diff --git a/common/types.go b/common/types.go
index e0963a7c5d..1fe31657b9 100644
--- a/common/types.go
+++ b/common/types.go
@@ -27,27 +27,27 @@ func StringToAddress(s string) Address { return BytesToAddress([]byte(s)) }
 // Don't use the default 'String' method in case we want to overwrite
 
 // Get the string representation of the underlying hash
-func (h Hash) Str() string {
+func (h *Hash) Str() string {
 	return string(h[:])
 }
 
 // Sets the hash to the value of b. If b is larger than len(h) it will panic
-func (h Hash) SetBytes(b []byte) {
+func (h *Hash) SetBytes(b []byte) {
 	if len(b) > len(h) {
 		panic("unable to set bytes. too big")
 	}
 
 	// reverse loop
-	for i := len(b); i >= 0; i-- {
+	for i := len(b) - 1; i >= 0; i-- {
 		h[i] = b[i]
 	}
 }
 
 // Set string `s` to h. If s is larger than len(h) it will panic
-func (h Hash) SetString(s string) { h.SetBytes([]byte(s)) }
+func (h *Hash) SetString(s string) { h.SetBytes([]byte(s)) }
 
 // Sets h to other
-func (h Hash) Set(other Hash) {
+func (h *Hash) Set(other Hash) {
 	for i, v := range other {
 		h[i] = v
 	}
diff --git a/trie/iterator.go b/trie/iterator.go
index fda7c6cbe9..aff614f953 100644
--- a/trie/iterator.go
+++ b/trie/iterator.go
@@ -2,17 +2,19 @@ package trie
 
 import (
 	"bytes"
+
+	"github.com/ethereum/go-ethereum/common"
 )
 
 type Iterator struct {
 	trie *Trie
 
-	Key   []byte
+	Key   common.Hash
 	Value []byte
 }
 
 func NewIterator(trie *Trie) *Iterator {
-	return &Iterator{trie: trie, Key: nil}
+	return &Iterator{trie: trie}
 }
 
 func (self *Iterator) Next() bool {
@@ -20,15 +22,15 @@ func (self *Iterator) Next() bool {
 	defer self.trie.mu.Unlock()
 
 	isIterStart := false
-	if self.Key == nil {
+	if (self.Key == common.Hash{}) {
 		isIterStart = true
-		self.Key = make([]byte, 32)
+		//self.Key = make([]byte, 32)
 	}
 
-	key := RemTerm(CompactHexDecode(string(self.Key)))
+	key := RemTerm(CompactHexDecode(self.Key.Str()))
 	k := self.next(self.trie.root, key, isIterStart)
 
-	self.Key = []byte(DecodeCompact(k))
+	self.Key = common.StringToHash(DecodeCompact(k))
 
 	return len(k) > 0
 }
diff --git a/trie/iterator_test.go b/trie/iterator_test.go
index 74d9e903cd..5f95caa683 100644
--- a/trie/iterator_test.go
+++ b/trie/iterator_test.go
@@ -22,7 +22,7 @@ func TestIterator(t *testing.T) {
 
 	it := trie.Iterator()
 	for it.Next() {
-		v[string(it.Key)] = true
+		v[it.Key.Str()] = true
 	}
 
 	for k, found := range v {
diff --git a/trie/secure_trie.go b/trie/secure_trie.go
index b9fa376b81..b31791cadb 100644
--- a/trie/secure_trie.go
+++ b/trie/secure_trie.go
@@ -1,34 +1,38 @@
 package trie
 
-import "github.com/ethereum/go-ethereum/crypto"
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+)
 
 type SecureTrie struct {
 	*Trie
 }
 
-func NewSecure(root []byte, backend Backend) *SecureTrie {
+func NewSecure(root common.Hash, backend Backend) *SecureTrie {
 	return &SecureTrie{New(root, backend)}
 }
 
-func (self *SecureTrie) Update(key, value []byte) Node {
-	return self.Trie.Update(crypto.Sha3(key), value)
-}
-func (self *SecureTrie) UpdateString(key, value string) Node {
-	return self.Update([]byte(key), []byte(value))
+func (self *SecureTrie) Update(key common.Hash, value []byte) Node {
+	return self.Trie.Update(common.BytesToHash(crypto.Sha3(key[:])), value)
 }
 
