diff --git a/chain/src/constants.rs b/chain/src/constants.rs
new file mode 100644
index 00000000..72ecc5f5
--- /dev/null
+++ b/chain/src/constants.rs
@@ -0,0 +1,22 @@
+
+// Below flags apply in the context of BIP 68
+// If this flag set, CTxIn::nSequence is NOT interpreted as a
+// relative lock-time.
+pub const SEQUENCE_LOCKTIME_DISABLE_FLAG: u32 = 1u32 << 31;
+
+// Setting nSequence to this value for every input in a transaction
+// disables nLockTime.
+pub const SEQUENCE_FINAL: u32 = 0xffffffff;
+
+// If CTxIn::nSequence encodes a relative lock-time and this flag
+// is set, the relative lock-time has units of 512 seconds,
+// otherwise it specifies blocks with a granularity of 1.
+pub const SEQUENCE_LOCKTIME_TYPE_FLAG: u32 = (1 << 22);
+
+// If CTxIn::nSequence encodes a relative lock-time, this mask is
+// applied to extract that lock-time from the sequence field.
+pub const SEQUENCE_LOCKTIME_MASK: u32 = 0x0000ffff;
+
+/// Threshold for `nLockTime`: below this value it is interpreted as block number,
+/// otherwise as UNIX timestamp.
+pub const LOCKTIME_THRESHOLD: u32 = 500000000; // Tue Nov  5 00:53:20 1985 UTC
diff --git a/db/src/indexed_block.rs b/chain/src/indexed_block.rs
similarity index 52%
rename from db/src/indexed_block.rs
rename to chain/src/indexed_block.rs
index e788a580..9e02979f 100644
--- a/db/src/indexed_block.rs
+++ b/chain/src/indexed_block.rs
@@ -1,9 +1,14 @@
-use primitives::hash::H256;
-use chain::{Block, OutPoint, TransactionOutput, merkle_root, Transaction};
-use serialization::{Serializable, serialized_list_size};
+use std::{io, cmp};
+use hash::H256;
+use ser::{
+	Serializable, serialized_list_size,
+	Deserializable, Reader, Error as ReaderError
+};
+use block::Block;
+use transaction::Transaction;
+use merkle_root::merkle_root;
 use indexed_header::IndexedBlockHeader;
 use indexed_transaction::IndexedTransaction;
-use {TransactionOutputObserver, PreviousTransactionOutputProvider};
 
 #[derive(Debug, Clone)]
 pub struct IndexedBlock {
@@ -11,40 +16,6 @@ pub struct IndexedBlock {
 	pub transactions: Vec<IndexedTransaction>,
 }
 
-impl PreviousTransactionOutputProvider for IndexedBlock {
-	fn previous_transaction_output(&self, prevout: &OutPoint) -> Option<TransactionOutput> {
-		let txs: &[_] = &self.transactions;
-		txs.previous_transaction_output(prevout)
-	}
-}
-
-impl TransactionOutputObserver for IndexedBlock {
-	fn is_spent(&self, _prevout: &OutPoint) -> Option<bool> {
-		// the code below is valid, but commented out due it's poor performance
-		// we could optimize it by indexing all outputs once
-		// let tx: IndexedTransaction = { .. }
-		// let indexed_outputs: IndexedOutputs = tx.indexed_outputs();
-		// indexed_outputs.is_spent()
-		None
-
-		// if previous transaction output appears more than once than we can safely
-		// tell that it's spent (double spent)
-
-		//let spends = self.transactions.iter()
-			//.flat_map(|tx| &tx.raw.inputs)
-			//.filter(|input| &input.previous_output == prevout)
-			//.take(2)
-			//.count();
-
-		//match spends {
-			//0 => None,
-			//1 => Some(false),
-			//2 => Some(true),
-			//_ => unreachable!("spends <= 2; self.take(2); qed"),
-		//}
-	}
-}
-
 impl From<Block> for IndexedBlock {
 	fn from(block: Block) -> Self {
 		let Block { block_header, transactions } = block;
@@ -56,6 +27,12 @@ impl From<Block> for IndexedBlock {
 	}
 }
 
+impl cmp::PartialEq for IndexedBlock {
+	fn eq(&self, other: &Self) -> bool {
+		self.header.hash == other.header.hash
+	}
+}
+
 impl IndexedBlock {
 	pub fn new(header: IndexedBlockHeader, transactions: Vec<IndexedTransaction>) -> Self {
 		IndexedBlock {
@@ -87,3 +64,14 @@ impl IndexedBlock {
 		self.transactions.iter().all(|tx| tx.raw.is_final_in_block(height, self.header.raw.time))
 	}
 }
+
+impl Deserializable for IndexedBlock {
+	fn deserialize<T>(reader: &mut Reader<T>) -> Result<Self, ReaderError> where T: io::Read {
+		let block = IndexedBlock {
+			header: try!(reader.read()),
+			transactions: try!(reader.read_list()),
+		};
+
+		Ok(block)
+	}
+}
diff --git a/chain/src/indexed_header.rs b/chain/src/indexed_header.rs
new file mode 100644
index 00000000..6e2142e9
--- /dev/null
+++ b/chain/src/indexed_header.rs
@@ -0,0 +1,48 @@
+use std::{io, cmp};
+use hash::H256;
+use ser::{Deserializable, Reader, Error as ReaderError};
+use block_header::BlockHeader;
+use read_and_hash::ReadAndHash;
+
+#[derive(Debug, Clone)]
+pub struct IndexedBlockHeader {
+	pub hash: H256,
+	pub raw: BlockHeader,
+}
+
+impl From<BlockHeader> for IndexedBlockHeader {
+	fn from(header: BlockHeader) -> Self {
+		IndexedBlockHeader {
+			hash: header.hash(),
+			raw: header,
+		}
+	}
+}
+
+impl IndexedBlockHeader {
+	pub fn new(hash: H256, header: BlockHeader) -> Self {
+		IndexedBlockHeader {
+			hash: hash,
+			raw: header,
+		}
+	}
+}
+
+impl cmp::PartialEq for IndexedBlockHeader {
+	fn eq(&self, other: &Self) -> bool {
+		self.hash == other.hash
+	}
+}
+
+impl Deserializable for IndexedBlockHeader {
+	fn deserialize<T>(reader: &mut Reader<T>) -> Result<Self, ReaderError> where T: io::Read {
+		let data = try!(reader.read_and_hash::<BlockHeader>());
+		// TODO: use len
+		let header = IndexedBlockHeader {
+			raw: data.data,
+			hash: data.hash,
+		};
+
+		Ok(header)
+	}
+}
diff --git a/chain/src/indexed_transaction.rs b/chain/src/indexed_transaction.rs
new file mode 100644
index 00000000..d15fd813
--- /dev/null
+++ b/chain/src/indexed_transaction.rs
@@ -0,0 +1,60 @@
+use std::{cmp, io, borrow};
+use hash::H256;
+use ser::{Deserializable, Reader, Error as ReaderError};
+use transaction::Transaction;
+use read_and_hash::ReadAndHash;
+
+#[derive(Debug, Clone)]
+pub struct IndexedTransaction {
+	pub hash: H256,
+	pub raw: Transaction,
+}
+
+impl From<Transaction> for IndexedTransaction {
+	fn from(tx: Transaction) -> Self {
+		IndexedTransaction {
+			hash: tx.hash(),
+			raw: tx,
+		}
+	}
+}
+
+impl IndexedTransaction {
+	pub fn new(hash: H256, transaction: Transaction) -> Self {
+		IndexedTransaction {
+			hash: hash,
+			raw: transaction,
+		}
+	}
+}
+
+impl cmp::PartialEq for IndexedTransaction {
+	fn eq(&self, other: &Self) -> bool {
+		self.hash == other.hash
+	}
+}
+
+impl Deserializable for IndexedTransaction {
+	fn deserialize<T>(reader: &mut Reader<T>) -> Result<Self, ReaderError> where T: io::Read {
+		let data = try!(reader.read_and_hash::<Transaction>());
+		// TODO: use len
+		let tx = IndexedTransaction {
+			raw: data.data,
+			hash: data.hash,
+		};
+
+		Ok(tx)
+	}
+}
+
+pub struct IndexedTransactionsRef<'a, T> where T: 'a {
+	pub transactions: &'a [T],
+}
+
+impl<'a, T> IndexedTransactionsRef<'a, T> where T: borrow::Borrow<IndexedTransaction> {
+	pub fn new(transactions: &'a [T]) -> Self {
+		IndexedTransactionsRef {
+			transactions: transactions,
+		}
+	}
+}
diff --git a/chain/src/lib.rs b/chain/src/lib.rs
index 08d8c4ee..7d0a59b7 100644
--- a/chain/src/lib.rs
+++ b/chain/src/lib.rs
@@ -4,27 +4,34 @@ extern crate primitives;
 extern crate bitcrypto as crypto;
 extern crate serialization as ser;
 
