diff --git a/Cargo.toml b/Cargo.toml
index cc0953f8f..19c64113c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,5 +13,5 @@ rustc-serialize = "0.3"
 arrayvec = "0.3"
 mio = "0.*"
 rand = "0.*"
-tiny-keccak = "0.2"
+tiny-keccak = "0.3"
 rocksdb = "0.2.1"
diff --git a/src/bytes.rs b/src/bytes.rs
index 1b331cf15..73592643d 100644
--- a/src/bytes.rs
+++ b/src/bytes.rs
@@ -10,74 +10,91 @@ use std::fmt;
 use std::error::Error as StdError;
 use uint::{U128, U256};
 
+pub trait BytesConvertable {
+	fn bytes(&self) -> &[u8];
+}
+
+impl<'a> BytesConvertable for &'a [u8] {
+	fn bytes(&self) -> &[u8] { self }
+}
+
+impl BytesConvertable for Vec<u8> {
+	fn bytes(&self) -> &[u8] { self }
+}
+
+#[test]
+fn bytes_convertable() {
+	assert_eq!(vec![0x12u8, 0x34].bytes(), &[0x12u8, 0x34]);
+}
+
 /// TODO: optimise some conversations
 pub trait ToBytes {
-    fn to_bytes(&self) -> Vec<u8>;
-    fn to_bytes_len(&self) -> usize { self.to_bytes().len() }
-    fn first_byte(&self) -> Option<u8> { self.to_bytes().first().map(|&x| { x })}
+	fn to_bytes(&self) -> Vec<u8>;
+	fn to_bytes_len(&self) -> usize { self.to_bytes().len() }
+	fn first_byte(&self) -> Option<u8> { self.to_bytes().first().map(|&x| { x })}
 }
 
 impl <'a> ToBytes for &'a str {
-    fn to_bytes(&self) -> Vec<u8> {
-        From::from(*self)
-    }
-    
-    fn to_bytes_len(&self) -> usize { self.len() }
+	fn to_bytes(&self) -> Vec<u8> {
+		From::from(*self)
+	}
+	
+	fn to_bytes_len(&self) -> usize { self.len() }
 }
 
 impl ToBytes for String {
-    fn to_bytes(&self) -> Vec<u8> {
-        let s: &str = self.as_ref();
-        From::from(s)
-    }
-    
-    fn to_bytes_len(&self) -> usize { self.len() }
+	fn to_bytes(&self) -> Vec<u8> {
+		let s: &str = self.as_ref();
+		From::from(s)
+	}
+	
+	fn to_bytes_len(&self) -> usize { self.len() }
 }
 
 impl ToBytes for u8 {
-    fn to_bytes(&self) -> Vec<u8> {
-        match *self {
-            0 => vec![],
-            _ => vec![*self]
-        }
-    }
+	fn to_bytes(&self) -> Vec<u8> {
+		match *self {
+			0 => vec![],
+			_ => vec![*self]
+		}
+	}
 
-    fn to_bytes_len(&self) -> usize {
-        match *self {
-            0 => 0,
-            _ => 1
-        }
-    }
-    fn first_byte(&self) -> Option<u8> { 
-        match *self {
-            0 => None,
-            _ => Some(*self) 
-        }
-    }
+	fn to_bytes_len(&self) -> usize {
+		match *self {
+			0 => 0,
+			_ => 1
+		}
+	}
+	fn first_byte(&self) -> Option<u8> { 
+		match *self {
+			0 => None,
+			_ => Some(*self) 
+		}
+	}
 }
 
 impl ToBytes for u64 {
-    fn to_bytes(&self) -> Vec<u8> {
-        let mut res= vec![];
-        let count = self.to_bytes_len();
-        res.reserve(count);
-        for i in 0..count {
-            let j = count - 1 - i;
-            res.push((*self >> (j * 8)) as u8);
-        }
-        res
-    }
+	fn to_bytes(&self) -> Vec<u8> {
+		let mut res= vec![];
+		let count = self.to_bytes_len();
+		res.reserve(count);
+		for i in 0..count {
+			let j = count - 1 - i;
+			res.push((*self >> (j * 8)) as u8);
+		}
+		res
+	}
 
