * x!(6) / x!(5)) / bound_divisor)
 			}
 		};
-
+		header.note_dirty();
 //		info!("ethash: populate_from_parent #{}: difficulty={} and gas_limit={}", header.number, header.difficulty, header.gas_limit);
 	}
 
@@ -144,9 +142,10 @@ impl Engine for Ethash {
 		}
 
 		let difficulty = Ethash::boundary_to_difficulty(&Ethash::from_ethash(quick_get_difficulty(
-				&Ethash::to_ethash(header.bare_hash()),
-				header.nonce().low_u64(),
-				&Ethash::to_ethash(header.mix_hash()))));
+			&Ethash::to_ethash(header.bare_hash()),
+			header.nonce().low_u64(),
+			&Ethash::to_ethash(header.mix_hash())
+		)));
 		if difficulty < header.difficulty {
 			return Err(From::from(BlockError::InvalidProofOfWork(OutOfBounds { min: Some(header.difficulty), max: None, found: difficulty })));
 		}
@@ -241,10 +240,21 @@ impl Ethash {
 		target
 	}
 
-	fn boundary_to_difficulty(boundary: &H256) -> U256 {
+	/// Convert an Ethash boundary to its original difficulty. Basically just `f(x) = 2^256 / x`.
+	pub fn boundary_to_difficulty(boundary: &H256) -> U256 {
 		U256::from((U512::one() << 256) / x!(U256::from(boundary.as_slice())))
 	}
 
+	/// Convert an Ethash difficulty to the target boundary. Basically just `f(x) = 2^256 / x`.
+	pub fn difficulty_to_boundary(difficulty: &U256) -> H256 {
+		x!(U256::from((U512::one() << 256) / x!(difficulty)))
+	}
+
+	/// Given the `block_number`, determine the seed hash for Ethash.
+	pub fn get_seedhash(number: BlockNumber) -> H256 {
+		Self::from_ethash(ethash::get_seedhash(number))
+	}
+
 	fn to_ethash(hash: H256) -> EH256 {
 		unsafe { mem::transmute(hash) }
 	}
@@ -255,12 +265,20 @@ impl Ethash {
 }
 
 impl Header {
-	fn nonce(&self) -> H64 {
+	/// Get the none field of the header.
+	pub fn nonce(&self) -> H64 {
 		decode(&self.seal()[1])
 	}
-	fn mix_hash(&self) -> H256 {
+
+	/// Get the mix hash field of the header.
+	pub fn mix_hash(&self) -> H256 {
 		decode(&self.seal()[0])
 	}
+
+	/// Set the nonce and mix hash fields of the header.
+	pub fn set_nonce_and_mix_hash(&mut self, nonce: &H64, mix_hash: &H256) {
+		self.seal = vec![encode(mix_hash).to_vec(), encode(nonce).to_vec()];
+	}
 }
 
 #[cfg(test)]
diff --git a/ethcore/src/header.rs b/ethcore/src/header.rs
index 6ee682544..cc02d84db 100644
--- a/ethcore/src/header.rs
+++ b/ethcore/src/header.rs
@@ -102,10 +102,12 @@ impl Header {
 		Self::default()
 	}
 
-	/// Get the number field of the header.
-	pub fn number(&self) -> BlockNumber { self.number }
+	/// Get the parent_hash field of the header.
+	pub fn parent_hash(&self) -> &H256 { &self.parent_hash }
 	/// Get the timestamp field of the header.
 	pub fn timestamp(&self) -> u64 { self.timestamp }
+	/// Get the number field of the header.
+	pub fn number(&self) -> BlockNumber { self.number }
 	/// Get the author field of the header.
 	pub fn author(&self) -> &Address { &self.author }
 
@@ -127,11 +129,13 @@ impl Header {
 	// TODO: seal_at, set_seal_at &c.
 