+pub mod constants;
+
 mod block;
 mod block_header;
 mod merkle_root;
 mod transaction;
 
+/// `IndexedBlock` extension
+mod read_and_hash;
+mod indexed_block;
+mod indexed_header;
+mod indexed_transaction;
+
 pub trait RepresentH256 {
-	fn h256(&self) -> primitives::hash::H256;
+	fn h256(&self) -> hash::H256;
 }
 
 pub use rustc_serialize::hex;
 pub use primitives::{hash, bytes, uint, compact};
 
-pub use self::block::Block;
-pub use self::block_header::BlockHeader;
-pub use self::merkle_root::merkle_root;
-pub use self::merkle_root::merkle_node_hash;
-pub use self::transaction::{
-	Transaction, TransactionInput, TransactionOutput, OutPoint,
-	SEQUENCE_LOCKTIME_DISABLE_FLAG, SEQUENCE_FINAL,
-	SEQUENCE_LOCKTIME_TYPE_FLAG, SEQUENCE_LOCKTIME_MASK,
-	LOCKTIME_THRESHOLD
-};
+pub use block::Block;
+pub use block_header::BlockHeader;
+pub use merkle_root::{merkle_root, merkle_node_hash};
+pub use transaction::{Transaction, TransactionInput, TransactionOutput, OutPoint};
+
+pub use read_and_hash::{ReadAndHash, HashedData};
+pub use indexed_block::IndexedBlock;
+pub use indexed_header::IndexedBlockHeader;
+pub use indexed_transaction::{IndexedTransaction, IndexedTransactionsRef};
 
 pub type ShortTransactionID = hash::H48;
diff --git a/chain/src/read_and_hash.rs b/chain/src/read_and_hash.rs
new file mode 100644
index 00000000..5c294dcf
--- /dev/null
+++ b/chain/src/read_and_hash.rs
@@ -0,0 +1,33 @@
+use std::io;
+use hash::H256;
+use crypto::{DHash256, Digest};
+use ser::{Reader, Error as ReaderError, Deserializable};
+
+pub struct HashedData<T> {
+	pub size: usize,
+	pub hash: H256,
+	pub data: T,
+}
+
+pub trait ReadAndHash {
+	fn read_and_hash<T>(&mut self) -> Result<HashedData<T>, ReaderError> where T: Deserializable;
+}
+
+impl<R> ReadAndHash for Reader<R> where R: io::Read {
+	fn read_and_hash<T>(&mut self) -> Result<HashedData<T>, ReaderError> where T: Deserializable {
+		let mut size = 0usize;
+		let mut hasher = DHash256::new();
+		let data = self.read_with_proxy(|bytes| {
+			size += bytes.len();
+			hasher.input(bytes);
+		})?;
+
+		let result = HashedData {
+			hash: hasher.finish(),
+			data: data,
+			size: size,
+		};
+
+		Ok(result)
+	}
+}
diff --git a/chain/src/transaction.rs b/chain/src/transaction.rs
index 8e6c984f..1f28a05c 100644
--- a/chain/src/transaction.rs
+++ b/chain/src/transaction.rs
@@ -11,28 +11,7 @@ use ser::{
 };
 use crypto::dhash256;
 use hash::H256;
-
-// Below flags apply in the context of BIP 68
-// If this flag set, CTxIn::nSequence is NOT interpreted as a
-// relative lock-time.
-pub const SEQUENCE_LOCKTIME_DISABLE_FLAG: u32 = 1u32 << 31;
-
-// Setting nSequence to this value for every input in a transaction
-// disables nLockTime.
-pub const SEQUENCE_FINAL: u32 = 0xffffffff;
-
-// If CTxIn::nSequence encodes a relative lock-time and this flag
-// is set, the relative lock-time has units of 512 seconds,
-// otherwise it specifies blocks with a granularity of 1.
-pub const SEQUENCE_LOCKTIME_TYPE_FLAG: u32 = (1 << 22);
-
-// If CTxIn::nSequence encodes a relative lock-time, this mask is
-// applied to extract that lock-time from the sequence field.
-pub const SEQUENCE_LOCKTIME_MASK: u32 = 0x0000ffff;
-
-/// Threshold for `nLockTime`: below this value it is interpreted as block number,
-/// otherwise as UNIX timestamp.
-pub const LOCKTIME_THRESHOLD: u32 = 500000000; // Tue Nov  5 00:53:20 1985 UTC
+use constants::{SEQUENCE_FINAL, LOCKTIME_THRESHOLD};
 
 #[derive(Debug, PartialEq, Eq, Clone, Default)]
 pub struct OutPoint {
diff --git a/crypto/src/lib.rs b/crypto/src/lib.rs
index 5fed6d43..02a11c3f 100644
--- a/crypto/src/lib.rs
+++ b/crypto/src/lib.rs
@@ -2,11 +2,11 @@ extern crate crypto as rcrypto;
 extern crate primitives;
 extern crate siphasher;
 
+pub use rcrypto::digest::Digest;
 use std::hash::Hasher;
 use rcrypto::sha1::Sha1;
 use rcrypto::sha2::Sha256;
 use rcrypto::ripemd160::Ripemd160;
-use rcrypto::digest::Digest;
 use siphasher::sip::SipHasher24;
 use primitives::hash::{H32, H160, H256};
 
@@ -72,6 +72,12 @@ impl DHash256 {
 	pub fn new() -> Self {
 		DHash256::default()
 	}
+
+	pub fn finish(mut self) -> H256 {
+		let mut result = H256::default();
+		self.result(&mut *result);
+		result
+	}
 }
 
 impl Digest for DHash256 {
diff --git a/db/src/block_stapler.rs b/db/src/block_stapler.rs
index 20d2cf45..af361db4 100644
--- a/db/src/block_stapler.rs
+++ b/db/src/block_stapler.rs
@@ -1,7 +1,7 @@
 use primitives::hash::H256;
-use super::{BlockLocation, IndexedBlock};
-use chain;
+use chain::{self, IndexedBlock};
 use error::Error;
+use super::BlockLocation;
 
