diff --git a/alfis.cfg b/alfis.cfg
index 4de36d3..771681d 100644
--- a/alfis.cfg
+++ b/alfis.cfg
@@ -2,7 +2,7 @@
     "chain_name": "test",
     "origin": "",
     "version": 0,
-    "key_file": "default3.key",
+    "key_file": "default.key",
     "listen": "127.0.0.1:4244",
     "public": true,
     "peers": [
diff --git a/src/blockchain/block.rs b/src/blockchain/block.rs
index 5a4f0ef..be33495 100644
--- a/src/blockchain/block.rs
+++ b/src/blockchain/block.rs
@@ -4,10 +4,7 @@ extern crate num_bigint;
 extern crate num_traits;
 
 use std::fmt::Debug;
-use chrono::Utc;
 use serde::{Serialize, Deserialize};
-use num_bigint::BigUint;
-use num_traits::One;
 use crypto::sha2::Sha256;
 use crypto::digest::Digest;
 use crate::keys::Bytes;
diff --git a/src/blockchain/blockchain.rs b/src/blockchain/blockchain.rs
index e5e0b2b..58f12c0 100644
--- a/src/blockchain/blockchain.rs
+++ b/src/blockchain/blockchain.rs
@@ -1,12 +1,11 @@
-use chrono::Utc;
-use sqlite::{Connection, Error, Readable, State, Statement};
+use sqlite::{Connection, State, Statement};
 
-use crate::{Block, Bytes, Keystore, Transaction};
+use crate::{Block, Bytes, Keystore, Transaction, Settings};
 
 const DB_NAME: &str = "blockchain.db";
 
 pub struct Blockchain {
-    origin: String,
+    origin: Bytes,
     pub version: u32,
     pub blocks: Vec<Block>,
     last_block: Option<Block>,
@@ -14,7 +13,10 @@ pub struct Blockchain {
 }
 
 impl Blockchain {
-    pub fn new(origin: String, version: u32) -> Self {
+    pub fn new(settings: &Settings) -> Self {
+        let origin = settings.get_origin();
+        let version = settings.version;
+
         let db = sqlite::open(DB_NAME).expect("Unable to open blockchain DB");
         let mut blockchain = Blockchain{ origin, version, blocks: Vec::new(), last_block: None, db};
         blockchain.init_db();
@@ -59,62 +61,65 @@ impl Blockchain {
         }
     }
 
-    pub fn add_block(&mut self, block: Block) {
-        if self.check_block(&block, &self.last_block) {
-            println!("Adding block:\n{:?}", &block);
-            self.blocks.push(block.clone());
-            self.last_block = Some(block.clone());
-            let transaction = block.transaction.clone();
+    pub fn add_block(&mut self, block: Block) -> Result<(), &str> {
+        if !self.check_block(&block, &self.last_block) {
+            println!("Bad block found, ignoring:\n{:?}", &block);
+            return Err("Bad block found, ignoring");
+        }
+        println!("Adding block:\n{:?}", &block);
+        self.blocks.push(block.clone());
+        self.last_block = Some(block.clone());
+        let transaction = block.transaction.clone();
 
-            {
-                // Adding block to DB
-                let mut statement = self.db.prepare("INSERT INTO blocks (\
+        {
+            // Adding block to DB
+            let mut statement = self.db.prepare("INSERT INTO blocks (\
                     id, timestamp, version, difficulty, random,\
                     nonce, 'transaction', prev_block_hash, hash)\
                     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?);").unwrap();
-                statement.bind(1, block.index as i64);
-                statement.bind(2, block.timestamp as i64);
-                statement.bind(3, block.version as i64);
-                statement.bind(4, block.difficulty as i64);
-                statement.bind(5, block.random as i64);
-                statement.bind(6, block.nonce as i64);
-                match &transaction {
-                    None => { statement.bind(7, ""); }
-                    Some(transaction) => {
-                        statement.bind(7, transaction.to_string().as_ref() as &str);
-                    }
-                }
-                statement.bind(8, block.prev_block_hash.as_bytes());
-                statement.bind(9, block.hash.as_bytes());
-                statement.next().expect("Error adding block to DB");
-            }
-
+            statement.bind(1, block.index as i64).expect("Error in bind");
+            statement.bind(2, block.timestamp as i64).expect("Error in bind");
+            statement.bind(3, block.version as i64).expect("Error in bind");
+            statement.bind(4, block.difficulty as i64).expect("Error in bind");
+            statement.bind(5, block.random as i64).expect("Error in bind");
+            statement.bind(6, block.nonce as i64).expect("Error in bind");
             match &transaction {
-                None => {}
+                None => { statement.bind(7, "").expect("Error in bind"); }
                 Some(transaction) => {
-                    self.add_transaction(transaction);
+                    statement.bind(7, transaction.to_string().as_ref() as &str).expect("Error in bind");
                 }
             }
-        } else {
-            println!("Bad block found, ignoring:\n{:?}", &block);
+            statement.bind(8, block.prev_block_hash.as_bytes()).expect("Error in bind");
+            statement.bind(9, block.hash.as_bytes()).expect("Error in bind");
+            statement.next().expect("Error adding block to DB");
+        }
+
+        match &transaction {
+            None => {
+                Err("Error adding transaction!")
+            }
+            Some(transaction) => {
+                self.add_transaction(transaction);
+                Ok(())
+            }
         }
     }
 
