diff --git a/api/alldoormen.go b/api/alldoormen.go
index eeb9438..ff06961 100644
--- a/api/alldoormen.go
+++ b/api/alldoormen.go
@@ -6,13 +6,13 @@ import (
 )
 
 func GetAllDoormen(w http.ResponseWriter, request *http.Request) {
-	fmt.Fprint(w, `{"doormen" :[`)
 	doormenIds := conn.GetAllDoormen()
 	buff := <-doormenIds
 	if buff == nil {
-		fmt.Fprint(w, "]}")
+		fmt.Fprint(w, `{"doormen" :[]}`)
 		return
 	}
+	fmt.Fprint(w, `{"doormen" :[`)
 	for doormanId := range doormenIds {
 		fmt.Fprint(w, getDoormenIdsAsJson(buff)+`,`)
 		buff = doormanId
diff --git a/api/alldoormen_test.go b/api/alldoormen_test.go
index aeae2b5..dcefc20 100644
--- a/api/alldoormen_test.go
+++ b/api/alldoormen_test.go
@@ -29,7 +29,7 @@ func TestGetAllDoormen(t *testing.T) {
 	GetAllDoormen(w, req)
 
 	d := json.NewDecoder(w.Body)
-	m := make(map[string][]*doormen.DoormanDefinition)
+	m := make(map[string][]*doormen.DoormanId)
 
 	if err := d.Decode(&m); err != nil {
 		t.Error(err)
diff --git a/api/createdoorman.go b/api/createdoorman.go
index bb1e882..dc0c0f3 100644
--- a/api/createdoorman.go
+++ b/api/createdoorman.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"github.com/didiercrunch/doormanserver/doormen"
+	"github.com/didiercrunch/doormanserver/shared"
 	"gopkg.in/mgo.v2/bson"
 	"net/http"
 )
@@ -30,6 +31,6 @@ func CreateDoorman(w http.ResponseWriter, request *http.Request) {
 		return
 	}
 	go publisher.Emit(wdef.Id, wdef)
-	w.Header().Set("location", "/api/doormen/"+wdef.Id.Hex())
+	w.Header().Set("location", "/api/doormen/"+shared.ObjectIdToPublicId(wdef.Id))
 	w.WriteHeader(201)
 }
diff --git a/api/createdoorman_test.go b/api/createdoorman_test.go
index 00b29e4..4f16596 100644
--- a/api/createdoorman_test.go
+++ b/api/createdoorman_test.go
@@ -3,6 +3,7 @@ package api
 import (
 	"bytes"
 	"github.com/didiercrunch/doormanserver/inmemoryconnector"
+	"github.com/didiercrunch/doormanserver/shared"
 	"gopkg.in/mgo.v2/bson"
 	"net/http"
 	"net/http/httptest"
@@ -11,7 +12,12 @@ import (
 )
 
 func GetIdFromLocation(p string) bson.ObjectId {
-	return bson.ObjectIdHex(path.Base(p))
+	if id, err := shared.PublicIdToObjectId(path.Base(p)); err != nil {
+		panic(err)
+	} else {
+		return id
+	}
+
 }
 
 func TestCreateDoorman(t *testing.T) {
diff --git a/api/util.go b/api/util.go
index 7295664..8a9af19 100644
--- a/api/util.go
+++ b/api/util.go
@@ -3,6 +3,7 @@ package api
 import (
 	"fmt"
 	"github.com/didiercrunch/doormanserver/doormen"
+	"github.com/didiercrunch/doormanserver/shared"
 	"github.com/gorilla/mux"
 	"gopkg.in/mgo.v2/bson"
 	"log"
@@ -10,15 +11,16 @@ import (
 )
 
 func getDoormenIdsAsJson(id *doormen.DoormanId) string {
-	return fmt.Sprintf(`{"name": "%v", "id": "%v", "url": "/api/doormen/%v"}`, id.Name, id.Id.Hex(), id.Id.Hex())
+	publicId := shared.ObjectIdToPublicId(id.Id)
+	return fmt.Sprintf(`{"name": "%v", "id": "%v", "url": "/api/doormen/%v"}`, id.Name, publicId, publicId)
 }
 
 func getDoormanIdFromRequest(w http.ResponseWriter, request *http.Request) bson.ObjectId {
 	id := mux.Vars(request)["id"]
-	if !bson.IsObjectIdHex(id) {
+	if id, err := shared.PublicIdToObjectId(id); err != nil {
 		return ""
 	} else {
-		return bson.ObjectIdHex(id)
+		return id
 	}
 }
 
diff --git a/doormen/doormen.go b/doormen/doormen.go
index e0c8ddc..e9a0eed 100644
--- a/doormen/doormen.go
+++ b/doormen/doormen.go
@@ -17,11 +17,6 @@ type DoormanValue struct {
 	Probability *big.Rat `json:"probability"`
 }
 