 #[derive(Debug, PartialEq)]
 pub struct Reorganization {
diff --git a/db/src/impls.rs b/db/src/impls.rs
new file mode 100644
index 00000000..ceed0c60
--- /dev/null
+++ b/db/src/impls.rs
@@ -0,0 +1,49 @@
+use std::borrow::Borrow;
+use chain::{OutPoint, TransactionOutput, IndexedTransactionsRef, IndexedTransaction, IndexedBlock};
+use transaction_provider::PreviousTransactionOutputProvider;
+use transaction_meta_provider::TransactionOutputObserver;
+
+impl<'a, T> PreviousTransactionOutputProvider for IndexedTransactionsRef<'a, T>
+	where T: Borrow<IndexedTransaction> + Send + Sync {
+	fn previous_transaction_output(&self, prevout: &OutPoint) -> Option<TransactionOutput> {
+		self.transactions.iter()
+			.map(Borrow::borrow)
+			.find(|tx| tx.hash == prevout.hash)
+			.and_then(|tx| tx.raw.outputs.get(prevout.index as usize))
+			.cloned()
+	}
+}
+
+impl PreviousTransactionOutputProvider for IndexedBlock {
+	fn previous_transaction_output(&self, prevout: &OutPoint) -> Option<TransactionOutput> {
+		let txs = IndexedTransactionsRef::new(&self.transactions);
+		txs.previous_transaction_output(prevout)
+	}
+}
+
+impl TransactionOutputObserver for IndexedBlock {
+	fn is_spent(&self, _prevout: &OutPoint) -> Option<bool> {
+		// the code below is valid, but commented out due it's poor performance
+		// we could optimize it by indexing all outputs once
+		// let tx: IndexedTransaction = { .. }
+		// let indexed_outputs: IndexedOutputs = tx.indexed_outputs();
+		// indexed_outputs.is_spent()
+		None
+
+		// if previous transaction output appears more than once than we can safely
+		// tell that it's spent (double spent)
+
+		//let spends = self.transactions.iter()
+			//.flat_map(|tx| &tx.raw.inputs)
+			//.filter(|input| &input.previous_output == prevout)
+			//.take(2)
+			//.count();
+
+		//match spends {
+			//0 => None,
+			//1 => Some(false),
+			//2 => Some(true),
+			//_ => unreachable!("spends <= 2; self.take(2); qed"),
+		//}
+	}
+}
diff --git a/db/src/indexed_header.rs b/db/src/indexed_header.rs
deleted file mode 100644
index df117833..00000000
--- a/db/src/indexed_header.rs
+++ /dev/null
@@ -1,26 +0,0 @@
-use primitives::hash::H256;
-use chain::BlockHeader;
-
-#[derive(Debug, Clone)]
-pub struct IndexedBlockHeader {
-	pub hash: H256,
-	pub raw: BlockHeader,
-}
-
-impl From<BlockHeader> for IndexedBlockHeader {
-	fn from(header: BlockHeader) -> Self {
-		IndexedBlockHeader {
-			hash: header.hash(),
-			raw: header,
-		}
-	}
-}
-
-impl IndexedBlockHeader {
-	pub fn new(hash: H256, header: BlockHeader) -> Self {
-		IndexedBlockHeader {
-			hash: hash,
-			raw: header,
-		}
-	}
-}
diff --git a/db/src/indexed_transaction.rs b/db/src/indexed_transaction.rs
deleted file mode 100644
index bcfec139..00000000
--- a/db/src/indexed_transaction.rs
+++ /dev/null
@@ -1,43 +0,0 @@
-use std::cmp;
-use primitives::hash::H256;
-use chain::{Transaction, OutPoint, TransactionOutput};
-use PreviousTransactionOutputProvider;
-
-#[derive(Debug, Clone)]
-pub struct IndexedTransaction {
-	pub hash: H256,
-	pub raw: Transaction,
-}
-
-impl From<Transaction> for IndexedTransaction {
-	fn from(tx: Transaction) -> Self {
-		IndexedTransaction {
-			hash: tx.hash(),
-			raw: tx,
-		}
-	}
-}
-
-impl IndexedTransaction {
-	pub fn new(hash: H256, transaction: Transaction) -> Self {
-		IndexedTransaction {
-			hash: hash,
-			raw: transaction,
-		}
-	}
-}
-
-impl cmp::PartialEq for IndexedTransaction {
-	fn eq(&self, other: &Self) -> bool {
-		self.hash == other.hash
-	}
-}
-
-impl<'a> PreviousTransactionOutputProvider for &'a [IndexedTransaction] {
-	fn previous_transaction_output(&self, prevout: &OutPoint) -> Option<TransactionOutput> {
-		self.iter()
-			.find(|tx| tx.hash == prevout.hash)
-			.and_then(|tx| tx.raw.outputs.get(prevout.index as usize))
-			.cloned()
-	}
-}
diff --git a/db/src/lib.rs b/db/src/lib.rs
index 10a05309..1262e4f7 100644
--- a/db/src/lib.rs
+++ b/db/src/lib.rs
@@ -28,9 +28,7 @@ mod transaction_provider;
 mod transaction_meta_provider;
 mod error;
 mod update_context;
-mod indexed_block;
-mod indexed_header;
-mod indexed_transaction;
+mod impls;
 
 #[derive(Debug, Clone)]
 pub enum BlockRef {
@@ -75,9 +73,6 @@ pub use transaction_meta_provider::{TransactionMetaProvider, TransactionOutputOb
 pub use transaction_meta::TransactionMeta;
 pub use block_stapler::{BlockStapler, BlockInsertedChain};
 pub use block_provider::{BlockProvider, BlockHeaderProvider};
-pub use indexed_block::IndexedBlock;
-pub use indexed_header::IndexedBlockHeader;
-pub use indexed_transaction::IndexedTransaction;
 
 #[cfg(feature="dev")]
 pub use test_storage::TestStorage;
diff --git a/db/src/storage.rs b/db/src/storage.rs
index a7c5d6d5..72eacab6 100644
--- a/db/src/storage.rs
+++ b/db/src/storage.rs
@@ -4,14 +4,13 @@ use std::fs;
 use std::path::Path;
 use kvdb::{Database, DatabaseConfig};
 use byteorder::{LittleEndian, ByteOrder};
-use primitives::hash::H256;
-use primitives::bytes::Bytes;
-use super::{BlockRef, BestBlock, BlockLocation, IndexedBlock};
-use serialization::{serialize, deserialize};
-use chain;
 use parking_lot::RwLock;
 use lru_cache::LruCache;
 
+use primitives::hash::H256;
+use primitives::bytes::Bytes;
+use chain::{self, IndexedBlock, IndexedBlockHeader, IndexedTransaction};
+use serialization::{serialize, deserialize};
 use transaction_meta::TransactionMeta;
 use error::{Error, ConsistencyError, MetaError};
 use update_context::UpdateContext;
@@ -19,9 +18,7 @@ use block_provider::{BlockProvider, BlockHeaderProvider};
 use transaction_provider::{TransactionProvider, PreviousTransactionOutputProvider};
 use transaction_meta_provider::TransactionMetaProvider;
 use block_stapler::{BlockStapler, BlockInsertedChain, Reorganization};
-
-use indexed_header::IndexedBlockHeader;
-use indexed_transaction::IndexedTransaction;
+use super::{BlockRef, BestBlock, BlockLocation};
 
 pub const COL_COUNT: u32 = 10;
 pub const COL_META: u32 = 0;
diff --git a/db/src/test_storage.rs b/db/src/test_storage.rs
index c5b3928f..2ea1ce18 100644
--- a/db/src/test_storage.rs
+++ b/db/src/test_storage.rs
@@ -3,9 +3,9 @@
 use super::{
 	BlockRef, Store, Error, BestBlock, BlockLocation, BlockInsertedChain, BlockProvider,
 	BlockStapler, TransactionMetaProvider, TransactionProvider, PreviousTransactionOutputProvider,
-	IndexedBlock, BlockHeaderProvider,
+	BlockHeaderProvider,
 };
-use chain::{self, Block};
+use chain::{self, Block, IndexedBlock};
 use primitives::hash::H256;
 use serialization;
 use chain::bytes::Bytes;
diff --git a/import/src/block.rs b/import/src/block.rs
index 0cadd73f..fb893881 100644
--- a/import/src/block.rs
+++ b/import/src/block.rs
@@ -1,13 +1,13 @@
 use std::io;
 use hash::H32;
 use ser::{Deserializable, Reader, Error as ReaderError};
-use chain;
+use chain::IndexedBlock;
 
 #[derive(Debug, PartialEq)]
 pub struct Block {
 	pub magic: H32,
 	pub block_size: u32,
-	pub block: chain::Block,
+	pub block: IndexedBlock,
 }
 
 impl Deserializable for Block {
diff --git a/miner/src/block_assembler.rs b/miner/src/block_assembler.rs
index eb119947..6e2a5f7e 100644
--- a/miner/src/block_assembler.rs
+++ b/miner/src/block_assembler.rs
@@ -1,7 +1,7 @@
 use std::collections::HashSet;
 use primitives::hash::H256;
-use chain::{OutPoint, TransactionOutput};
-use db::{SharedStore, IndexedTransaction, PreviousTransactionOutputProvider};
+use chain::{OutPoint, TransactionOutput, IndexedTransaction};
+use db::{SharedStore, PreviousTransactionOutputProvider};
 use network::Magic;
 use memory_pool::{MemoryPool, OrderingStrategy, Entry};
 use verification::{work_required, block_reward_satoshi, transaction_sigops};
@@ -278,7 +278,7 @@ impl BlockAssembler {
 