     fn add_transaction(&mut self, t: &Transaction) {
         let mut statement = self.db.prepare("INSERT INTO transactions (identity, confirmation, method, data, pub_key, signature) VALUES (?, ?, ?, ?, ?, ?)").unwrap();
-        statement.bind(1, t.identity.as_bytes());
-        statement.bind(2, t.confirmation.as_bytes());
-        statement.bind(3, t.method.as_ref() as &str);
-        statement.bind(4, t.data.as_ref() as &str);
-        statement.bind(5, t.pub_key.as_bytes());
-        statement.bind(6, t.signature.as_bytes());
+        statement.bind(1, t.identity.as_bytes()).expect("Error in bind");
+        statement.bind(2, t.confirmation.as_bytes()).expect("Error in bind");
+        statement.bind(3, t.method.as_ref() as &str).expect("Error in bind");
+        statement.bind(4, t.data.as_ref() as &str).expect("Error in bind");
+        statement.bind(5, t.pub_key.as_bytes()).expect("Error in bind");
+        statement.bind(6, t.signature.as_bytes()).expect("Error in bind");
         statement.next().expect("Error adding transaction to DB");
     }
 
     pub fn get_block(&self, index: u64) -> Option<Block> {
         match self.db.prepare("SELECT * FROM blocks WHERE id=? LIMIT 1;") {
             Ok(mut statement) => {
-                statement.bind(1, index as i64);
+                statement.bind(1, index as i64).expect("Error in bind");
                 while statement.next().unwrap() == State::Row {
                     return match Self::get_block_from_statement(&mut statement) {
                         None => {
@@ -142,7 +147,7 @@ impl Blockchain {
         }
         let identity_hash = Transaction::hash_identity(domain);
         let mut statement = self.db.prepare("SELECT pub_key FROM transactions WHERE identity = ? ORDER BY id DESC LIMIT 1;").unwrap();
-        statement.bind(1, identity_hash.as_bytes());
+        statement.bind(1, identity_hash.as_bytes()).expect("Error in bind");
         while let State::Row = statement.next().unwrap() {
             let pub_key = Bytes::from_bytes(statement.read::<Vec<u8>>(0).unwrap().as_slice());
             if !pub_key.eq(&keystore.get_public()) {
@@ -159,7 +164,7 @@ impl Blockchain {
             // Checking for available zone, for this domain
             let identity_hash = Transaction::hash_identity(parts.first().unwrap());
             let mut statement = self.db.prepare("SELECT identity FROM transactions WHERE identity = ? ORDER BY id DESC LIMIT 1;").unwrap();
-            statement.bind(1, identity_hash.as_bytes());
+            statement.bind(1, identity_hash.as_bytes()).expect("Error in bind");
             while let State::Row = statement.next().unwrap() {
                 // If there is such a zone
                 return true;
@@ -196,15 +201,36 @@ impl Blockchain {
     }*/
 
     fn check_block(&self, block: &Block, prev_block: &Option<Block>) -> bool {
-        // TODO check if it is already stored, or its height is more than we need
-        if !Self::check_block_hash(block) {
+        if !check_block_hash(block) {
+            println!("{:?} has wrong hash! Ignoring!", &block);
             return false;
         }
-        if prev_block.is_none() {
-            return true;
+        // TODO make transaction not Optional
+        let transaction = block.transaction.as_ref().unwrap();
+        if !check_transaction_signature(&transaction) {
+            println!("{:?} has wrong signature! Ignoring block!", &transaction);
+            return false;
         }
+        match prev_block {
+            None => {
+                if block.index != 0 {
+                    return false;
+                }
 
-        return block.prev_block_hash == prev_block.as_ref().unwrap().hash;
+                if self.origin.is_zero() && block.index > 0 {
+                    panic!("Error adding block {} without origin! Please, fill in origin in config!", block.index);
+                }
+
+                self.origin.is_zero() || block.hash.eq(&self.origin)
+            }
+            Some(prev) => {
+                if block.index != prev.index + 1 {
+                    println!("Discarding block with index {} as not needed now", block.index);
+                    return false;
+                }
+                block.prev_block_hash.eq(&prev.hash)
+            }
+        }
     }
 