 	/// Set the number field of the header.
-	pub fn set_number(&mut self, a: BlockNumber) { self.number = a; self.note_dirty(); }
+	pub fn set_parent_hash(&mut self, a: H256) { self.parent_hash = a; self.note_dirty(); }
 	/// Set the timestamp field of the header.
 	pub fn set_timestamp(&mut self, a: u64) { self.timestamp = a; self.note_dirty(); }
 	/// Set the timestamp field of the header to the current time.
-	pub fn set_timestamp_now(&mut self) { self.timestamp = now_utc().to_timespec().sec as u64; self.note_dirty(); }
+	pub fn set_timestamp_now(&mut self, but_later_than: u64) { self.timestamp = max(now_utc().to_timespec().sec as u64, but_later_than + 1); self.note_dirty(); }
+	/// Set the number field of the header.
+	pub fn set_number(&mut self, a: BlockNumber) { self.number = a; self.note_dirty(); }
 	/// Set the author field of the header.
 	pub fn set_author(&mut self, a: Address) { if a != self.author { self.author = a; self.note_dirty(); } }
 
diff --git a/ethcore/src/json_tests/state.rs b/ethcore/src/json_tests/state.rs
index b5f28444a..f6b5751a7 100644
--- a/ethcore/src/json_tests/state.rs
+++ b/ethcore/src/json_tests/state.rs
@@ -115,7 +115,7 @@ declare_test!{StateTests_stSolidityTest, "StateTests/stSolidityTest"}
 declare_test!{StateTests_stSpecialTest, "StateTests/stSpecialTest"}
 declare_test!{StateTests_stSystemOperationsTest, "StateTests/stSystemOperationsTest"}
 declare_test!{StateTests_stTransactionTest, "StateTests/stTransactionTest"}
-//declare_test!{StateTests_stTransitionTest, "StateTests/stTransitionTest"}
+declare_test!{StateTests_stTransitionTest, "StateTests/stTransitionTest"}
 declare_test!{StateTests_stWalletTest, "StateTests/stWalletTest"}
 
 
diff --git a/ethcore/src/tests/client.rs b/ethcore/src/tests/client.rs
index e2671d63e..001d1729b 100644
--- a/ethcore/src/tests/client.rs
+++ b/ethcore/src/tests/client.rs
@@ -15,6 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use client::{BlockChainClient, Client, ClientConfig, BlockId};
+use block::IsBlock;
 use tests::helpers::*;
 use common::*;
 use devtools::*;
@@ -125,3 +126,22 @@ fn can_handle_long_fork() {
 	}
 	assert_eq!(2000, client.chain_info().best_block_number);
 }
+
+#[test]
+fn can_mine() {
+	let dummy_blocks = get_good_dummy_block_seq(2);
+	let client_result = get_test_client_with_blocks(vec![dummy_blocks[0].clone()]);
+	let client = client_result.reference();
+	let b = client.sealing_block();
+	let pow_hash = {
+		let u = b.lock().unwrap();
+		match *u {
+			Some(ref b) => {
+				assert_eq!(*b.block().header().parent_hash(), BlockView::new(&dummy_blocks[0]).header_view().sha3());
+				b.hash()
+			}
+			None => { panic!(); }
+		}
+	};
+	assert!(client.submit_seal(pow_hash, vec![]).is_ok());
+}
diff --git a/ethcore/src/verification.rs b/ethcore/src/verification.rs
index ad5efd24a..f52e2e1e4 100644
--- a/ethcore/src/verification.rs
+++ b/ethcore/src/verification.rs
@@ -26,7 +26,7 @@ use engine::Engine;
 use blockchain::*;
 
 /// Preprocessed block data gathered in `verify_block_unordered` call
-pub struct PreVerifiedBlock {
+pub struct PreverifiedBlock {
 	/// Populated block header
 	pub header: Header,
 	/// Populated block transactions
@@ -55,8 +55,8 @@ pub fn verify_block_basic(header: &Header, bytes: &[u8], engine: &Engine) -> Res
 
 /// Phase 2 verification. Perform costly checks such as transaction signatures and block nonce for ethash.
 /// Still operates on a individual block
-/// Returns a PreVerifiedBlock structure populated with transactions
-pub fn verify_block_unordered(header: Header, bytes: Bytes, engine: &Engine) -> Result<PreVerifiedBlock, Error> {
+/// Returns a PreverifiedBlock structure populated with transactions
+pub fn verify_block_unordered(header: Header, bytes: Bytes, engine: &Engine) -> Result<PreverifiedBlock, Error> {
 	try!(engine.verify_block_unordered(&header, Some(&bytes)));
 	for u in Rlp::new(&bytes).at(2).iter().map(|rlp| rlp.as_val::<Header>()) {
 		try!(engine.verify_block_unordered(&u, None));
@@ -70,7 +70,7 @@ pub fn verify_block_unordered(header: Header, bytes: Bytes, engine: &Engine) ->
 			transactions.push(t);
 		}
 	}
-	Ok(PreVerifiedBlock {
+	Ok(PreverifiedBlock {
 		header: header,
 		transactions: transactions,
 		bytes: bytes,
diff --git a/parity/main.rs b/parity/main.rs
index 3d0d183a3..b991f36cd 100644
--- a/parity/main.rs
+++ b/parity/main.rs
@@ -85,6 +85,10 @@ Options:
   --jsonrpc-url URL        Specify URL for JSON-RPC API server [default: 127.0.0.1:8545].
   --jsonrpc-cors URL       Specify CORS header for JSON-RPC API responses [default: null].
 