-    fn to_bytes_len(&self) -> usize { 8 - self.leading_zeros() as usize / 8 }
+	fn to_bytes_len(&self) -> usize { 8 - self.leading_zeros() as usize / 8 }
 }
 
 macro_rules! impl_map_to_bytes {
-    ($from: ident, $to: ty) => {
-        impl ToBytes for $from {
-            fn to_bytes(&self) -> Vec<u8> { (*self as $to).to_bytes() }
-            fn to_bytes_len(&self) -> usize { (*self as $to).to_bytes_len() }
-        }
-    }
+	($from: ident, $to: ty) => {
+		impl ToBytes for $from {
+			fn to_bytes(&self) -> Vec<u8> { (*self as $to).to_bytes() }
+			fn to_bytes_len(&self) -> usize { (*self as $to).to_bytes_len() }
+		}
+	}
 }
 
 impl_map_to_bytes!(usize, u64);
@@ -85,21 +102,21 @@ impl_map_to_bytes!(u16, u64);
 impl_map_to_bytes!(u32, u64);
 
 macro_rules! impl_uint_to_bytes {
-    ($name: ident) => {
-        impl ToBytes for $name {
-            fn to_bytes(&self) -> Vec<u8> { 
-                let mut res= vec![];
-                let count = self.to_bytes_len();
-                res.reserve(count);
-                for i in 0..count {
-                    let j = count - 1 - i;
-                    res.push(self.byte(j));
-                }
-                res
-            }
-            fn to_bytes_len(&self) -> usize { (self.bits() + 7) / 8 }
-        }
-    }
+	($name: ident) => {
+		impl ToBytes for $name {
+			fn to_bytes(&self) -> Vec<u8> { 
+				let mut res= vec![];
+				let count = self.to_bytes_len();
+				res.reserve(count);
+				for i in 0..count {
+					let j = count - 1 - i;
+					res.push(self.byte(j));
+				}
+				res
+			}
+			fn to_bytes_len(&self) -> usize { (self.bits() + 7) / 8 }
+		}
+	}
 }
 
 impl_uint_to_bytes!(U256);
@@ -107,17 +124,17 @@ impl_uint_to_bytes!(U128);
 
 #[derive(Debug, PartialEq, Eq)]
 pub enum FromBytesError {
-    UnexpectedEnd
+	UnexpectedEnd
 }
 
 impl StdError for FromBytesError {
-    fn description(&self) -> &str { "from_bytes error" }
+	fn description(&self) -> &str { "from_bytes error" }
 }
 
 impl fmt::Display for FromBytesError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(&self, f)
-    }
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		fmt::Debug::fmt(&self, f)
+	}
 }
 
 pub type FromBytesResult<T> = Result<T, FromBytesError>;
@@ -126,48 +143,48 @@ pub type FromBytesResult<T> = Result<T, FromBytesError>;
 /// of the return type
 /// TODO: check size of bytes before conversation and return appropriate error
 pub trait FromBytes: Sized {
-    fn from_bytes(bytes: &[u8]) -> FromBytesResult<Self>;
+	fn from_bytes(bytes: &[u8]) -> FromBytesResult<Self>;
 }
 
 impl FromBytes for String {
-    fn from_bytes(bytes: &[u8]) -> FromBytesResult<String> {
-        Ok(::std::str::from_utf8(bytes).unwrap().to_string())
-    }
+	fn from_bytes(bytes: &[u8]) -> FromBytesResult<String> {
+		Ok(::std::str::from_utf8(bytes).unwrap().to_string())
+	}
 }
 
 impl FromBytes for u8 {
-    fn from_bytes(bytes: &[u8]) -> FromBytesResult<u8> {
-        match bytes.len() {
-            0 => Ok(0),
-            _ => Ok(bytes[0])
-        }
-    }
+	fn from_bytes(bytes: &[u8]) -> FromBytesResult<u8> {
+		match bytes.len() {
+			0 => Ok(0),
+			_ => Ok(bytes[0])
+		}
+	}
 }
 