     fn get_block_from_statement(statement: &mut Statement) -> Option<Block> {
@@ -219,12 +245,18 @@ impl Blockchain {
         let hash = Bytes::from_bytes(statement.read::<Vec<u8>>(8).unwrap().as_slice());
         Some(Block::from_all_params(index, timestamp, version, difficulty, random, nonce, prev_block_hash, hash, transaction))
     }
-
-    pub fn check_block_hash(block: &Block) -> bool {
-        // We need to clear Hash value to rehash it without it for check :(
-        let mut copy: Block = block.clone();
-        copy.hash = Bytes::default();
-        let data = serde_json::to_string(&copy).unwrap();
-        Block::hash(data.as_bytes()) == block.hash
-    }
+}
+
+pub fn check_block_hash(block: &Block) -> bool {
+    let mut copy: Block = block.clone();
+    copy.hash = Bytes::default();
+    let data = serde_json::to_string(&copy).unwrap();
+    Block::hash(data.as_bytes()) == block.hash
+}
+
+pub fn check_transaction_signature(transaction: &Transaction) -> bool {
+    let mut copy = transaction.clone();
+    copy.signature = Bytes::zero64();
+    let data = copy.get_bytes();
+    Keystore::check(data.as_slice(), copy.pub_key.as_bytes(), transaction.signature.as_bytes())
 }
diff --git a/src/blockchain/transaction.rs b/src/blockchain/transaction.rs
index 8d623e7..1d12e43 100644
--- a/src/blockchain/transaction.rs
+++ b/src/blockchain/transaction.rs
@@ -85,12 +85,12 @@ impl fmt::Debug for Transaction {
 impl Serialize for Transaction {
     fn serialize<S>(&self, serializer: S) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error> where S: Serializer {
         let mut structure = serializer.serialize_struct("Transaction", 6).unwrap();
-        structure.serialize_field("identity", &self.identity);
-        structure.serialize_field("confirmation", &self.confirmation);
-        structure.serialize_field("method", &self.method);
-        structure.serialize_field("data", &self.data);
-        structure.serialize_field("pub_key", &self.pub_key);
-        structure.serialize_field("signature", &self.signature);
+        structure.serialize_field("identity", &self.identity)?;
+        structure.serialize_field("confirmation", &self.confirmation)?;
+        structure.serialize_field("method", &self.method)?;
+        structure.serialize_field("data", &self.data)?;
+        structure.serialize_field("pub_key", &self.pub_key)?;
+        structure.serialize_field("signature", &self.signature)?;
         structure.end()
     }
 }
\ No newline at end of file
diff --git a/src/context.rs b/src/context.rs
index 4fe0354..8e2b21f 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1,8 +1,6 @@
 use crate::{Keystore, Blockchain, Bus, Bytes};
 use crate::event::Event;
-use std::collections::HashMap;
-use serde::{Serialize, Deserialize, Serializer, Deserializer};
-use serde::de::Error;
+use serde::{Serialize, Deserialize};
 use std::fs::File;
 use std::io::Read;
 
@@ -65,7 +63,7 @@ impl Settings {
         match File::open(file_name) {
             Ok(mut file) => {
                 let mut text = String::new();
-                file.read_to_string(&mut text);
+                file.read_to_string(&mut text).unwrap();
                 let loaded = serde_json::from_str(&text);
                 return if loaded.is_ok() {
                     Some(loaded.unwrap())
@@ -78,6 +76,9 @@ impl Settings {
     }
 
     pub fn get_origin(&self) -> Bytes {
+        if self.origin.eq("") {
+            return Bytes::zero32();
+        }
         let origin = crate::from_hex(&self.origin).expect("Wrong origin in settings");
         Bytes::from_bytes(origin.as_slice())
     }
diff --git a/src/keys.rs b/src/keys.rs
index 48fe3b2..9094079 100644
--- a/src/keys.rs
+++ b/src/keys.rs
@@ -7,7 +7,7 @@ use rand::{thread_rng, Rng};
 use std::fmt;
 use std::fs;
 use std::fs::File;
-use std::io::{Read, Write};
+use std::io::Write;
 use std::path::Path;
 use serde::export::fmt::Error;
 use serde::{Serialize, Deserialize, Serializer, Deserializer};
@@ -26,7 +26,7 @@ pub struct Keystore {
 
 impl Keystore {
     pub fn new() -> Self {
-        let mut buf = [0u8; 64];
+        let mut buf = [0u8; 32];
         let mut rng = thread_rng();
         rng.fill(&mut buf);
         let (private, public) = keypair(&buf);
@@ -50,11 +50,11 @@ impl Keystore {
     }
 
     //TODO Implement error conditions
-    pub fn save(&self, filename: &str, password: &str) {
+    pub fn save(&self, filename: &str, _password: &str) {
         match File::create(Path::new(filename)) {
             Ok(mut f) => {
                 //TODO implement key encryption
-                f.write_all(&self.seed);
+                f.write_all(&self.seed).expect("Error saving keystore");
             }
             Err(_) => { println!("Error saving key file!"); }
         }
@@ -69,10 +69,10 @@ impl Keystore {
     }
 
     pub fn sign(&self, message: &[u8]) -> [u8; 64] {
-        signature(message, &self.private_key.data)
+        signature(message, self.private_key.data.as_slice())
     }
 
-    pub fn check(&self, message: &[u8], public_key: &[u8], signature: &[u8]) -> bool {
+    pub fn check(message: &[u8], public_key: &[u8], signature: &[u8]) -> bool {
         verify(message, public_key, signature)
     }
 