-type doormanValue struct {
-	Name        string
-	Probability string
-}
-
 type DoormanId struct {
 	Id   bson.ObjectId `json:"id,omitempty" bson:"_id"`
 	Name string        `json:"name" bson:"name"`
@@ -35,10 +30,10 @@ func (wId *DoormanId) AsJson() string {
 }
 
 type DoormanDefinition struct {
-	Id          bson.ObjectId   `json:"id,omitempty" bson:"_id"`
-	Name        string          `json:"name" bson:"name"`
-	Values      []*DoormanValue `json:"values" bson:"values"`
-	OwnerEmails []string        `json:"emails" bson:"emails"`
+	Id          bson.ObjectId   `bson:"_id"`
+	Name        string          `bson:"name"`
+	Values      []*DoormanValue `bson:"values"`
+	OwnerEmails []string        `bson:"emails"`
 }
 
 func NewDoormanDefinition(name string, ownerEmails ...string) *DoormanDefinition {
diff --git a/doormen/encoding.go b/doormen/encoding.go
index ede7879..dc877ae 100644
--- a/doormen/encoding.go
+++ b/doormen/encoding.go
@@ -1,10 +1,17 @@
 package doormen
 
 import (
+	"encoding/json"
+	"github.com/didiercrunch/doormanserver/shared"
 	"gopkg.in/mgo.v2/bson"
 	"math/big"
 )
 
+type doormanValue struct {
+	Name        string
+	Probability string
+}
+
 func (val *DoormanValue) GetBSON() (interface{}, error) {
 	ret := &doormanValue{val.Name, ""}
 	txt, err := val.Probability.MarshalText()
@@ -24,3 +31,60 @@ func (val *DoormanValue) SetBSON(raw bson.Raw) error {
 	val.Probability = new(big.Rat)
 	return val.Probability.UnmarshalText([]byte(v.Probability))
 }
+
+type jsonDoormanDefinition struct {
+	Id          string          `json:"id,omitempty"`
+	Name        string          `json:"name"`
+	Values      []*DoormanValue `json:"values"`
+	OwnerEmails []string        `json:"emails"`
+}
+
+func (dm *DoormanDefinition) MarshalJSON() ([]byte, error) {
+	jdm := new(jsonDoormanDefinition)
+	jdm.Name = dm.Name
+	jdm.OwnerEmails = dm.OwnerEmails
+	jdm.Values = dm.Values
+	jdm.Id = shared.ObjectIdToPublicId(dm.Id)
+	return json.Marshal(jdm)
+}
+
+func (dm *DoormanDefinition) UnmarshalJSON(data []byte) error {
+	jsm := new(jsonDoormanDefinition)
+	var err error
+	if err = json.Unmarshal(data, jsm); err != nil {
+		return err
+	}
+	if dm.Id, err = shared.PublicIdToObjectId(jsm.Id); err != nil {
+		return err
+	}
+	dm.Name = jsm.Name
+	dm.Values = jsm.Values
+	dm.OwnerEmails = jsm.OwnerEmails
+	return nil
+}
+
+type jsonDoormanId struct {
+	Name string `json:"name"`
+	Id   string `json:"id"`
+}
+
+func (did *DoormanId) MarshalJSON() ([]byte, error) {
+	jdid := new(jsonDoormanId)
+	jdid.Name = did.Name
+	jdid.Id = shared.ObjectIdToPublicId(did.Id)
+	return json.Marshal(jdid)
+
+}
+
+func (did *DoormanId) UnmarshalJSON(data []byte) error {
+	jdid := new(jsonDoormanId)
+	if err := json.Unmarshal(data, jdid); err != nil {
+		return err
+	}
+	var err error
+	if did.Id, err = shared.PublicIdToObjectId(jdid.Id); err != nil {
+		return err
+	}
+	did.Name = jdid.Name
+	return nil
+}
diff --git a/doormen/encoding_test.go b/doormen/encoding_test.go
index 3f5b68b..e3d6a64 100644
--- a/doormen/encoding_test.go
+++ b/doormen/encoding_test.go
@@ -1,6 +1,7 @@
 package doormen
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"gopkg.in/mgo.v2/bson"
 	"reflect"
@@ -22,6 +23,42 @@ func TestJsonEncoding(t *testing.T) {
 	}
 }
 