-func (self *SecureTrie) Get(key []byte) []byte {
-	return self.Trie.Get(crypto.Sha3(key))
+func (self *SecureTrie) UpdateString(key, value string) Node {
+	return self.Update(common.StringToHash(key), []byte(value))
+}
+
+func (self *SecureTrie) Get(key common.Hash) []byte {
+	return self.Trie.Get(common.BytesToHash(crypto.Sha3(key[:])))
 }
 func (self *SecureTrie) GetString(key string) []byte {
-	return self.Get([]byte(key))
+	return self.Get(common.StringToHash(key))
 }
 
-func (self *SecureTrie) Delete(key []byte) Node {
-	return self.Trie.Delete(crypto.Sha3(key))
+func (self *SecureTrie) Delete(key common.Hash) Node {
+	return self.Trie.Delete(common.BytesToHash(crypto.Sha3(key[:])))
 }
 func (self *SecureTrie) DeleteString(key string) Node {
-	return self.Delete([]byte(key))
+	return self.Delete(common.StringToHash(key))
 }
 
 func (self *SecureTrie) Copy() *SecureTrie {
diff --git a/trie/trie.go b/trie/trie.go
index cb1e5618f2..759718400c 100644
--- a/trie/trie.go
+++ b/trie/trie.go
@@ -11,14 +11,15 @@ import (
 )
 
 func ParanoiaCheck(t1 *Trie, backend Backend) (bool, *Trie) {
-	t2 := New(nil, backend)
+	t2 := New(common.Hash{}, backend)
 
 	it := t1.Iterator()
 	for it.Next() {
 		t2.Update(it.Key, it.Value)
 	}
 
-	return bytes.Equal(t2.Hash(), t1.Hash()), t2
+	a, b := t2.Hash(), t1.Hash()
+	return bytes.Equal(a[:], b[:]), t2
 }
 
 type Trie struct {
@@ -38,8 +39,8 @@ func New(root common.Hash, backend Backend) *Trie {
 		trie.cache = NewCache(backend)
 	}
 
-	if root != nil {
-		value := common.NewValueFromBytes(trie.cache.Get(root))
+	if (root != common.Hash{}) {
+		value := common.NewValueFromBytes(trie.cache.Get(root[:]))
 		trie.root = trie.mknode(value)
 	}
 
@@ -51,12 +52,13 @@ func (self *Trie) Iterator() *Iterator {
 }
 
 func (self *Trie) Copy() *Trie {
+	//cpy := make([]byte, 32)
+	//copy(cpy, self.roothash)
+
 	// cheap copying method
 	var cpy common.Hash
-	cpy.Set(self.roothash[:])
-	cpy := make([]byte, 32)
-	copy(cpy, self.roothash)
-	trie := New(nil, nil)
+	cpy.Set(self.roothash)
+	trie := New(common.Hash{}, nil)
 	trie.cache = self.cache.Copy()
 	if self.root != nil {
 		trie.root = self.root.Copy(trie)
@@ -66,21 +68,21 @@ func (self *Trie) Copy() *Trie {
 }
 
 // Legacy support
-func (self *Trie) Root() []byte { return self.Hash() }
-func (self *Trie) Hash() []byte {
-	var hash []byte
+func (self *Trie) Root() common.Hash { return self.Hash() }
+func (self *Trie) Hash() common.Hash {
+	var hash common.Hash
 	if self.root != nil {
 		t := self.root.Hash()
-		if byts, ok := t.([]byte); ok && len(byts) > 0 {
-			hash = byts
+		if h, ok := t.(common.Hash); ok && (h != common.Hash{}) {
+			hash = h
 		} else {
-			hash = crypto.Sha3(common.Encode(self.root.RlpData()))
+			hash = common.BytesToHash(crypto.Sha3(common.Encode(self.root.RlpData())))
 		}
 	} else {
-		hash = crypto.Sha3(common.Encode(""))
+		hash = common.BytesToHash(crypto.Sha3(common.Encode("")))
 	}
 