@@ -117,7 +117,7 @@ impl Bytes {
 
     /// Returns a byte slice of the hash contents.
     pub fn as_bytes(&self) -> &[u8] {
-        &self.data
+        self.data.as_slice()
     }
 
     pub fn zero32() -> Self {
@@ -189,3 +189,12 @@ impl<'dd> Deserialize<'dd> for Bytes {
         deserializer.deserialize_str(BytesVisitor)
     }
 }
+
+#[test]
+pub fn test_signature() {
+    let keystore: Keystore = Keystore::new();
+    let data = b"{ identity: 178135D209C697625E3EC71DA5C760382E54936F824EE5083908DA66B14ECE18,\
+    confirmation: A4A0AFECD1A511825226F0D3437C6C6BDAE83554040AA7AEB49DEFEAB0AE9EA4 }";
+    let signature = keystore.sign(data);
+    assert!(Keystore::check(data, keystore.get_public().as_bytes(), &signature), "Wrong signature!")
+}
diff --git a/src/main.rs b/src/main.rs
index 51249b3..50fe737 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,16 +1,15 @@
 #![windows_subsystem = "windows"]
 extern crate web_view;
 
-use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::thread;
 
-use rand::{Rng, RngCore};
-use serde::{Deserialize, Serialize};
+use rand::RngCore;
+use serde::{Deserialize};
 use web_view::*;
 
-use alfis::{Block, Blockchain, Bytes, Context, Keystore, Settings, Transaction};
+use alfis::{Blockchain, Bytes, Context, Keystore, Settings, Transaction};
 use alfis::event::Event;
 use alfis::miner::Miner;
 use alfis::p2p::Network;
@@ -31,7 +30,7 @@ fn main() {
         None => { generate_key(KEYSTORE_DIFFICULTY, Arc::new(AtomicBool::new(true))).expect("Could not load or generate keypair") }
         Some(keystore) => { keystore }
     };
-    let blockchain: Blockchain = Blockchain::new(settings.origin.clone(), settings.version);
+    let blockchain: Blockchain = Blockchain::new(&settings);
     let context: Arc<Mutex<Context>> = Arc::new(Mutex::new(Context::new(settings, keystore, blockchain)));
 
     let mut miner_obj = Miner::new(context.clone());
@@ -39,7 +38,7 @@ fn main() {
     let miner: Arc<Mutex<Miner>> = Arc::new(Mutex::new(miner_obj));
 
     let mut network = Network::new(context.clone());
-    network.start();
+    network.start().expect("Error starting network component");
 
     create_genesis_if_needed(&context, &miner);
     run_interface(context.clone(), miner.clone());
@@ -76,8 +75,8 @@ fn run_interface(context: Arc<Mutex<Context>>, miner: Arc<Mutex<Miner>>) {
             println!("Command {}", arg);
             match serde_json::from_str(arg).unwrap() {
                 Loaded => {
-                    web_view.eval("showMiningIndicator(false);");
-                    let mut handle = web_view.handle();
+                    web_view.eval("showMiningIndicator(false);").expect("Error evaluating!");
+                    let handle = web_view.handle();
                     let mut c = context.lock().unwrap();
                     c.bus.register(move |_uuid, e| {
                         println!("Got event from bus {:?}", &e);
@@ -89,9 +88,9 @@ fn run_interface(context: Arc<Mutex<Context>>, miner: Arc<Mutex<Miner>>) {
                             _ => { false }
                         };
                         handle.dispatch(move |web_view| {
-                            web_view.eval(&format!("showMiningIndicator({});", visible));
+                            web_view.eval(&format!("showMiningIndicator({});", visible)).expect("Error evaluating!");
                             return WVResult::Ok(());
-                        });
+                        }).expect("Error dispatching!");
                         true
                     });
                 }
@@ -112,11 +111,11 @@ fn run_interface(context: Arc<Mutex<Context>>, miner: Arc<Mutex<Miner>>) {
                 CheckDomain { name} => {
                     let c = context.lock().unwrap();
                     let available = c.get_blockchain().is_domain_available(&name, &c.get_keystore());
-                    web_view.eval(&format!("domainAvailable({})", available));
+                    web_view.eval(&format!("domainAvailable({})", available)).expect("Error evaluating!");
                 }
                 CreateDomain { name, records, tags } => {
                     let keystore = {
-                        let mut guard = context.lock().unwrap();
+                        let guard = context.lock().unwrap();
                         guard.get_keystore()
                     };
                     create_domain(miner.clone(), name, records, &keystore);
@@ -152,7 +151,7 @@ fn create_domain<S: Into<String>>(miner: Arc<Mutex<Miner>>, name: S, data: S, ke
     println!("Generating domain {}", name);
     //let rec_vector: Vec<String> = records.into().trim().split("\n").map(|s| s.trim()).map(String::from).collect();
     //let tags_vector: Vec<String> = tags.into().trim().split(",").map(|s| s.trim()).map(String::from).collect();
-    let mut transaction = { create_transaction(keystore, name, "domain".into(), data.into()) };
+    let transaction = { create_transaction(keystore, name, "domain".into(), data.into()) };
     let mut miner_guard = miner.lock().unwrap();
     miner_guard.add_transaction(transaction);
 }
@@ -168,10 +167,10 @@ fn create_transaction<S: Into<String>>(keystore: &Keystore, name: S, method: S,
 }
 