 #[cfg(test)]
 mod tests {
-	use db::IndexedTransaction;
+	use chain::{IndexedTransaction, IndexedTransactionsRef};
 	use verification::constants::{MAX_BLOCK_SIZE, MAX_BLOCK_SIGOPS};
 	use memory_pool::Entry;
 	use super::{SizePolicy, NextStep, FittingTransactionsIterator};
@@ -317,8 +317,8 @@ mod tests {
 	#[test]
 	fn test_fitting_transactions_iterator_no_transactions() {
 		let store: Vec<IndexedTransaction> = Vec::new();
+		let store_ref = IndexedTransactionsRef::new(&store);
 		let entries: Vec<Entry> = Vec::new();
-		let store_ref: &[_] = &store;
 
 		let iter = FittingTransactionsIterator::new(&store_ref, entries.iter(), MAX_BLOCK_SIZE as u32, MAX_BLOCK_SIGOPS as u32, 0, 0);
 		assert!(iter.collect::<Vec<_>>().is_empty());
diff --git a/p2p/src/lib.rs b/p2p/src/lib.rs
index 381b64e3..6f183238 100644
--- a/p2p/src/lib.rs
+++ b/p2p/src/lib.rs
@@ -32,5 +32,5 @@ pub use config::Config;
 pub use net::Config as NetConfig;
 pub use p2p::{P2P, Context};
 pub use event_loop::{event_loop, forever};
-pub use util::{NodeTableError, PeerId, PeerInfo, InternetProtocol};
+pub use util::{NodeTableError, PeerId, PeerInfo, InternetProtocol, Direction};
 pub use protocol::{InboundSyncConnection, InboundSyncConnectionRef, OutboundSyncConnection, OutboundSyncConnectionRef, LocalSyncNode, LocalSyncNodeRef};
diff --git a/p2p/src/net/connections.rs b/p2p/src/net/connections.rs
index c3ed4c17..ed56eb9b 100644
--- a/p2p/src/net/connections.rs
+++ b/p2p/src/net/connections.rs
@@ -35,8 +35,13 @@ impl Connections {
 		self.channels().values().map(|channel| channel.peer_info().address).collect()
 	}
 
+	/// Returns info on every peer
+	pub fn info(&self) -> Vec<PeerInfo> {
+		self.channels().values().map(|channel| channel.peer_info()).collect()
+	}
+
 	/// Returns number of connections.
-	pub fn _count(&self) -> usize {
+	pub fn count(&self) -> usize {
 		self.channels.read().len()
 	}
 
diff --git a/p2p/src/p2p.rs b/p2p/src/p2p.rs
index 6c658f2f..6db84249 100644
--- a/p2p/src/p2p.rs
+++ b/p2p/src/p2p.rs
@@ -386,6 +386,14 @@ impl Context {
 	pub fn create_sync_session(&self, start_height: i32, outbound_connection: OutboundSyncConnectionRef) -> InboundSyncConnectionRef {
 		self.local_sync_node.create_sync_session(start_height, outbound_connection)
 	}
+
+	pub fn connections(&self) -> &Connections {
+		&self.connections
+	}
+
+	pub fn nodes(&self) -> Vec<Node> {
+		self.node_table.read().nodes()
+	}
 }
 
 pub struct P2P {
diff --git a/p2p/src/util/node_table.rs b/p2p/src/util/node_table.rs
index afc8bc64..f197c804 100644
--- a/p2p/src/util/node_table.rs
+++ b/p2p/src/util/node_table.rs
@@ -296,6 +296,11 @@ impl<T> NodeTable<T> where T: Time {
 			.collect()
 	}
 
+	/// Returnes all nodes
+	pub fn nodes(&self) -> Vec<Node> {
+		self.by_addr.iter().map(|(_, n)| n).cloned().collect()
+	}
+
 	/// Returns most recently active nodes.
 	///
 	/// The documenation says:
diff --git a/pbtc/cli.yml b/pbtc/cli.yml
index 2c24665f..86c8d1a3 100644
--- a/pbtc/cli.yml
+++ b/pbtc/cli.yml
@@ -78,3 +78,6 @@ subcommands:
             - PATH:
                 required: true
                 help: Path of the bitcoin core database
+            - skip-verification:
+                long: skip-verification
+                help: Skip blocks verification
diff --git a/pbtc/commands/import.rs b/pbtc/commands/import.rs
index ce5c10ef..ee283d7c 100644
--- a/pbtc/commands/import.rs
+++ b/pbtc/commands/import.rs
@@ -8,9 +8,11 @@ pub fn import(cfg: Config, matches: &ArgMatches) -> Result<(), String> {
 	// TODO: this might be unnecessary here!
 	try!(init_db(&cfg, &db));
 
-	let mut writer = create_sync_blocks_writer(db, cfg.magic);
-
 	let blk_path = matches.value_of("PATH").expect("PATH is required in cli.yml; qed");
+	let skip_verification = matches.is_present("skip-verification");
+
+	let mut writer = create_sync_blocks_writer(db, cfg.magic, !skip_verification);
+
 	let blk_dir = try!(::import::open_blk_dir(blk_path).map_err(|_| "Import directory does not exist".to_owned()));
 	let mut counter = 0;
 	for blk in blk_dir {
@@ -20,7 +22,7 @@ pub fn import(cfg: Config, matches: &ArgMatches) -> Result<(), String> {
 			Ok(_) => {
 				counter += 1;
 				if counter % 1000 == 0 {
-					info!("Imported {} blocks", counter);
+					info!(target: "sync", "Imported {} blocks", counter);
 				}
 			}
 			Err(Error::TooManyOrphanBlocks) => return Err("Too many orphan (unordered) blocks".into()),
diff --git a/rpc/src/v1/helpers/errors.rs b/rpc/src/v1/helpers/errors.rs
index b14f70a5..984b0a27 100644
--- a/rpc/src/v1/helpers/errors.rs
+++ b/rpc/src/v1/helpers/errors.rs
@@ -2,6 +2,7 @@
 
 mod codes {
 	// NOTE [ToDr] Codes from [-32099, -32000]
+	pub const UNKNOWN: i64 = -32000;
 	pub const EXECUTION_ERROR: i64 = -32015;
 	pub const TRANSACTION_NOT_FOUND: i64 = -32096;
 	pub const TRANSACTION_OUTPUT_NOT_FOUND: i64 = -32097;
@@ -97,3 +98,11 @@ pub fn node_not_added() -> Error {
 		data: None,
 	}
 }
+
+pub fn unknown() -> Error {
+	Error {
+		code: ErrorCode::ServerError(codes::UNKNOWN),
+		message: "Unknown error has occurred".into(),
+		data: None,
+	}
+}
diff --git a/rpc/src/v1/impls/blockchain.rs b/rpc/src/v1/impls/blockchain.rs
index 63ae0c16..0063b3af 100644
--- a/rpc/src/v1/impls/blockchain.rs
+++ b/rpc/src/v1/impls/blockchain.rs
@@ -9,7 +9,7 @@ use v1::helpers::errors::{block_not_found, block_at_height_not_found, transactio
 	transaction_output_not_found, transaction_of_side_branch};
 use jsonrpc_macros::Trailing;
 use jsonrpc_core::Error;
-use db;
+use {db, chain};
 use global_script::Script;
 use chain::OutPoint;
 use verification;
@@ -69,7 +69,7 @@ impl BlockChainClientCoreApi for BlockChainClientCore {
 	fn verbose_block(&self, hash: GlobalH256) -> Option<VerboseBlock> {
 		self.storage.block(hash.into())
 			.map(|block| {
-				let block: db::IndexedBlock = block.into();
+				let block: chain::IndexedBlock = block.into();
 				let height = self.storage.block_number(block.hash());
 				let confirmations = match height {
 					Some(block_number) => (self.storage.best_block().expect("genesis block is required").number - block_number + 1) as i64,
diff --git a/rpc/src/v1/impls/network.rs b/rpc/src/v1/impls/network.rs
index 842996c8..01e6b2ae 100644
--- a/rpc/src/v1/impls/network.rs
+++ b/rpc/src/v1/impls/network.rs
@@ -1,8 +1,9 @@
 use std::sync::Arc;
-use std::net::SocketAddr;
+use std::net::{SocketAddr, IpAddr};
 use v1::traits::Network as NetworkRpc;
-use v1::types::AddNodeOperation;
+use v1::types::{AddNodeOperation, NodeInfo};
 use jsonrpc_core::Error;
+use jsonrpc_macros::Trailing;
 use v1::helpers::errors;
 use p2p;
 