-	if !bytes.Equal(hash, self.roothash) {
+	if hash != self.roothash {
 		self.revisions.PushBack(self.roothash)
 		self.roothash = hash
 	}
@@ -105,19 +107,21 @@ func (self *Trie) Reset() {
 	self.cache.Reset()
 
 	if self.revisions.Len() > 0 {
-		revision := self.revisions.Remove(self.revisions.Back()).([]byte)
+		revision := self.revisions.Remove(self.revisions.Back()).(common.Hash)
 		self.roothash = revision
 	}
-	value := common.NewValueFromBytes(self.cache.Get(self.roothash))
+	value := common.NewValueFromBytes(self.cache.Get(self.roothash[:]))
 	self.root = self.mknode(value)
 }
 
-func (self *Trie) UpdateString(key, value string) Node { return self.Update([]byte(key), []byte(value)) }
-func (self *Trie) Update(key, value []byte) Node {
+func (self *Trie) UpdateString(key, value string) Node {
+	return self.Update(common.StringToHash(key), []byte(value))
+}
+func (self *Trie) Update(key common.Hash, value []byte) Node {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key.Str())
 
 	if len(value) != 0 {
 		self.root = self.insert(self.root, k, &ValueNode{self, value})
@@ -128,12 +132,12 @@ func (self *Trie) Update(key, value []byte) Node {
 	return self.root
 }
 
-func (self *Trie) GetString(key string) []byte { return self.Get([]byte(key)) }
-func (self *Trie) Get(key []byte) []byte {
+func (self *Trie) GetString(key string) []byte { return self.Get(common.StringToHash(key)) }
+func (self *Trie) Get(key common.Hash) []byte {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key.Str())
 
 	n := self.get(self.root, k)
 	if n != nil {
@@ -143,12 +147,12 @@ func (self *Trie) Get(key []byte) []byte {
 	return nil
 }
 
-func (self *Trie) DeleteString(key string) Node { return self.Delete([]byte(key)) }
-func (self *Trie) Delete(key []byte) Node {
+func (self *Trie) DeleteString(key string) Node { return self.Delete(common.StringToHash(key)) }
+func (self *Trie) Delete(key common.Hash) Node {
 	self.mu.Lock()
 	defer self.mu.Unlock()
 
-	k := CompactHexDecode(string(key))
+	k := CompactHexDecode(key.Str())
 	self.root = self.delete(self.root, k)
 
 	return self.root
diff --git a/trie/trie_test.go b/trie/trie_test.go
index 1393e0c97c..f5d17c3dae 100644
--- a/trie/trie_test.go
+++ b/trie/trie_test.go
@@ -5,8 +5,8 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 )
 
 type Db map[string][]byte
@@ -16,18 +16,18 @@ func (self Db) Put(k, v []byte)              { self[string(k)] = v }
 
 // Used for testing
 func NewEmpty() *Trie {
-	return New(nil, make(Db))
+	return New(common.Hash{}, make(Db))
 }
 
 func NewEmptySecure() *SecureTrie {
-	return NewSecure(nil, make(Db))
+	return NewSecure(common.Hash{}, make(Db))
 }
 
 func TestEmptyTrie(t *testing.T) {
 	trie := NewEmpty()
 	res := trie.Hash()
 	exp := crypto.Sha3(common.Encode(""))
-	if !bytes.Equal(res, exp) {
+	if !bytes.Equal(res[:], exp[:]) {
 		t.Errorf("expected %x got %x", exp, res)
 	}
 }
@@ -41,7 +41,7 @@ func TestInsert(t *testing.T) {
 
 	exp := common.Hex2Bytes("8aad789dff2f538bca5d8ea56e8abe10f4c7ba3a5dea95fea4cd6e7c3a1168d3")
 	root := trie.Hash()
-	if !bytes.Equal(root, exp) {
+	if !bytes.Equal(root[:], exp[:]) {
 		t.Errorf("exp %x got %x", exp, root)
 	}
 