 fn create_key(context: Arc<Mutex<Context>>, filename: &str, password: &str) {
-    let mut mining = Arc::new(AtomicBool::new(true));
+    let mining = Arc::new(AtomicBool::new(true));
+    { context.lock().unwrap().bus.post(Event::KeyGeneratorStarted); }
     for _ in 0..num_cpus::get() {
         let context = context.clone();
-        { context.lock().unwrap().bus.post(Event::KeyGeneratorStarted); }
         let filename= filename.to_owned();
         let password= password.to_owned();
         let mining = mining.clone();
@@ -201,7 +200,7 @@ fn create_key(context: Arc<Mutex<Context>>, filename: &str, password: &str) {
 
 fn generate_key(difficulty: usize, mining: Arc<AtomicBool>) -> Option<Keystore> {
     let mut rng = rand::thread_rng();
-    let mut buf = [0u8; 64];
+    let mut buf = [0u8; 32];
     loop {
         rng.fill_bytes(&mut buf);
         let keystore = Keystore::from_bytes(&buf);
@@ -213,7 +212,6 @@ fn generate_key(difficulty: usize, mining: Arc<AtomicBool>) -> Option<Keystore>
             return None;
         }
     }
-    None
 }
 
 #[derive(Deserialize)]
diff --git a/src/miner.rs b/src/miner.rs
index 2431431..8e378ed 100644
--- a/src/miner.rs
+++ b/src/miner.rs
@@ -8,15 +8,12 @@ use crypto::digest::Digest;
 use crypto::sha2::Sha256;
 use num_cpus;
 
-use crate::{Block, Bytes, Context, hash_is_good, Keystore, Transaction};
+use crate::{Block, Bytes, Context, hash_is_good, Transaction};
 use crate::event::Event;
 
 pub struct Miner {
     context: Arc<Mutex<Context>>,
-    keystore: Keystore,
-    version: u32,
     transactions: Arc<Mutex<Vec<Transaction>>>,
-    last_block: Option<Block>,
     running: Arc<AtomicBool>,
     mining: Arc<AtomicBool>,
     cond_var: Arc<Condvar>
@@ -24,13 +21,9 @@ pub struct Miner {
 
 impl Miner {
     pub fn new(context: Arc<Mutex<Context>>) -> Self {
-        let c = context.lock().unwrap();
         Miner {
             context: context.clone(),
-            keystore: c.keystore.clone(),
-            version: c.settings.version,
             transactions: Arc::new(Mutex::new(Vec::new())),
-            last_block: c.blockchain.blocks.last().cloned(),
             running: Arc::new(AtomicBool::new(false)),
             mining: Arc::new(AtomicBool::new(false)),
             cond_var: Arc::new(Condvar::new())
@@ -65,19 +58,17 @@ impl Miner {
 
                 let mut lock = transactions.lock().unwrap();
                 if lock.len() > 0 {
-                    println!("Starting to mine some transaction");
+                    println!("Got new transaction to mine");
                     let transaction = lock.remove(0);
                     mining.store(true, Ordering::Relaxed);
                     Miner::mine_internal(context.clone(), transactions.clone(), transaction, mining.clone(), cond_var.clone());
                 } else {
-                    println!("Waiting for transactions");
-                    cond_var.wait(lock);
-                    println!("Got notified on new transaction");
+                    let _ = cond_var.wait(lock).expect("Error in wait lock!");
                 }
             }
         });
         let mining = self.mining.clone();
-        self.context.lock().unwrap().bus.register(move |uuid, e| {
+        self.context.lock().unwrap().bus.register(move |_uuid, e| {
             if e == Event::ActionStopMining {
                 mining.store(false, Ordering::Relaxed);
             }
@@ -90,13 +81,11 @@ impl Miner {
     }
 