+func TestJsonEncodingWithEmptyIds(t *testing.T) {
+	dmd := QuickNewDoormanDefinition("test json", "1/4", "3/4")
+	dmd.Id = ""
+	data, err := json.Marshal(dmd)
+	if err != nil {
+		t.Error(err)
+	}
+	dmd2 := new(DoormanDefinition)
+	if err = json.Unmarshal(data, dmd2); err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(dmd2, dmd) {
+		t.Error()
+	}
+}
+
+func TestJsonIdFormatToBeCompatibleWithSiphashKey(t *testing.T) {
+	dmd := QuickNewDoormanDefinition("test json", "1/4", "3/4")
+	data, err := json.Marshal(dmd)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	m := make(map[string]interface{})
+	if err = json.Unmarshal(data, &m); err != nil {
+		t.Error(err)
+		return
+	}
+	if b, err := base64.URLEncoding.DecodeString(m["id"].(string)); err != nil {
+		t.Error(err)
+		return
+	} else if len(b) != 16 {
+		t.Error("siphash requires a 16 bytes (128 bits) key not ", len(b))
+	}
+}
+
 func TestBsonEncoding(t *testing.T) {
 	dmd := QuickNewDoormanDefinition("test bson", "1/4", "3/4")
 	data, err := bson.Marshal(dmd)
@@ -36,3 +73,19 @@ func TestBsonEncoding(t *testing.T) {
 		t.Error()
 	}
 }
+
+func TestDoormanIdJsonEncoding(t *testing.T) {
+	did := &DoormanId{bson.NewObjectId(), "hahaha"}
+	data, err := json.Marshal(did)
+	if err != nil {
+		t.Error(err)
+	}
+	did2 := new(DoormanId)
+	if err = json.Unmarshal(data, did2); err != nil {
+		t.Error(err)
+	}
+	if !reflect.DeepEqual(did2, did) {
+		t.Error()
+	}
+
+}
diff --git a/server.go b/server.go
index f7d2862..684e9dc 100644
--- a/server.go
+++ b/server.go
@@ -17,7 +17,7 @@ func GetAddressToServe() string {
 	return params.Host + ":" + strconv.Itoa(params.Port)
 }
 
-func serveStatic2(w http.ResponseWriter, request *http.Request) {
+func serveStatic(w http.ResponseWriter, request *http.Request) {
 	filepath := request.URL.Path
 	w.Header().Set("Cache-Control", "private, max-age=0, no-cache")
 	http.ServeFile(w, request, path.Join(STATIC_DIR_PATH, filepath))
@@ -26,7 +26,7 @@ func serveStatic2(w http.ResponseWriter, request *http.Request) {
 func main() {
 	mux := http.NewServeMux()
 	mux.Handle("/api/", api.Create("/api"))
-	mux.HandleFunc("/", serveStatic2)
+	mux.HandleFunc("/", serveStatic)
 
 	address := GetAddressToServe()
 	fmt.Println("server running at", address)
diff --git a/shared/params.go b/shared/params.go
index 3bc99a6..36fc673 100644
--- a/shared/params.go
+++ b/shared/params.go
@@ -69,7 +69,7 @@ func (p *Params) InsertDefaultValues() *Params {
 }
 
 func LoadFromYamlFile(fileName string) (*Params, error) {
-	if !Exists(fileName) {
+	if !exists(fileName) {
 		return new(Params).InsertDefaultValues(), nil
 	}
 	data, err := ioutil.ReadFile(fileName)
diff --git a/shared/util.go b/shared/util.go
index 1b83ab1..c6b6418 100644
--- a/shared/util.go
+++ b/shared/util.go
@@ -1,8 +1,17 @@
 package shared
 
-import "os"
+import (
+	"crypto/subtle"
+	"encoding/base64"
+	"errors"
+	"github.com/dchest/siphash"
+	"gopkg.in/mgo.v2/bson"
+	"os"
+)
 
-func Exists(name string) bool {
+var idHashKey []byte = []byte("semi-private-key")
+
+func exists(name string) bool {
 	if _, err := os.Stat(name); err != nil {
 		if os.IsNotExist(err) {
 			return false
@@ -10,3 +19,38 @@ func Exists(name string) bool {
 	}
 	return true
 }
+
+func validateId(id []byte) error {
+	if len(id) != 16 {
+		return errors.New("valid ids are 16 bytes (126 bit) long.")
+	}
+	h := siphash.New(idHashKey)
+	h.Write(id[4:16])
+	if subtle.ConstantTimeCompare(h.Sum(nil)[0:4], id[0:4]) != 1 {
+		return errors.New("invalid id checksum")
+	}
+	return nil
+}
+
+func ObjectIdToPublicId(id bson.ObjectId) string {
+	if id == "" {
+		return ""
+	}
+	h := siphash.New(idHashKey)
+	h.Write([]byte(id))
+	return base64.URLEncoding.EncodeToString(append(h.Sum(nil)[0:4], []byte(id)...))
+}
+
+func PublicIdToObjectId(id string) (bson.ObjectId, error) {
+	if id == "" {
+		return "", nil
+	}
+	cypher, err := base64.URLEncoding.DecodeString(id)
+	if err != nil {
+		return "", err
+	}
+	if err := validateId(cypher); err != nil {
+		return "", err
+	}
+	return bson.ObjectId(cypher[4:16]), nil
+}