diff --git a/auth/auth.go b/auth/auth.go
index 9c762a6..58bda33 100644
--- a/auth/auth.go
+++ b/auth/auth.go
@@ -11,12 +11,25 @@ import (
 var (
 	// ErrInvalidPassword returned when password and hash don't match
 	ErrInvalidPassword = fmt.Errorf("Invalid password")
+	// ErrInvalidSecret returned when cookie's secret is don't match
+	ErrInvalidSecret = fmt.Errorf("Invalid secret")
 	// ErrCorrupted returned when session have been corrupted
 	ErrCorrupted = fmt.Errorf("Corrupted session")
 )
 
+// UserBackend interface for user backend
+type UserBackend interface {
+	Get(username string) (User, error)
+}
+
+// User interface for user
+type User interface {
+	GetHash() string
+}
+
 // Authorizer handle sesssion
 type Authorizer struct {
+	backend    UserBackend
 	cookiejar  *sessions.CookieStore
 	cookieName string
 	peeper     string
@@ -25,8 +38,9 @@ type Authorizer struct {
 
 // New Authorizer peeper is like a salt but not stored in database,
 // cost is the bcrypt cost for hashing the password
-func New(peeper, cookieName, cookieKey string, cost int) *Authorizer {
+func New(backend UserBackend, peeper, cookieName, cookieKey string, cost int) *Authorizer {
 	return &Authorizer{
+		backend:    backend,
 		cookiejar:  sessions.NewCookieStore([]byte(cookieKey)),
 		cookieName: cookieName,
 		peeper:     peeper,
@@ -44,18 +58,31 @@ func (a *Authorizer) GenHash(password string) (string, error) {
 }
 
 // Login cheks password and updates cookie info
-func (a *Authorizer) Login(rw http.ResponseWriter, req *http.Request, username, hash, password string) error {
+func (a *Authorizer) Login(rw http.ResponseWriter, req *http.Request, username, password string) error {
 	cookie, err := a.cookiejar.Get(req, a.cookieName)
 	if err != nil {
 		return err
 	}
 
-	err = bcrypt.CompareHashAndPassword([]byte(hash), []byte(password+a.peeper))
+	u, err := a.backend.Get(username)
+	if err != nil {
+		return err
+	}
+
+	err = bcrypt.CompareHashAndPassword([]byte(u.GetHash()), []byte(password+a.peeper))
 	if err != nil {
 		return ErrInvalidPassword
 	}
 
 	cookie.Values["username"] = username
+
+	// genereate secret
+	b, err := bcrypt.GenerateFromPassword([]byte(u.GetHash()), a.cost)
+	if err != nil {
+		return err
+	}
+	cookie.Values["secret"] = string(b)
+
 	err = cookie.Save(req, rw)
 	if err != nil {
 		return err
@@ -69,7 +96,8 @@ func (a *Authorizer) Logout(rw http.ResponseWriter, req *http.Request) error {
 	if err != nil {
 		return err
 	}
-	cookie.Values["username"] = ""
+	cookie.Values["username"] = nil
+	cookie.Values["secret"] = nil
 	cookie.Options.MaxAge = -1 // kill the cookie
 	err = cookie.Save(req, rw)
 	if err != nil {
@@ -79,20 +107,43 @@ func (a *Authorizer) Logout(rw http.ResponseWriter, req *http.Request) error {
 }
 
 // CurrentUser returns the logged in username from session
-func (a *Authorizer) CurrentUser(rw http.ResponseWriter, req *http.Request) (string, error) {
+func (a *Authorizer) CurrentUser(rw http.ResponseWriter, req *http.Request) (User, error) {
 	cookie, err := a.cookiejar.Get(req, a.cookieName)
 	if err != nil {
-		return "", err
+		return nil, err
+	}
+	if cookie.IsNew {
+		return nil, nil
 	}
 
-	username := cookie.Values["username"]
-
-	if !cookie.IsNew && username != nil {
-		str, ok := username.(string)
-		if !ok {
-			return "", ErrCorrupted
-		}
-		return str, nil
+	usernameTmp := cookie.Values["username"]
+	if usernameTmp == nil {
+		return nil, nil
 	}
-	return "", nil
+	username, ok := usernameTmp.(string)
+	if !ok {
+		return nil, ErrCorrupted
+	}
+
+	u, err := a.backend.Get(username)
+	if err != nil {
+		return nil, err
+	}
+
+	// Check secret
+	hash := u.GetHash()
+	secretTmp := cookie.Values["secret"]
+	if secretTmp == nil {
+		return nil, nil
+	}
+	secret, ok := secretTmp.(string)
+	if !ok {
+		return nil, ErrCorrupted
+	}
+	err = bcrypt.CompareHashAndPassword([]byte(secret), []byte(hash))
+	if err != nil {
+		return nil, ErrInvalidSecret
+	}
+
+	return u, nil
 }
diff --git a/auth/auth_test.go b/auth/auth_test.go
index 8f95d39..55e7c1c 100644
--- a/auth/auth_test.go
+++ b/auth/auth_test.go
@@ -23,9 +23,40 @@ const (
 	hash     = "$2a$10$eVye8xbs6nj4TWnlTmifRuBsAU3F2hkxEcFz9WXdYjUuE6uKLVuzK"
 )
 
+type user struct {
+	username string
+	password string
+	hash     string
+}
+
+func (u *user) GetHash() string {
+	return u.hash
+}
+
+type Backend struct {
+	user *user
+}
+
+func (b *Backend) Get(username string) (User, error) {
+	if username == b.user.username {
+		return b.user, nil
+	}
+	return nil, fmt.Errorf("invalid username")
+}
+
+func getBackend() *Backend {
+	return &Backend{
+		user: &user{
+			username: username,
+			password: password,
+			hash:     hash,
+		},
+	}
+}
+
 func login(w http.ResponseWriter, r *http.Request) {
-	a := New(peeper, cookie, key, cost)
-	err := a.Login(w, r, username, hash, password)
+	a := New(getBackend(), peeper, cookie, key, cost)
+	err := a.Login(w, r, username, password)
 	if err != nil {
 		fmt.Fprintf(w, "%s", err)
 		w.WriteHeader(http.StatusInternalServerError)
@@ -35,7 +66,7 @@ func login(w http.ResponseWriter, r *http.Request) {
 
 }
 func logout(w http.ResponseWriter, r *http.Request) {
-	a := New(peeper, cookie, key, cost)
+	a := New(getBackend(), peeper, cookie, key, cost)
 	err := a.Logout(w, r)
 	if err != nil {
 		fmt.Fprintf(w, "%s", err)
@@ -45,7 +76,7 @@ func logout(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusOK)
 }
 func check(w http.ResponseWriter, r *http.Request) {
-	a := New(peeper, cookie, key, cost)
+	a := New(getBackend(), peeper, cookie, key, cost)
 	u, err := a.CurrentUser(w, r)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)
@@ -53,7 +84,14 @@ func check(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	w.WriteHeader(http.StatusOK)
-	fmt.Fprintf(w, "%s", u)
+	if u != nil {
+		usr, ok := u.(*user)
+		if !ok {
+			fmt.Fprintf(w, "Invalid user type")
+			return
+		}
+		fmt.Fprintf(w, "%s", usr.username)
+	}
 
 }