     fn mine_internal(context: Arc<Mutex<Context>>, transactions: Arc<Mutex<Vec<Transaction>>>, mut transaction: Transaction, mining: Arc<AtomicBool>, cond_var: Arc<Condvar>) {
-        let mut last_block_time = 0i64;
-        let mut version= 0u32;
-        {
+        let version= {
             let mut c = context.lock().unwrap();
             c.bus.post(Event::MinerStarted);
-            version = c.settings.version;
-        }
+            c.settings.version
+        };
         let block = {
             if transaction.signature.is_zero() {
                 // Signing it with private key from Keystore
@@ -114,7 +103,6 @@ impl Miner {
                     Block::new(0, Utc::now().timestamp(), version, Bytes::zero32(), Some(transaction.clone()))
                 },
                 Some(block) => {
-                    last_block_time = block.timestamp;
                     // Creating a block with that signed transaction
                     Block::new(block.index + 1, Utc::now().timestamp(), version, block.hash.clone(), Some(transaction.clone()))
                 },
@@ -134,11 +122,10 @@ impl Miner {
             let cond_var = cond_var.clone();
             thread::spawn(move || {
                 live_threads.fetch_add(1, Ordering::Relaxed);
-                let mut count = 0u32;
-                match find_hash(&mut Sha256::new(), block, last_block_time, mining.clone()) {
+                match find_hash(&mut Sha256::new(), block, mining.clone()) {
                     None => {
                         println!("Mining did not find suitable hash or was stopped");
-                        count = live_threads.fetch_sub(1, Ordering::Relaxed);
+                        let count = live_threads.fetch_sub(1, Ordering::Relaxed);
                         // If this is the last thread, but mining was not stopped by another thread
                         if count == 0 && mining.load(Ordering::Relaxed) {
                             // If all threads came empty with mining we return transaction to the queue
@@ -148,9 +135,8 @@ impl Miner {
                         }
                     },
                     Some(block) => {
-                        count = live_threads.fetch_sub(1, Ordering::Relaxed);
                         let mut context = context.lock().unwrap();
-                        context.blockchain.add_block(block);
+                        context.blockchain.add_block(block).expect("Error adding fresh mined block!");
                         context.bus.post(Event::MinerStopped);
                         mining.store(false, Ordering::Relaxed);
                     },
@@ -160,22 +146,16 @@ impl Miner {
     }
 }
 
-fn find_hash(digest: &mut dyn Digest, mut block: Block, prev_block_time: i64, running: Arc<AtomicBool>) -> Option<Block> {
+fn find_hash(digest: &mut dyn Digest, mut block: Block, running: Arc<AtomicBool>) -> Option<Block> {
     let mut buf: [u8; 32] = [0; 32];
     block.random = rand::random();
     println!("Mining block {}", serde_json::to_string(&block).unwrap());
-    //let start_difficulty = block.difficulty;
     for nonce in 0..std::u64::MAX {
         if !running.load(Ordering::Relaxed) {
             return None;
         }
         block.timestamp = Utc::now().timestamp();
         block.nonce = nonce;
-        // if nonce % 1000 == 0 {
-        //     println!("Nonce {}", nonce);
-        // }
-        // TODO uncomment for real run
-        //block.difficulty = start_difficulty + get_time_difficulty(prev_block_time, block.timestamp);
 
         digest.reset();
         digest.input(serde_json::to_string(&block).unwrap().as_bytes());
@@ -186,13 +166,4 @@ fn find_hash(digest: &mut dyn Digest, mut block: Block, prev_block_time: i64, ru
         }
     }
     None
-}
-
-fn get_time_difficulty(prev_time: i64, now: i64) -> usize {
-    let diff = now - prev_time;
-    if diff < 900_000 {
-        (900_000 as usize - diff as usize) / 60_000
-    } else {
-        0
-    }
 }
\ No newline at end of file
diff --git a/src/p2p/message.rs b/src/p2p/message.rs
index c5d841f..8309d72 100644
--- a/src/p2p/message.rs
+++ b/src/p2p/message.rs
@@ -2,7 +2,6 @@ extern crate serde;
 extern crate serde_json;
 
 use serde::{Deserialize, Serialize};
-use crate::p2p::peer::Peer;
 
 #[derive(Debug, Serialize, Deserialize)]
 pub enum Message {
diff --git a/src/p2p/network.rs b/src/p2p/network.rs
index 553b22d..34a331b 100644
--- a/src/p2p/network.rs
+++ b/src/p2p/network.rs
@@ -2,7 +2,6 @@ extern crate serde;
 extern crate serde_json;
 
 use std::{io, thread};
-use std::collections::HashMap;
 use std::io::{Read, Write};
 use std::sync::{Arc, Mutex};
 use std::time::Duration;
@@ -11,11 +10,9 @@ use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
 use mio::{Events, Interest, Poll, Registry, Token};
 use mio::event::Event;
 use mio::net::{TcpListener, TcpStream};
-use serde::{Deserialize, Serialize};
 
 use crate::{Context, Block, p2p::Message, p2p::State, p2p::Peer, p2p::Peers};
 use std::net::{SocketAddr, IpAddr, SocketAddrV4};
-use std::borrow::BorrowMut;
 
 const SERVER: Token = Token(0);
 const POLL_TIMEOUT: Option<Duration> = Some(Duration::from_millis(3000));
@@ -88,7 +85,7 @@ impl Network {
                         }
                         token => {
                             match peers.get_mut_peer(&token) {
-                                Some(peer) => {
+                                Some(_peer) => {
                                     match handle_connection_event(context.clone(), &mut peers, &poll.registry(), &event) {
                                         Ok(result) => {
                                             if !result {
@@ -123,7 +120,7 @@ fn handle_connection_event(context: Arc<Mutex<Context>>, peers: &mut Peers, regi
 