+  --author ADDRESS         Specify the block author (aka "coinbase") address for sending block rewards
+                           from sealed blocks [default: 0037a6b811ffeb6e072da21179d11b1406371c63].
+  --extra-data STRING      Specify a custom extra-data for authored blocks, no more than 32 characters.
+
   -l --logging LOGGING     Specify the logging level.
   -v --version             Show information about version.
   -h --help                Show this screen.
@@ -114,6 +118,8 @@ struct Args {
 	flag_jsonrpc_cors: String,
 	flag_logging: Option<String>,
 	flag_version: bool,
+	flag_author: String,
+	flag_extra_data: Option<String>,
 }
 
 fn setup_log(init: &Option<String>) {
@@ -196,6 +202,18 @@ impl Configuration {
 		self.args.flag_db_path.replace("$HOME", env::home_dir().unwrap().to_str().unwrap())
 	}
 
+	fn author(&self) -> Address {
+		Address::from_str(&self.args.flag_author).unwrap_or_else(|_| die!("{}: Invalid address for --author. Must be 40 hex characters, without the 0x at the beginning.", self.args.flag_author))
+	}
+
+	fn extra_data(&self) -> Bytes {
+		match self.args.flag_extra_data {
+			Some(ref x) if x.len() <= 32 => x.as_bytes().to_owned(),
+			None => version_data(),
+			Some(ref x) => { die!("{}: Extra data must be at most 32 characters.", x); }
+		}
+	}
+
 	fn _keys_path(&self) -> String {
 		self.args.flag_keys_path.replace("$HOME", env::home_dir().unwrap().to_str().unwrap())
 	}
@@ -296,6 +314,8 @@ impl Configuration {
 		client_config.queue.max_mem_use = self.args.flag_queue_max_size;
 		let mut service = ClientService::start(client_config, spec, net_settings, &Path::new(&self.path())).unwrap();
 		let client = service.client().clone();
+		client.set_author(self.author());
+		client.set_extra_data(self.extra_data());
 
 		// Sync
 		let sync = EthSync::register(service.network(), sync_config, client);
@@ -354,7 +374,6 @@ impl Default for Informant {
 }
 
 impl Informant {
-
 	fn format_bytes(b: usize) -> String {
 		match binary_prefix(b as f64) {
 			Standalone(bytes)   => format!("{} bytes", bytes),
diff --git a/rpc/Cargo.toml b/rpc/Cargo.toml
index b9ca9deac..086fb19c1 100644
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@@ -9,12 +9,14 @@ build = "build.rs"
 [lib]
 
 [dependencies]
+log = "0.3"
 serde = "0.7.0"
 serde_json = "0.7.0"
 jsonrpc-core = "1.2"
 jsonrpc-http-server = "2.1"
 ethcore-util = { path = "../util" }
 ethcore = { path = "../ethcore" }
+ethash = { path = "../ethash" }
 ethsync = { path = "../sync" }
 clippy = { version = "0.0.44", optional = true }
 rustc-serialize = "0.3"
diff --git a/rpc/src/v1/impls/eth.rs b/rpc/src/v1/impls/eth.rs
index 0dd5714d2..71d05053c 100644
--- a/rpc/src/v1/impls/eth.rs
+++ b/rpc/src/v1/impls/eth.rs
@@ -15,13 +15,17 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Eth rpc implementation.
-use std::sync::{Arc, Weak};
 use ethsync::{EthSync, SyncState};
 use jsonrpc_core::*;
 use util::numbers::*;
 use util::sha3::*;
+use util::standard::{RwLock, HashMap, Arc, Weak};
+use util::rlp::encode;
 use ethcore::client::*;
+use ethcore::block::{IsBlock};
 use ethcore::views::*;
+//#[macro_use] extern crate log;
+use ethcore::ethereum::Ethash;
 use ethcore::ethereum::denominations::shannon;
 use v1::traits::{Eth, EthFilter};
 use v1::types::{Block, BlockTransactions, BlockNumber, Bytes, SyncStatus, SyncInfo, Transaction, OptionalValue, Index, Filter, Log};
@@ -29,7 +33,8 @@ use v1::types::{Block, BlockTransactions, BlockNumber, Bytes, SyncStatus, SyncIn
 /// Eth rpc implementation.
 pub struct EthClient {
 	client: Weak<Client>,
-	sync: Weak<EthSync>
+	sync: Weak<EthSync>,
+	hashrates: RwLock<HashMap<H256, u64>>,
 }
 