@@ -10,6 +11,9 @@ pub trait NetworkApi : Send + Sync + 'static {
 	fn add_node(&self, socket_addr: SocketAddr) -> Result<(), p2p::NodeTableError>;
 	fn remove_node(&self, socket_addr: SocketAddr) -> Result<(), p2p::NodeTableError>;
 	fn connect(&self, socket_addr: SocketAddr);
+	fn node_info(&self, node_addr: IpAddr) -> Result<NodeInfo, p2p::NodeTableError>;
+	fn nodes_info(&self) -> Vec<NodeInfo>;
+	fn connection_count(&self) -> usize;
 }
 
 impl<T> NetworkRpc for NetworkClient<T> where T: NetworkApi {
@@ -29,6 +33,27 @@ impl<T> NetworkRpc for NetworkClient<T> where T: NetworkApi {
 			}
 		}
 	}
+
+	fn node_info(&self, _dns: bool, node_addr: Trailing<String>) -> Result<Vec<NodeInfo>, Error> {
+		Ok(
+			if node_addr.0.is_empty() {
+				self.api.nodes_info()
+			}
+			else {
+				let addr = try!(node_addr.0.parse().map_err(
+					|_| errors::invalid_params("node", "Invalid ip address format, should be ip address (127.0.0.1)")));
+				let node_info = try!(
+					self.api.node_info(addr)
+						.map_err(|_| errors::node_not_added())
+				);
+				vec![node_info]
+			}
+		)
+	}
+
+	fn connection_count(&self) -> Result<usize, Error> {
+		Ok(self.api.connection_count())
+	}
 }
 
 pub struct NetworkClient<T: NetworkApi> {
@@ -65,4 +90,43 @@ impl NetworkApi for NetworkClientCore {
 	fn connect(&self, socket_addr: SocketAddr) {
 		p2p::Context::connect_normal(self.p2p.clone(), socket_addr);
 	}
+
+	fn node_info(&self, node_addr: IpAddr) -> Result<NodeInfo, p2p::NodeTableError> {
+		let exact_node = try!(
+			self.p2p.nodes()
+				.iter()
+				.find(|n| n.address().ip() == node_addr)
+				.cloned()
+				.ok_or(p2p::NodeTableError::NoAddressInTable)
+		);
+
+		let peers: Vec<p2p::PeerInfo> = self.p2p.connections().info()
+			.into_iter()
+			.filter(|p| p.address == exact_node.address()).collect();
+
+		Ok(
+			NodeInfo {
+				addednode: format!("{}", exact_node.address()),
+				connected: !peers.is_empty(),
+				addresses: peers.into_iter().map(|p| p.into()).collect(),
+			}
+		)
+	}
+
+	fn nodes_info(&self) -> Vec<NodeInfo> {
+		let peers: Vec<p2p::PeerInfo> = self.p2p.connections().info();
+
+		self.p2p.nodes().iter().map(|n| {
+			let node_peers: Vec<p2p::PeerInfo> = peers.iter().filter(|p| p.address == n.address()).cloned().collect();
+			NodeInfo {
+				addednode: format!("{}", n.address()),
+				connected: !node_peers.is_empty(),
+				addresses: node_peers.into_iter().map(|p| p.into()).collect(),
+			}
+		}).collect()
+	}
+
+	fn connection_count(&self) -> usize {
+		self.p2p.connections().count()
+	}
 }
diff --git a/rpc/src/v1/traits/network.rs b/rpc/src/v1/traits/network.rs
index c09cf60b..5fcc0004 100644
--- a/rpc/src/v1/traits/network.rs
+++ b/rpc/src/v1/traits/network.rs
@@ -1,14 +1,24 @@
 use jsonrpc_core::Error;
-use v1::types::AddNodeOperation;
+use jsonrpc_macros::Trailing;
+use v1::types::{AddNodeOperation, NodeInfo};
 
 build_rpc_trait! {
 	/// Parity-bitcoin network interface
 	pub trait Network {
-		/// Add/remove/connecto to the node
+		/// Add/remove/connect to the node
 		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "method": "addnode", "params": ["127.0.0.1:8888", "add"], "id":1 }' -H 'content-type: application/json;' http://127.0.0.1:8332/
 		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "method": "addnode", "params": ["127.0.0.1:8888", "remove"], "id":1 }' -H 'content-type: application/json;' http://127.0.0.1:8332/
 		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "method": "addnode", "params": ["127.0.0.1:8888", "onetry"], "id":1 }' -H 'content-type: application/json;' http://127.0.0.1:8332/
 		#[rpc(name = "addnode")]
 		fn add_node(&self, String, AddNodeOperation) -> Result<(), Error>;
+		/// Query node(s) info
+		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "id":"1", "method": "getaddednodeinfo", "params": [true] }' -H 'content-type: application/json;' http://127.0.0.1:8332/
+		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "id":"1", "method": "getaddednodeinfo", "params": [true, "192.168.0.201"] }' -H 'content-type: application/json;' http://127.0.0.1:8332/
+		#[rpc(name = "getaddednodeinfo")]
+		fn node_info(&self, bool, Trailing<String>) -> Result<Vec<NodeInfo>, Error>;
+		/// Query node(s) info
+		/// @curl-example: curl --data-binary '{"jsonrpc": "2.0", "id":"1", "method": "getconnectioncount", "params": [] }' -H 'content-type: application/json;' http://127.0.0.1:8332/
+		#[rpc(name = "getconnectioncount")]
+		fn connection_count(&self) -> Result<usize, Error>;
 	}
 }
diff --git a/rpc/src/v1/types/block_template.rs b/rpc/src/v1/types/block_template.rs
index 706e7516..1e774771 100644
--- a/rpc/src/v1/types/block_template.rs
+++ b/rpc/src/v1/types/block_template.rs
@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 use super::hash::H256;
+use chain;
 use super::transaction::RawTransaction;
-use db;
 use miner;
 
 /// Block template as described in:
@@ -96,8 +96,8 @@ impl From<miner::BlockTemplate> for BlockTemplate {
 	}
 }
 
-impl From<db::IndexedTransaction> for BlockTemplateTransaction {
-	fn from(transaction: db::IndexedTransaction) -> Self {
+impl From<chain::IndexedTransaction> for BlockTemplateTransaction {
+	fn from(transaction: chain::IndexedTransaction) -> Self {
 		use ser::serialize;
 		let serialize = serialize(&transaction.raw);
 		BlockTemplateTransaction {
diff --git a/rpc/src/v1/types/mod.rs.in b/rpc/src/v1/types/mod.rs.in
index 3012cd1e..5d1fe7b6 100644
--- a/rpc/src/v1/types/mod.rs.in
+++ b/rpc/src/v1/types/mod.rs.in
@@ -26,4 +26,4 @@ pub use self::transaction::{RawTransaction, Transaction, TransactionInput, Trans
 	TransactionInputScript, TransactionOutputScript, SignedTransactionInput, GetRawTransactionResponse,
 	SignedTransactionOutput, TransactionOutputs};
 pub use self::uint::U256;
-pub use self::nodes::AddNodeOperation;
+pub use self::nodes::{AddNodeOperation, NodeInfo};
diff --git a/rpc/src/v1/types/nodes.rs b/rpc/src/v1/types/nodes.rs
index 0ba9ff50..cce26540 100644
--- a/rpc/src/v1/types/nodes.rs
+++ b/rpc/src/v1/types/nodes.rs
@@ -1,4 +1,5 @@
-use serde::{Deserialize, Deserializer};
+use serde::{Serialize, Serializer, Deserialize, Deserializer};
+use p2p::{Direction, PeerInfo};
 