     if event.is_readable() {
         let data = {
-            let mut peer = peers.get_mut_peer(&event.token()).expect("Error getting peer for connection");
+            let peer = peers.get_mut_peer(&event.token()).expect("Error getting peer for connection");
             let mut stream = peer.get_stream();
             read_message(&mut stream)
         };
@@ -134,8 +131,8 @@ fn handle_connection_event(context: Arc<Mutex<Context>>, peers: &mut Peers, regi
                 Ok(message) => {
                     println!("Got message from socket {}: {:?}", &event.token().0, &message);
                     let new_state = handle_message(context.clone(), message, peers, &event.token());
-                    let mut peer = peers.get_mut_peer(&event.token()).unwrap();
-                    let mut stream = peer.get_stream();
+                    let peer = peers.get_mut_peer(&event.token()).unwrap();
+                    let stream = peer.get_stream();
                     match new_state {
                         State::Message { data } => {
                             if event.is_writable() {
@@ -154,7 +151,7 @@ fn handle_connection_event(context: Arc<Mutex<Context>>, peers: &mut Peers, regi
                         State::Error => {}
                         State::Banned => {}
                         State::Offline { .. } => {
-                            peer.set_state(State::offline(1));
+                            peer.set_state(State::offline());
                         }
                     }
                 }
@@ -175,7 +172,7 @@ fn handle_connection_event(context: Arc<Mutex<Context>>, peers: &mut Peers, regi
                     State::Connecting => {
                         println!("Sending hello to socket {}", event.token().0);
                         let data: String = {
-                            let mut c = context.lock().unwrap();
+                            let c = context.lock().unwrap();
                             let message = Message::hand(&c.settings.origin, c.settings.version, c.settings.public);
                             serde_json::to_string(&message).unwrap()
                         };
@@ -191,7 +188,7 @@ fn handle_connection_event(context: Arc<Mutex<Context>>, peers: &mut Peers, regi
                         println!("Odd version of pings :)");
                         if from.elapsed().as_secs() >= 30 {
                             let data: String = {
-                                let mut c = context.lock().unwrap();
+                                let c = context.lock().unwrap();
                                 let message = Message::ping(c.blockchain.height());
                                 serde_json::to_string(&message).unwrap()
                             };
@@ -232,7 +229,7 @@ fn read_message(stream: &mut &mut TcpStream) -> Result<Vec<u8>, Vec<u8>> {
             Err(ref err) if would_block(err) => break,
             Err(ref err) if interrupted(err) => continue,
             // Other errors we'll consider fatal.
-            Err(err) => return Err(buf),
+            Err(_) => return Err(buf),
         }
     }
     if buf.len() == data_size {
@@ -244,29 +241,30 @@ fn read_message(stream: &mut &mut TcpStream) -> Result<Vec<u8>, Vec<u8>> {
 
 fn send_message(connection: &mut TcpStream, data: &Vec<u8>) {
     // TODO handle errors
-    connection.write_u32::<BigEndian>(data.len() as u32);
+    connection.write_u32::<BigEndian>(data.len() as u32).expect("Error sending message");
     connection.write_all(&data).expect("Error writing to socket");
-    connection.flush();
+    connection.flush().expect("Error sending message");
 }
 
 fn handle_message(context: Arc<Mutex<Context>>, message: Message, peers: &mut Peers, token: &Token) -> State {
-    let my_height = {
+    let (my_height, my_origin, my_version) = {
         let context = context.lock().unwrap();
-        context.blockchain.height()
+        (context.blockchain.height(), &context.settings.origin.clone(), context.settings.version)
     };
     match message {
-        Message::Hand { origin: origin, version, public } => {
-            let context = context.lock().unwrap();
-            if origin == context.settings.origin && version == context.settings.version {
-                let mut peer = peers.get_mut_peer(token).unwrap();
+        Message::Hand { origin, version, public } => {
+            if origin.eq(my_origin) && version == my_version {
+                let peer = peers.get_mut_peer(token).unwrap();
                 peer.set_public(public);
-                State::message(Message::shake(&context.settings.origin, context.settings.version, true, context.blockchain.height()))
+                State::message(Message::shake(&origin, version, true, my_height))
             } else {
                 State::Error
             }
         }
         Message::Shake { origin, version, ok, height } => {
-            // TODO check origin and version for compatibility
+            if origin.ne(my_origin) || version != my_version {
+                return State::Error;
+            }
             if ok {
                 if height > my_height {
                     State::message(Message::GetBlock { index: my_height + 1u64 })
@@ -308,6 +306,7 @@ fn handle_message(context: Arc<Mutex<Context>>, message: Message, peers: &mut Pe
             }
         }
         Message::Block { index, block } => {
+            println!("Received block {}", index);
             let block: Block = match serde_json::from_str(&block) {
                 Ok(block) => block,
                 Err(_) => return State::Error
@@ -316,8 +315,10 @@ fn handle_message(context: Arc<Mutex<Context>>, message: Message, peers: &mut Pe
             let context = context.clone();
             thread::spawn(move || {
                 let mut context = context.lock().unwrap();
-                context.blockchain.add_block(block);
-                context.bus.post(crate::event::Event::BlockchainChanged)
+                match context.blockchain.add_block(block) {
+                    Ok(_) => { context.bus.post(crate::event::Event::BlockchainChanged); }
+                    Err(_) => { println!("Error adding received block"); }
+                }
             });
             State::idle()
         }
diff --git a/src/p2p/peer.rs b/src/p2p/peer.rs
index 7bb1cb5..6f6c4c9 100644
--- a/src/p2p/peer.rs
+++ b/src/p2p/peer.rs
@@ -1,7 +1,6 @@
 use crate::p2p::State;
 use std::net::SocketAddr;
 use mio::net::TcpStream;
-use std::sync::RwLock;
 