 impl EthClient {
@@ -37,7 +42,8 @@ impl EthClient {
 	pub fn new(client: &Arc<Client>, sync: &Arc<EthSync>) -> Self {
 		EthClient {
 			client: Arc::downgrade(client),
-			sync: Arc::downgrade(sync)
+			sync: Arc::downgrade(sync),
+			hashrates: RwLock::new(HashMap::new()),
 		}
 	}
 
@@ -124,7 +130,7 @@ impl Eth for EthClient {
 	// TODO: return real value of mining once it's implemented.
 	fn is_mining(&self, params: Params) -> Result<Value, Error> {
 		match params {
-			Params::None => Ok(Value::Bool(false)),
+			Params::None => to_value(&!self.hashrates.read().unwrap().is_empty()),
 			_ => Err(Error::invalid_params())
 		}
 	}
@@ -132,7 +138,7 @@ impl Eth for EthClient {
 	// TODO: return real hashrate once we have mining
 	fn hashrate(&self, params: Params) -> Result<Value, Error> {
 		match params {
-			Params::None => to_value(&U256::zero()),
+			Params::None => to_value(&self.hashrates.read().unwrap().iter().fold(0u64, |sum, (_, v)| sum + v)),
 			_ => Err(Error::invalid_params())
 		}
 	}
@@ -208,6 +214,43 @@ impl Eth for EthClient {
 				to_value(&logs)
 			})
 	}
+
+	fn work(&self, params: Params) -> Result<Value, Error> {
+		match params {
+			Params::None => {
+				let c = take_weak!(self.client);
+				let u = c.sealing_block().lock().unwrap();
+				match *u {
+					Some(ref b) => {
+						let pow_hash = b.hash();
+						let target = Ethash::difficulty_to_boundary(b.block().header().difficulty());
+						let seed_hash = Ethash::get_seedhash(b.block().header().number());
+						to_value(&(pow_hash, seed_hash, target))
+					}
+					_ => Err(Error::invalid_params())
+				}
+			},
+			_ => Err(Error::invalid_params())
+		}
+	}
+
+	fn submit_work(&self, params: Params) -> Result<Value, Error> {
+		from_params::<(H64, H256, H256)>(params).and_then(|(nonce, pow_hash, mix_hash)| {
+//			trace!("Decoded: nonce={}, pow_hash={}, mix_hash={}", nonce, pow_hash, mix_hash);
+			let c = take_weak!(self.client);
+			let seal = vec![encode(&mix_hash).to_vec(), encode(&nonce).to_vec()];
+			let r = c.submit_seal(pow_hash, seal);
+			to_value(&r.is_ok())
+		})
+	}
+
+	fn submit_hashrate(&self, params: Params) -> Result<Value, Error> {
+		// TODO: Index should be U256.
+		from_params::<(Index, H256)>(params).and_then(|(rate, id)| {
+			self.hashrates.write().unwrap().insert(id, rate.value() as u64);
+			to_value(&true)
+		})
+	}
 }
 