 #[derive(Debug, PartialEq)]
 pub enum AddNodeOperation {
@@ -29,3 +30,42 @@ impl Deserialize for AddNodeOperation {
 		deserializer.deserialize(DummyVisitor)
 	}
 }
+
+#[derive(Serialize)]
+pub struct NodeInfoAddress {
+	address: String,
+	connected: NodeInfoAddressConnectionType,
+}
+
+impl From<PeerInfo> for NodeInfoAddress {
+	fn from(info: PeerInfo) -> Self {
+		NodeInfoAddress {
+			address: format!("{}", info.address),
+			connected: match info.direction {
+				Direction::Inbound => NodeInfoAddressConnectionType::Inbound,
+				Direction::Outbound => NodeInfoAddressConnectionType::Outbound,
+			},
+		}
+	}
+}
+
+#[derive(Serialize)]
+pub struct NodeInfo {
+	pub addednode: String,
+	pub connected: bool,
+	pub addresses: Vec<NodeInfoAddress>,
+}
+
+pub enum NodeInfoAddressConnectionType {
+	Inbound,
+	Outbound,
+}
+
+impl Serialize for NodeInfoAddressConnectionType {
+	fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error> where S: Serializer {
+		match *self {
+			NodeInfoAddressConnectionType::Inbound => "inbound".serialize(serializer),
+			NodeInfoAddressConnectionType::Outbound => "outbound".serialize(serializer),
+		}
+	}
+}
diff --git a/script/src/interpreter.rs b/script/src/interpreter.rs
index c73e58ec..a361bbca 100644
--- a/script/src/interpreter.rs
+++ b/script/src/interpreter.rs
@@ -1,7 +1,7 @@
 use std::{cmp, mem};
 use bytes::Bytes;
 use keys::{Signature, Public};
-use chain::SEQUENCE_LOCKTIME_DISABLE_FLAG;
+use chain::constants::SEQUENCE_LOCKTIME_DISABLE_FLAG;
 use crypto::{sha1, sha256, dhash160, dhash256, ripemd160};
 use {
 	script, Script, Num, VerificationFlags, Opcode, Error,
diff --git a/script/src/verify.rs b/script/src/verify.rs
index 6ea02240..d3a5bffa 100644
--- a/script/src/verify.rs
+++ b/script/src/verify.rs
@@ -1,7 +1,7 @@
 use keys::{Public, Signature};
-use chain::{
-	self, SEQUENCE_FINAL, SEQUENCE_LOCKTIME_DISABLE_FLAG,
-	SEQUENCE_LOCKTIME_MASK, SEQUENCE_LOCKTIME_TYPE_FLAG
+use chain::constants::{
+	SEQUENCE_FINAL, SEQUENCE_LOCKTIME_DISABLE_FLAG,
+	SEQUENCE_LOCKTIME_MASK, SEQUENCE_LOCKTIME_TYPE_FLAG, LOCKTIME_THRESHOLD
 };
 use {SignatureVersion, Script, TransactionInputSigner, Num};
 
@@ -64,8 +64,8 @@ impl SignatureChecker for TransactionSignatureChecker {
 		// the nLockTime in the transaction.
 		let lock_time_u32: u32 = lock_time.into();
 		if !(
-			(self.signer.lock_time < chain::LOCKTIME_THRESHOLD && lock_time_u32 < chain::LOCKTIME_THRESHOLD) ||
-			(self.signer.lock_time >= chain::LOCKTIME_THRESHOLD && lock_time_u32 >= chain::LOCKTIME_THRESHOLD)
+			(self.signer.lock_time < LOCKTIME_THRESHOLD && lock_time_u32 < LOCKTIME_THRESHOLD) ||
+			(self.signer.lock_time >= LOCKTIME_THRESHOLD && lock_time_u32 >= LOCKTIME_THRESHOLD)
 		) {
 			return false;
 		}
diff --git a/serialization/src/reader.rs b/serialization/src/reader.rs
index 51dacb61..653a99b5 100644
--- a/serialization/src/reader.rs
+++ b/serialization/src/reader.rs
@@ -84,6 +84,11 @@ impl<R> Reader<R> where R: io::Read {
 		T::deserialize(self)
 	}
 
+	pub fn read_with_proxy<T, F>(&mut self, proxy: F) -> Result<T, Error> where T: Deserializable, F: FnMut(&[u8]) {
+		let mut reader = Reader::from_read(Proxy::new(self, proxy));
+		T::deserialize(&mut reader)
+	}
+
 	pub fn read_slice(&mut self, bytes: &mut [u8]) -> Result<(), Error> {
 		io::Read::read_exact(self, bytes).map_err(|_| Error::UnexpectedEnd)
 	}
@@ -148,3 +153,26 @@ impl<R, T> Iterator for ReadIterator<R, T> where R: io::Read, T: Deserializable
 		}
 	}
 }
+
+struct Proxy<F, T> {
+	from: F,
+	to: T,
+}
+
+impl<F, T> Proxy<F, T> {
+	fn new(from: F, to: T) -> Self {
+		Proxy {
+			from: from,
+			to: to,
+		}
+	}
+}
+
+impl<F, T> io::Read for Proxy<F, T> where F: io::Read, T: FnMut(&[u8]) {
+	fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
+		let len = try!(io::Read::read(&mut self.from, buf));
+		let to = &mut self.to;
+		to(&buf[..len]);
+		Ok(len)
+	}
+}
diff --git a/sync/src/blocks_writer.rs b/sync/src/blocks_writer.rs
index 489fcdba..21c35d99 100644
--- a/sync/src/blocks_writer.rs
+++ b/sync/src/blocks_writer.rs
@@ -17,6 +17,7 @@ pub struct BlocksWriter {
 	orphaned_blocks_pool: OrphanBlocksPool,
 	verifier: SyncVerifier<BlocksWriterSink>,
 	sink: Arc<BlocksWriterSinkData>,
+	verification: bool,
 }
 
 struct BlocksWriterSink {
@@ -29,7 +30,7 @@ struct BlocksWriterSinkData {
 }
 
 impl BlocksWriter {
-	pub fn new(storage: db::SharedStore, network: Magic) -> BlocksWriter {
+	pub fn new(storage: db::SharedStore, network: Magic, verification: bool) -> BlocksWriter {
 		let sink_data = Arc::new(BlocksWriterSinkData::new(storage.clone()));
 		let sink = Arc::new(BlocksWriterSink::new(sink_data.clone()));
 		let verifier = SyncVerifier::new(network, storage.clone(), sink);
@@ -38,18 +39,18 @@ impl BlocksWriter {
 			orphaned_blocks_pool: OrphanBlocksPool::new(),
 			verifier: verifier,
 			sink: sink_data,
+			verification: verification,
 		}
 	}
 
-	pub fn append_block(&mut self, block: chain::Block) -> Result<(), Error> {
-		let indexed_block: db::IndexedBlock = block.into();
+	pub fn append_block(&mut self, block: chain::IndexedBlock) -> Result<(), Error> {
 		// do not append block if it is already there
-		if self.storage.contains_block(db::BlockRef::Hash(indexed_block.hash().clone())) {
+		if self.storage.contains_block(db::BlockRef::Hash(block.hash().clone())) {
 			return Ok(());
 		}
 		// verify && insert only if parent block is already in the storage
-		if !self.storage.contains_block(db::BlockRef::Hash(indexed_block.header.raw.previous_header_hash.clone())) {
-			self.orphaned_blocks_pool.insert_orphaned_block(indexed_block.hash().clone(), indexed_block);
+		if !self.storage.contains_block(db::BlockRef::Hash(block.header.raw.previous_header_hash.clone())) {
+			self.orphaned_blocks_pool.insert_orphaned_block(block.hash().clone(), block);
 			// we can't hold many orphaned blocks in memory during import
 			if self.orphaned_blocks_pool.len() > MAX_ORPHANED_BLOCKS {
 				return Err(Error::TooManyOrphanBlocks);
@@ -58,13 +59,17 @@ impl BlocksWriter {
 		}
 