 impl FromBytes for u64 {
-    fn from_bytes(bytes: &[u8]) -> FromBytesResult<u64> {
-        match bytes.len() {
-            0 => Ok(0),
-            l => {
-                let mut res = 0u64;
-                for i in 0..l {
-                    let shift = (l - 1 - i) * 8;
-                    res = res + ((bytes[i] as u64) << shift);
-                }
-                Ok(res)
-            }
-        }
-    }
+	fn from_bytes(bytes: &[u8]) -> FromBytesResult<u64> {
+		match bytes.len() {
+			0 => Ok(0),
+			l => {
+				let mut res = 0u64;
+				for i in 0..l {
+					let shift = (l - 1 - i) * 8;
+					res = res + ((bytes[i] as u64) << shift);
+				}
+				Ok(res)
+			}
+		}
+	}
 }
 
 macro_rules! impl_map_from_bytes {
-    ($from: ident, $to: ident) => {
-        impl FromBytes for $from {
-            fn from_bytes(bytes: &[u8]) -> FromBytesResult<$from> {
-                $to::from_bytes(bytes).map(| x | { x as $from })
-            }
-        }
-    }
+	($from: ident, $to: ident) => {
+		impl FromBytes for $from {
+			fn from_bytes(bytes: &[u8]) -> FromBytesResult<$from> {
+				$to::from_bytes(bytes).map(| x | { x as $from })
+			}
+		}
+	}
 }
 
 impl_map_from_bytes!(usize, u64);
@@ -175,13 +192,13 @@ impl_map_from_bytes!(u16, u64);
 impl_map_from_bytes!(u32, u64);
 
 macro_rules! impl_uint_from_bytes {
-    ($name: ident) => {
-        impl FromBytes for $name {
-            fn from_bytes(bytes: &[u8]) -> FromBytesResult<$name> {
-                Ok($name::from(bytes))
-            }
-        }
-    }
+	($name: ident) => {
+		impl FromBytes for $name {
+			fn from_bytes(bytes: &[u8]) -> FromBytesResult<$name> {
+				Ok($name::from(bytes))
+			}
+		}
+	}
 }
 
 impl_uint_from_bytes!(U256);
diff --git a/src/hash.rs b/src/hash.rs
index 17f1c6c71..044153e0c 100644
--- a/src/hash.rs
+++ b/src/hash.rs
@@ -6,6 +6,7 @@ use rustc_serialize::hex::*;
 use error::EthcoreError;
 use rand::Rng;
 use rand::os::OsRng;
+use bytes::BytesConvertable;
 
 macro_rules! impl_hash {
 	($from: ident, $size: expr) => {
@@ -25,6 +26,16 @@ macro_rules! impl_hash {
 				let mut rng = OsRng::new().unwrap();
 				rng.fill_bytes(&mut self.0);
 			}
+
+			pub fn mut_bytes(&mut self) -> &mut [u8; $size] {
+				&mut self.0
+			}
+		}
+
+		impl BytesConvertable for $from {
+			fn bytes(&self) -> &[u8] {
+				&self.0
+			}
 		}
 
 		impl FromStr for $from {
diff --git a/src/lib.rs b/src/lib.rs
index 5b6676169..7c480c02b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -15,6 +15,7 @@ pub mod bytes;
 pub mod rlp;
 pub mod vector;
 pub mod db;
+pub mod sha3;
 
 //pub mod network;
 
diff --git a/src/sha3.rs b/src/sha3.rs
new file mode 100644
index 000000000..61c5c26f8
--- /dev/null
+++ b/src/sha3.rs
@@ -0,0 +1,29 @@
+use std::mem::uninitialized;
+use tiny_keccak::keccak_256;
+use bytes::BytesConvertable;
+use hash::H256;
+
+trait Hashable {
+	fn sha3(&self) -> H256;
+}
+
+impl<T> Hashable for T where T: BytesConvertable {
+	fn sha3(&self) -> H256 {
+		unsafe {
+			let mut ret: H256 = uninitialized();
+			keccak_256(self.bytes(), ret.mut_bytes());
+			ret
+		}
+	}
+}
+
+#[test]
+fn sha3_empty() {
+	use std::str::FromStr;
+	assert_eq!((&[0u8; 0][..]).sha3(), H256::from_str("c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470").unwrap());
+}
+#[test]
+fn sha3_as() {
+	use std::str::FromStr;
+	assert_eq!((&[0x41u8; 32][..]).sha3(), H256::from_str("59cad5948673622c1d64e2322488bf01619f7ff45789741b15a9f782ce9290a8").unwrap());
+}