@@ -50,7 +50,7 @@ func TestInsert(t *testing.T) {
 
 	exp = common.Hex2Bytes("d23786fb4a010da3ce639d66d5e904a11dbc02746d1ce25029e53290cabf28ab")
 	root = trie.Hash()
-	if !bytes.Equal(root, exp) {
+	if !bytes.Equal(root[:], exp) {
 		t.Errorf("exp %x got %x", exp, root)
 	}
 }
@@ -96,7 +96,7 @@ func TestDelete(t *testing.T) {
 
 	hash := trie.Hash()
 	exp := common.Hex2Bytes("5991bb8c6514148a29db676a14ac506cd2cd5775ace63c30a4fe457715e9ac84")
-	if !bytes.Equal(hash, exp) {
+	if !bytes.Equal(hash[:], exp) {
 		t.Errorf("expected %x got %x", exp, hash)
 	}
 }
@@ -120,7 +120,7 @@ func TestEmptyValues(t *testing.T) {
 
 	hash := trie.Hash()
 	exp := common.Hex2Bytes("5991bb8c6514148a29db676a14ac506cd2cd5775ace63c30a4fe457715e9ac84")
-	if !bytes.Equal(hash, exp) {
+	if !bytes.Equal(hash[:], exp) {
 		t.Errorf("expected %x got %x", exp, hash)
 	}
 }
@@ -150,7 +150,7 @@ func TestReplication(t *testing.T) {
 
 	hash := trie2.Hash()
 	exp := trie.Hash()
-	if !bytes.Equal(hash, exp) {
+	if !bytes.Equal(hash[:], exp[:]) {
 		t.Errorf("root failure. expected %x got %x", exp, hash)
 	}
 
@@ -168,7 +168,9 @@ func TestReset(t *testing.T) {
 	}
 	trie.Commit()
 
-	before := common.CopyBytes(trie.roothash)
+	var before common.Hash
+	before.Set(trie.roothash)
+
 	trie.UpdateString("should", "revert")
 	trie.Hash()
 	// Should have no effect
@@ -177,9 +179,11 @@ func TestReset(t *testing.T) {
 	// ###
 
 	trie.Reset()
-	after := common.CopyBytes(trie.roothash)
 
-	if !bytes.Equal(before, after) {
+	var after common.Hash
+	after.Set(trie.roothash)
+
+	if before != after {
 		t.Errorf("expected roots to be equal. %x - %x", before, after)
 	}
 }
@@ -248,7 +252,7 @@ func BenchmarkGets(b *testing.B) {
 
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		trie.Get([]byte("horse"))
+		trie.GetString("horse")
 	}
 }
 
@@ -263,8 +267,9 @@ func BenchmarkUpdate(b *testing.B) {
 }
 
 type kv struct {
-	k, v []byte
-	t    bool
+	k common.Hash
+	v []byte
+	t bool
 }
 
 func TestLargeData(t *testing.T) {
@@ -272,17 +277,21 @@ func TestLargeData(t *testing.T) {
 	vals := make(map[string]*kv)
 
 	for i := byte(0); i < 255; i++ {
-		value := &kv{common.LeftPadBytes([]byte{i}, 32), []byte{i}, false}
-		value2 := &kv{common.LeftPadBytes([]byte{10, i}, 32), []byte{i}, false}
+		var k1 common.Hash
+		k1.SetBytes([]byte{i})
+		var k2 common.Hash
+		k2.SetBytes([]byte{10, i})
+		value := &kv{k1, []byte{i}, false}
+		value2 := &kv{k2, []byte{i}, false}
 		trie.Update(value.k, value.v)
 		trie.Update(value2.k, value2.v)
-		vals[string(value.k)] = value
-		vals[string(value2.k)] = value2
+		vals[value.k.Str()] = value
+		vals[value2.k.Str()] = value2
 	}
 
 	it := trie.Iterator()
 	for it.Next() {
-		vals[string(it.Key)].t = true
+		vals[it.Key.Str()].t = true
 	}
 
 	var untouched []*kv
@@ -323,7 +332,7 @@ func TestSecureDelete(t *testing.T) {
 
 	hash := trie.Hash()
 	exp := common.Hex2Bytes("29b235a58c3c25ab83010c327d5932bcf05324b7d6b1185e650798034783ca9d")
-	if !bytes.Equal(hash, exp) {
+	if !bytes.Equal(hash[:], exp) {
 		t.Errorf("expected %x got %x", exp, hash)
 	}
 }