diff --git a/src/bloom.rs b/src/bloom.rs
new file mode 100644
index 000000000..fe619fae6
--- /dev/null
+++ b/src/bloom.rs
@@ -0,0 +1,7 @@
+use bytes::BytesConvertable;
+// use hash::FixedHash;
+
+pub trait Bloomable {
+	fn shift_bloom<T>(&mut self, bytes: &T) where T: BytesConvertable;
+	fn contains_bloom<T>(&self, bytes: &T) -> bool where T: BytesConvertable;
+}
diff --git a/src/hash.rs b/src/hash.rs
index 044153e0c..fc89b4ab9 100644
--- a/src/hash.rs
+++ b/src/hash.rs
@@ -8,27 +8,22 @@ use rand::Rng;
 use rand::os::OsRng;
 use bytes::BytesConvertable;
 
+/// types implementing FixedHash must be also BytesConvertable
+pub trait FixedHash: BytesConvertable {
+	fn random() -> Self;
+	fn randomize(&mut self);
+	fn mut_bytes(&mut self) -> &mut [u8];
+}
+
 macro_rules! impl_hash {
 	($from: ident, $size: expr) => {
 		#[derive(Eq)]
 		pub struct $from (pub [u8; $size]);
 
-		impl $from {
-			pub fn new() -> $from {
-				$from([0; $size])
-			}
-			pub fn random() -> $from {
-				let mut hash = $from::new();
-				hash.randomize();
-				hash
-			}
-			pub fn randomize(&mut self) {
-				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 $from {
+			fn new() -> $from {
+				$from([0; $size])
 			}
 		}
 
@@ -38,6 +33,23 @@ macro_rules! impl_hash {
 			}
 		}
 
+		impl FixedHash for $from {
+			fn random() -> $from {
+				let mut hash = $from::new();
+				hash.randomize();
+				hash
+			}
+
+			fn randomize(&mut self) {
+				let mut rng = OsRng::new().unwrap();
+				rng.fill_bytes(&mut self.0);
+			}
+
+			fn mut_bytes(&mut self) -> &mut [u8] {
+				&mut self.0
+			}
+		}
+
 		impl FromStr for $from {
 			type Err = EthcoreError;
 
diff --git a/src/lib.rs b/src/lib.rs
index 7c480c02b..a52e35925 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,6 +16,7 @@ pub mod rlp;
 pub mod vector;
 pub mod db;
 pub mod sha3;
+pub mod bloom;
 
 //pub mod network;
 
diff --git a/src/sha3.rs b/src/sha3.rs
index e2866d288..b7eec2a5f 100644
--- a/src/sha3.rs
+++ b/src/sha3.rs
@@ -1,7 +1,7 @@
 use std::mem::uninitialized;
 use tiny_keccak::keccak_256;
 use bytes::BytesConvertable;
-use hash::H256;
+use hash::{FixedHash, H256};
 
 trait Hashable {
 	fn sha3(&self) -> H256;