 /// Eth filter rpc implementation.
diff --git a/rpc/src/v1/impls/web3.rs b/rpc/src/v1/impls/web3.rs
index 0a237d56b..4d31f73ae 100644
--- a/rpc/src/v1/impls/web3.rs
+++ b/rpc/src/v1/impls/web3.rs
@@ -31,7 +31,7 @@ impl Web3 for Web3Client {
 	fn client_version(&self, params: Params) -> Result<Value, Error> {
 		match params {
 			Params::None => {
-				Ok(Value::String(version())),
+				Ok(Value::String(version().to_owned().replace("Parity/", "Parity//"))),
 			}
 			_ => Err(Error::invalid_params())
 		}
diff --git a/sync/src/chain.rs b/sync/src/chain.rs
index 85380f3cd..601ca3869 100644
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@@ -477,19 +477,19 @@ impl ChainSync {
 		// TODO: Decompose block and add to self.headers and self.bodies instead
 		if header.number == From::from(self.current_base_block() + 1) {
 			match io.chain().import_block(block_rlp.as_raw().to_vec()) {
-				Err(ImportError::AlreadyInChain) => {
+				Err(Error::Import(ImportError::AlreadyInChain)) => {
 					trace!(target: "sync", "New block already in chain {:?}", h);
 				},
-				Err(ImportError::AlreadyQueued) => {
+				Err(Error::Import(ImportError::AlreadyQueued)) => {
 					trace!(target: "sync", "New block already queued {:?}", h);
 				},
 				Ok(_) => {
 					self.last_imported_block = Some(header.number);
 					trace!(target: "sync", "New block queued {:?}", h);
 				},
-				Err(ImportError::UnknownParent) => {
+				Err(Error::Block(BlockError::UnknownParent(p))) => {
 					unknown = true;
-					trace!(target: "sync", "New block with unknown parent {:?}", h);
+					trace!(target: "sync", "New block with unknown parent ({:?}) {:?}", p, h);
 				},
 				Err(e) => {
 					debug!(target: "sync", "Bad new block {:?} : {:?}", h, e);
@@ -781,12 +781,12 @@ impl ChainSync {
 				}
 
 				match io.chain().import_block(block_rlp.out()) {
-					Err(ImportError::AlreadyInChain) => {
+					Err(Error::Import(ImportError::AlreadyInChain)) => {
 						trace!(target: "sync", "Block already in chain {:?}", h);
 						self.last_imported_block = Some(headers.0 + i as BlockNumber);
 						self.last_imported_hash = Some(h.clone());
 					},
-					Err(ImportError::AlreadyQueued) => {
+					Err(Error::Import(ImportError::AlreadyQueued)) => {
 						trace!(target: "sync", "Block already queued {:?}", h);
 						self.last_imported_block = Some(headers.0 + i as BlockNumber);
 						self.last_imported_hash = Some(h.clone());
diff --git a/util/bigint/src/uint.rs b/util/bigint/src/uint.rs
index 5b67ba41d..0691ec09b 100644
--- a/util/bigint/src/uint.rs
+++ b/util/bigint/src/uint.rs
@@ -1266,6 +1266,33 @@ impl From<U512> for U256 {
 	}
 }
 
+impl<'a> From<&'a U256> for U512 {
+	fn from(value: &'a U256) -> U512 {
+		let U256(ref arr) = *value;
+		let mut ret = [0; 8];
+		ret[0] = arr[0];
+		ret[1] = arr[1];
+		ret[2] = arr[2];
+		ret[3] = arr[3];
+		U512(ret)
+	}
+}
+
+impl<'a> From<&'a U512> for U256 {
+	fn from(value: &'a U512) -> U256 {
+		let U512(ref arr) = *value;
+		if arr[4] | arr[5] | arr[6] | arr[7] != 0 {
+			panic!("Overflow");
+		}
+		let mut ret = [0; 4];
+		ret[0] = arr[0];
+		ret[1] = arr[1];
+		ret[2] = arr[2];
+		ret[3] = arr[3];
+		U256(ret)
+	}
+}
+
 impl From<U256> for U128 {
 	fn from(value: U256) -> U128 {
 		let U256(ref arr) = value;
diff --git a/util/src/keys/geth_import.rs b/util/src/keys/geth_import.rs
index cdbd9b213..dbd9f0fe0 100644
--- a/util/src/keys/geth_import.rs
+++ b/util/src/keys/geth_import.rs
@@ -99,10 +99,20 @@ mod tests {
 	use common::*;
 	use keys::store::SecretStore;
 
+	fn test_path() -> &'static str {
+		match ::std::fs::metadata("res") {
+			Ok(_) => "res/geth_keystore",
+			Err(_) => "util/res/geth_keystore"
+		}
+	}
+
+	fn test_path_param(param_val: &'static str) -> String {
+		test_path().to_owned() + param_val
+	}
 