 #[derive(Debug)]
 pub struct Peer {
@@ -49,9 +48,9 @@ impl Peer {
         self.state.disabled()
     }
 
+    /// If loopback address then we care about ip and port.
+    /// If regular address then we only care about the ip and ignore the port.
     pub fn equals(&self, addr: &SocketAddr) -> bool {
-        /// If loopback address then we care about ip and port.
-        /// If regular address then we only care about the ip and ignore the port.
         if self.addr.ip().is_loopback() {
             self.addr == *addr
         } else {
diff --git a/src/p2p/peers.rs b/src/p2p/peers.rs
index d31b39b..c079b97 100644
--- a/src/p2p/peers.rs
+++ b/src/p2p/peers.rs
@@ -80,7 +80,7 @@ impl Peers {
     }
 
     pub fn send_pings(&mut self, registry: &Registry, height: u64) {
-        for (token, mut peer) in self.peers.iter_mut() {
+        for (token, peer) in self.peers.iter_mut() {
             match peer.get_state() {
                 State::Idle { from } => {
                     if from.elapsed().as_secs() >= PING_PERIOD {
@@ -93,7 +93,7 @@ impl Peers {
                         };
 
                         peer.set_state(State::message(message));
-                        let mut stream = peer.get_stream();
+                        let stream = peer.get_stream();
                         registry.reregister(stream, token.clone(), Interest::WRITABLE).unwrap();
                     }
                 }
diff --git a/src/p2p/state.rs b/src/p2p/state.rs
index a171180..ef169f7 100644
--- a/src/p2p/state.rs
+++ b/src/p2p/state.rs
@@ -9,7 +9,7 @@ pub enum State {
     Message { data: Vec<u8> },
     Error,
     Banned,
-    Offline { from: Instant, attempts: usize },
+    Offline { from: Instant },
 }
 
 impl State {
@@ -17,19 +17,8 @@ impl State {
         Self::Idle { from: Instant::now() }
     }
 
-    pub fn offline(attempts: usize) -> Self {
-        Self::Offline { attempts, from: Instant::now() }
-    }
-
-    pub fn still_offline(state: Self) -> Self {
-        match state {
-            State::Offline { attempts, from } => {
-                Self::Offline { attempts: attempts + 1, from }
-            }
-            _ => {
-                Self::Offline { attempts: 1, from: Instant::now() }
-            }
-        }
+    pub fn offline() -> Self {
+        Self::Offline { from: Instant::now() }
     }
 
     pub fn message(message: Message) -> Self {
@@ -51,7 +40,7 @@ impl State {
         match self {
             State::Error => { true }
             State::Banned => { true }
-            State::Offline { from, attempts } => {
+            State::Offline { from} => {
                 from.elapsed().as_secs() < 60 // We check offline peers to become online every 5 minutes
             }
             _ => { false }
diff --git a/src/simplebus.rs b/src/simplebus.rs
index 063b9be..c0ed4dd 100644
--- a/src/simplebus.rs
+++ b/src/simplebus.rs
@@ -1,4 +1,3 @@
-use crate::event::Event;
 use uuid::Uuid;
 use std::collections::HashMap;
 
@@ -11,7 +10,7 @@ impl<T: Clone> Bus<T> {
         Bus { listeners: HashMap::new() }
     }
 
-    pub fn register<F>(&mut self, mut closure: F) -> Uuid where F: FnMut(&Uuid, T) -> bool + Send + Sync + 'static {
+    pub fn register<F>(&mut self, closure: F) -> Uuid where F: FnMut(&Uuid, T) -> bool + Send + Sync + 'static {
         let uuid = Uuid::new_v4();
         self.listeners.insert(uuid.clone(), Box::new(closure));
         uuid
@@ -30,7 +29,6 @@ impl<T: Clone> Bus<T> {
 
 mod tests {
     use std::sync::{Arc, Mutex};
-    use std::sync::atomic::{AtomicI32, Ordering};
     use std::thread;
     use std::time::Duration;
 
@@ -39,8 +37,8 @@ mod tests {
 
     #[test]
     fn test1() {
-        let mut string = Arc::new(Mutex::new(String::from("start")));
-        let mut bus = Arc::new(Mutex::new(Bus::new()));
+        let string = Arc::new(Mutex::new(String::from("start")));
+        let bus = Arc::new(Mutex::new(Bus::new()));
         let string_copy = string.clone();
         {
             bus.lock().unwrap().register(move |_uuid, e| {
@@ -56,7 +54,7 @@ mod tests {
             bus2.lock().unwrap().post(Event::BlockchainChanged);
         });
 
-        let mut guard = string.lock().unwrap();
+        let guard = string.lock().unwrap();
         thread::sleep(Duration::from_millis(100));
         println!("string = {}", &guard);
     }