 		// verify && insert block && all its orphan children
-		let mut verification_queue: VecDeque<db::IndexedBlock> = self.orphaned_blocks_pool.remove_blocks_for_parent(indexed_block.hash()).into_iter().map(|(_, b)| b).collect();
-		verification_queue.push_front(indexed_block);
+		let mut verification_queue: VecDeque<chain::IndexedBlock> = self.orphaned_blocks_pool.remove_blocks_for_parent(block.hash()).into_iter().map(|(_, b)| b).collect();
+		verification_queue.push_front(block);
 		while let Some(block) = verification_queue.pop_front() {
-			self.verifier.verify_block(block);
+			if self.verification {
+				self.verifier.verify_block(block);
 
-			if let Some(err) = self.sink.error() {
-				return Err(err);
+				if let Some(err) = self.sink.error() {
+					return Err(err);
+				}
+			} else {
+				try!(self.storage.insert_indexed_block(&block).map_err(Error::Database));
 			}
 		}
 
@@ -97,7 +102,7 @@ impl VerificationSink for BlocksWriterSink {
 }
 
 impl BlockVerificationSink for BlocksWriterSink {
-	fn on_block_verification_success(&self, block: db::IndexedBlock) -> Option<Vec<VerificationTask>> {
+	fn on_block_verification_success(&self, block: chain::IndexedBlock) -> Option<Vec<VerificationTask>> {
 		if let Err(err) = self.data.storage.insert_indexed_block(&block) {
 			*self.data.err.lock() = Some(Error::Database(err));
 		}
@@ -132,8 +137,8 @@ mod tests {
 	#[test]
 	fn blocks_writer_appends_blocks() {
 		let db = Arc::new(db::TestStorage::with_genesis_block());
-		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet);
-		blocks_target.append_block(test_data::block_h1()).expect("Expecting no error");
+		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet, true);
+		blocks_target.append_block(test_data::block_h1().into()).expect("Expecting no error");
 		assert_eq!(db.best_block().expect("Block is inserted").number, 1);
 	}
 
@@ -141,9 +146,9 @@ mod tests {
 	fn blocks_writer_verification_error() {
 		let db = Arc::new(db::TestStorage::with_genesis_block());
 		let blocks = test_data::build_n_empty_blocks_from_genesis((MAX_ORPHANED_BLOCKS + 2) as u32, 1);
-		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet);
+		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet, true);
 		for (index, block) in blocks.into_iter().skip(1).enumerate() {
-			match blocks_target.append_block(block) {
+			match blocks_target.append_block(block.into()) {
 				Err(Error::TooManyOrphanBlocks) if index == MAX_ORPHANED_BLOCKS => (),
 				Ok(_) if index != MAX_ORPHANED_BLOCKS => (),
 				_ => panic!("unexpected"),
@@ -155,12 +160,12 @@ mod tests {
 	#[test]
 	fn blocks_writer_out_of_order_block() {
 		let db = Arc::new(db::TestStorage::with_genesis_block());
-		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet);
+		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet, true);
 
 		let wrong_block = test_data::block_builder()
 			.header().parent(test_data::genesis().hash()).build()
 		.build();
-		match blocks_target.append_block(wrong_block).unwrap_err() {
+		match blocks_target.append_block(wrong_block.into()).unwrap_err() {
 			Error::Verification(_) => (),
 			_ => panic!("Unexpected error"),
 		};
@@ -170,12 +175,12 @@ mod tests {
 	#[test]
 	fn blocks_writer_append_to_existing_db() {
 		let db = Arc::new(db::TestStorage::with_genesis_block());
-		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet);
+		let mut blocks_target = BlocksWriter::new(db.clone(), Magic::Testnet, true);
 
-		assert!(blocks_target.append_block(test_data::genesis()).is_ok());
+		assert!(blocks_target.append_block(test_data::genesis().into()).is_ok());
 		assert_eq!(db.best_block().expect("Block is inserted").number, 0);
 
-		assert!(blocks_target.append_block(test_data::block_h1()).is_ok());
+		assert!(blocks_target.append_block(test_data::block_h1().into()).is_ok());
 		assert_eq!(db.best_block().expect("Block is inserted").number, 1);
 	}
 }
diff --git a/sync/src/compact_block_builder.rs b/sync/src/compact_block_builder.rs
index 3084f337..217b4bc1 100644
--- a/sync/src/compact_block_builder.rs
+++ b/sync/src/compact_block_builder.rs
@@ -2,8 +2,7 @@ use std::collections::HashSet;
 use rand::{thread_rng, Rng};
 use bitcrypto::{sha256, siphash24};
 use byteorder::{LittleEndian, ByteOrder};
-use chain::{BlockHeader, ShortTransactionID};
-use db::IndexedBlock;
+use chain::{BlockHeader, ShortTransactionID, IndexedBlock};
 use message::common::{BlockHeaderAndIDs, PrefilledTransaction};
 use primitives::hash::H256;
 use ser::{Stream, Serializable};
diff --git a/sync/src/lib.rs b/sync/src/lib.rs
index aebaefbd..96b53144 100644
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@@ -63,8 +63,8 @@ pub enum Error {
 }
 
 /// Create blocks writer.
-pub fn create_sync_blocks_writer(db: db::SharedStore, network: Magic) -> blocks_writer::BlocksWriter {
-	blocks_writer::BlocksWriter::new(db, network)
+pub fn create_sync_blocks_writer(db: db::SharedStore, network: Magic, verification: bool) -> blocks_writer::BlocksWriter {
+	blocks_writer::BlocksWriter::new(db, network, verification)
 }
 
 /// Creates local sync node for given `db`
diff --git a/sync/src/orphan_blocks_pool.rs b/sync/src/orphan_blocks_pool.rs
index 4e2e3dab..37cfcfc1 100644
--- a/sync/src/orphan_blocks_pool.rs
+++ b/sync/src/orphan_blocks_pool.rs
@@ -3,7 +3,7 @@ use std::collections::hash_map::Entry;
 use linked_hash_map::LinkedHashMap;
 use time;
 use primitives::hash::H256;
-use db::IndexedBlock;
+use chain::IndexedBlock;
 
 #[derive(Debug)]
 /// Storage for blocks, for which we have no parent yet.
diff --git a/sync/src/synchronization_chain.rs b/sync/src/synchronization_chain.rs
index 28a1ea4d..e018378f 100644
--- a/sync/src/synchronization_chain.rs
+++ b/sync/src/synchronization_chain.rs
@@ -3,8 +3,8 @@ use std::sync::Arc;
 use std::collections::{VecDeque, HashSet};
 use linked_hash_map::LinkedHashMap;
 use parking_lot::RwLock;
-use chain::{BlockHeader, Transaction};
-use db::{self, IndexedBlock};
+use chain::{BlockHeader, Transaction, IndexedBlock};
+use db;
 use best_headers_chain::{BestHeadersChain, Information as BestHeadersInformation};
 use primitives::bytes::Bytes;
 use primitives::hash::H256;
diff --git a/sync/src/synchronization_client.rs b/sync/src/synchronization_client.rs
index 9bf722cf..2dfd8db8 100644
--- a/sync/src/synchronization_client.rs
+++ b/sync/src/synchronization_client.rs
@@ -7,8 +7,8 @@ use futures::{BoxFuture, Future, finished};
 use futures::stream::Stream;
 use tokio_core::reactor::{Handle, Interval};
 use futures_cpupool::CpuPool;
-use db::{self, IndexedBlock, BlockHeaderProvider, BlockRef};
-use chain::{BlockHeader, Transaction};
+use db::{self, BlockHeaderProvider, BlockRef};
+use chain::{BlockHeader, Transaction, IndexedBlock};
 use message::types;
 use message::common::{InventoryVector, InventoryType};
 use primitives::hash::H256;
@@ -1312,7 +1312,7 @@ impl<T> SynchronizationClientCore<T> where T: TaskExecutor {
 							}
 						},
 						BlockAnnouncementType::SendCompactBlock => {
-							let indexed_blocks: Vec<db::IndexedBlock> = {
+							let indexed_blocks: Vec<IndexedBlock> = {
 								let chain = self.chain.read();
 								new_blocks_hashes.iter()
 									.filter_map(|h| chain.storage().block(db::BlockRef::Hash(h.clone())))
diff --git a/sync/src/synchronization_verifier.rs b/sync/src/synchronization_verifier.rs
index c1c9492a..5c71eae9 100644
--- a/sync/src/synchronization_verifier.rs
+++ b/sync/src/synchronization_verifier.rs
@@ -2,7 +2,7 @@ use std::thread;
 use std::collections::{VecDeque, HashSet};
 use std::sync::Arc;
 use std::sync::mpsc::{channel, Sender, Receiver};
-use chain::{Transaction, OutPoint, TransactionOutput};
+use chain::{Transaction, OutPoint, TransactionOutput, IndexedBlock};
 use network::Magic;
 use miner::{HashedOutPoint, DoubleSpendCheckResult};
 use primitives::hash::H256;
diff --git a/verification/src/canon.rs b/verification/src/canon.rs
index 9b3e379a..dd8f94ff 100644
--- a/verification/src/canon.rs
+++ b/verification/src/canon.rs
@@ -1,6 +1,6 @@
 use std::ops;
 use primitives::hash::H256;
-use db::{IndexedBlock, IndexedTransaction, IndexedBlockHeader};
+use chain::{IndexedBlock, IndexedTransaction, IndexedBlockHeader};
 