 	#[test]
 	fn can_enumerate() {
-		let keys = enumerate_geth_keys(Path::new("res/geth_keystore")).unwrap();
+		let keys = enumerate_geth_keys(Path::new(test_path())).unwrap();
 		assert_eq!(2, keys.len());
 	}
 
@@ -110,7 +120,7 @@ mod tests {
 	fn can_import() {
 		let temp = ::devtools::RandomTempPath::create_dir();
 		let mut secret_store = SecretStore::new_in(temp.as_path());
-		import_geth_key(&mut secret_store, Path::new("res/geth_keystore/UTC--2016-02-17T09-20-45.721400158Z--3f49624084b67849c7b4e805c5988c21a430f9d9")).unwrap();
+		import_geth_key(&mut secret_store, Path::new(&test_path_param("/UTC--2016-02-17T09-20-45.721400158Z--3f49624084b67849c7b4e805c5988c21a430f9d9"))).unwrap();
 		let key = secret_store.account(&Address::from_str("3f49624084b67849c7b4e805c5988c21a430f9d9").unwrap());
 		assert!(key.is_some());
 	}
@@ -119,7 +129,7 @@ mod tests {
 	fn can_import_directory() {
 		let temp = ::devtools::RandomTempPath::create_dir();
 		let mut secret_store = SecretStore::new_in(temp.as_path());
-		import_geth_keys(&mut secret_store, Path::new("res/geth_keystore")).unwrap();
+		import_geth_keys(&mut secret_store, Path::new(test_path())).unwrap();
 
 		let key = secret_store.account(&Address::from_str("3f49624084b67849c7b4e805c5988c21a430f9d9").unwrap());
 		assert!(key.is_some());
@@ -134,7 +144,7 @@ mod tests {
 		let temp = ::devtools::RandomTempPath::create_dir();
 		{
 			let mut secret_store = SecretStore::new_in(temp.as_path());
-			import_geth_keys(&mut secret_store, Path::new("res/geth_keystore")).unwrap();
+			import_geth_keys(&mut secret_store, Path::new(test_path())).unwrap();
 		}
 
 		let key_directory = KeyDirectory::new(&temp.as_path());
@@ -156,7 +166,7 @@ mod tests {
 
 		let temp = ::devtools::RandomTempPath::create_dir();
 		let mut secret_store = SecretStore::new_in(temp.as_path());
-		import_geth_keys(&mut secret_store, Path::new("res/geth_keystore")).unwrap();
+		import_geth_keys(&mut secret_store, Path::new(test_path())).unwrap();
 
 		let val = secret_store.get::<Bytes>(&H128::from_str("62a0ad73556d496a8e1c0783d30d3ace").unwrap(), "123");
 		assert!(val.is_ok());
diff --git a/util/src/misc.rs b/util/src/misc.rs
index 289f1c50c..39ccbf2da 100644
--- a/util/src/misc.rs
+++ b/util/src/misc.rs
@@ -18,6 +18,7 @@
 
 use std::fs::File;
 use common::*;
+use rlp::{Stream, RlpStream};
 use target_info::Target;
 use rustc_version;
 
@@ -69,5 +70,19 @@ pub fn contents(name: &str) -> Result<Bytes, UtilError> {
 
 /// Get the standard version string for this software.
 pub fn version() -> String {
-	format!("Parity//{}-{}-{}/{}-{}-{}/rustc{}", env!("CARGO_PKG_VERSION"), short_sha(), commit_date().replace("-", ""), Target::arch(), Target::os(), Target::env(), rustc_version::version())
+	format!("Parity/v{}-{}-{}/{}-{}-{}/rustc{}", env!("CARGO_PKG_VERSION"), short_sha(), commit_date().replace("-", ""), Target::arch(), Target::os(), Target::env(), rustc_version::version())
+}
+
+/// Get the standard version data for this software.
+pub fn version_data() -> Bytes {
+	let mut s = RlpStream::new_list(4);
+	let v =
+		(u32::from_str(env!("CARGO_PKG_VERSION_MAJOR")).unwrap() << 16) +
+		(u32::from_str(env!("CARGO_PKG_VERSION_MINOR")).unwrap() << 8) +
+		u32::from_str(env!("CARGO_PKG_VERSION_PATCH")).unwrap();
+	s.append(&v);
+	s.append(&"Parity");
+	s.append(&format!("{}", rustc_version::version()));
+	s.append(&&Target::os()[0..2]);
+	s.out()
 }
\ No newline at end of file