 /// Blocks whose parents are known to be in the chain
 #[derive(Clone, Copy)]
diff --git a/verification/src/chain_verifier.rs b/verification/src/chain_verifier.rs
index 3fa700e3..8501a9dc 100644
--- a/verification/src/chain_verifier.rs
+++ b/verification/src/chain_verifier.rs
@@ -1,10 +1,10 @@
 //! Bitcoin chain verifier
 
 use hash::H256;
-use db::{self, IndexedBlockHeader, BlockLocation, PreviousTransactionOutputProvider, BlockHeaderProvider, TransactionOutputObserver};
+use chain::{IndexedBlock, IndexedBlockHeader, BlockHeader, Transaction};
+use db::{BlockLocation, SharedStore, PreviousTransactionOutputProvider, BlockHeaderProvider, TransactionOutputObserver};
 use network::Magic;
 use error::{Error, TransactionError};
-use {Verify, chain};
 use canon::{CanonBlock, CanonTransaction};
 use duplex_store::{DuplexTransactionOutputProvider, NoopStore};
 use verify_chain::ChainVerifier;
@@ -12,6 +12,7 @@ use verify_header::HeaderVerifier;
 use verify_transaction::MemoryPoolTransactionVerifier;
 use accept_chain::ChainAcceptor;
 use accept_transaction::MemoryPoolTransactionAcceptor;
+use Verify;
 
 #[derive(PartialEq, Debug)]
 /// Block verification chain
@@ -28,13 +29,13 @@ pub enum Chain {
 pub type VerificationResult = Result<Chain, Error>;
 
 pub struct BackwardsCompatibleChainVerifier {
-	store: db::SharedStore,
+	store: SharedStore,
 	skip_pow: bool,
 	network: Magic,
 }
 
 impl BackwardsCompatibleChainVerifier {
-	pub fn new(store: db::SharedStore, network: Magic) -> Self {
+	pub fn new(store: SharedStore, network: Magic) -> Self {
 		BackwardsCompatibleChainVerifier {
 			store: store,
 			skip_pow: false,
@@ -48,7 +49,7 @@ impl BackwardsCompatibleChainVerifier {
 		self
 	}
 
-	fn verify_block(&self, block: &db::IndexedBlock) -> VerificationResult {
+	fn verify_block(&self, block: &IndexedBlock) -> VerificationResult {
 		let current_time = ::time::get_time().sec as u32;
 		// first run pre-verification
 		let chain_verifier = ChainVerifier::new(block, self.network, current_time);
@@ -77,7 +78,7 @@ impl BackwardsCompatibleChainVerifier {
 		&self,
 		_block_header_provider: &BlockHeaderProvider,
 		hash: &H256,
-		header: &chain::BlockHeader
+		header: &BlockHeader
 	) -> Result<(), Error> {
 		// let's do only preverifcation
 		// TODO: full verification
@@ -92,7 +93,7 @@ impl BackwardsCompatibleChainVerifier {
 		prevout_provider: &T,
 		height: u32,
 		time: u32,
-		transaction: &chain::Transaction,
+		transaction: &Transaction,
 	) -> Result<(), TransactionError> where T: PreviousTransactionOutputProvider + TransactionOutputObserver {
 		let indexed_tx = transaction.clone().into();
 		// let's do preverification first
@@ -117,7 +118,7 @@ impl BackwardsCompatibleChainVerifier {
 }
 
 impl Verify for BackwardsCompatibleChainVerifier {
-	fn verify(&self, block: &db::IndexedBlock) -> VerificationResult {
+	fn verify(&self, block: &IndexedBlock) -> VerificationResult {
 		let result = self.verify_block(block);
 		trace!(
 			target: "verification", "Block {} (transactions: {}) verification finished. Result {:?}",
@@ -132,7 +133,8 @@ impl Verify for BackwardsCompatibleChainVerifier {
 #[cfg(test)]
 mod tests {
 	use std::sync::Arc;
-	use db::{TestStorage, Storage, Store, BlockStapler, IndexedBlock};
+	use chain::IndexedBlock;
+	use db::{TestStorage, Storage, Store, BlockStapler};
 	use network::Magic;
 	use devtools::RandomTempPath;
 	use {script, test_data};
diff --git a/verification/src/lib.rs b/verification/src/lib.rs
index a5db9899..91e40b72 100644
--- a/verification/src/lib.rs
+++ b/verification/src/lib.rs
@@ -112,5 +112,5 @@ pub use work::{work_required, is_valid_proof_of_work, is_valid_proof_of_work_has
 
 /// Interface for block verification
 pub trait Verify : Send + Sync {
-	fn verify(&self, block: &db::IndexedBlock) -> VerificationResult;
+	fn verify(&self, block: &chain::IndexedBlock) -> VerificationResult;
 }
diff --git a/verification/src/verify_block.rs b/verification/src/verify_block.rs
index cb8937c0..9672a272 100644
--- a/verification/src/verify_block.rs
+++ b/verification/src/verify_block.rs
@@ -1,5 +1,5 @@
 use std::collections::HashSet;
-use db::IndexedBlock;
+use chain::IndexedBlock;
 use sigops::transaction_sigops;
 use duplex_store::NoopStore;
 use error::{Error, TransactionError};
diff --git a/verification/src/verify_chain.rs b/verification/src/verify_chain.rs
index 84c663cd..bce19e14 100644
--- a/verification/src/verify_chain.rs
+++ b/verification/src/verify_chain.rs
@@ -1,5 +1,5 @@
 use rayon::prelude::{IntoParallelRefIterator, IndexedParallelIterator, ParallelIterator};
-use db::IndexedBlock;
+use chain::IndexedBlock;
 use network::Magic;
 use error::Error;
 use verify_block::BlockVerifier;
diff --git a/verification/src/verify_header.rs b/verification/src/verify_header.rs
index f71a0d6f..d8d05191 100644
--- a/verification/src/verify_header.rs
+++ b/verification/src/verify_header.rs
@@ -1,5 +1,5 @@
 use primitives::compact::Compact;
-use db::IndexedBlockHeader;
+use chain::IndexedBlockHeader;
 use network::Magic;
 use work::is_valid_proof_of_work;
 use error::Error;
diff --git a/verification/src/verify_transaction.rs b/verification/src/verify_transaction.rs
index 49647e40..9e3f7a34 100644
--- a/verification/src/verify_transaction.rs
+++ b/verification/src/verify_transaction.rs
@@ -1,6 +1,6 @@
 use std::ops;
 use serialization::Serializable;
-use db::IndexedTransaction;
+use chain::IndexedTransaction;
 use duplex_store::NoopStore;
 use sigops::transaction_sigops;
 use error::TransactionError;