diff --git a/src/git.xdrm.io/schastsp/lib/wtime/wtime.go b/src/git.xdrm.io/schastsp/lib/wtime/wtime.go
index 3dec14d..cbbf53e 100644
--- a/src/git.xdrm.io/schastsp/lib/wtime/wtime.go
+++ b/src/git.xdrm.io/schastsp/lib/wtime/wtime.go
@@ -1,6 +1,7 @@
 package wtime
 
 import (
+	"math"
 	"time"
 )
 
@@ -14,10 +15,10 @@ type TimeID struct { ID uint; Parity uint }
 
 /* (1) Generates the current time id
 *
-* @wsize<uint>					Window Size in seconds
+* @wsize<float64>				Window Size in seconds
 *
 ---------------------------------------------------------*/
-func GetID(wsize uint) *TimeID{
+func GenerateID(wsize float64) *TimeID{
 
 	/* (0) Initialise instance */
 	instance := new(TimeID);
@@ -26,13 +27,32 @@ func GetID(wsize uint) *TimeID{
 	if wsize == 0 { return instance }
 
 	/* (2) Get current timestamp */
-	timestamp := uint( time.Now().Unix() );
+	timestamp := float64( time.Now().Unix() );
 
 	/* (3) Calculate the time id */
-	instance.ID = timestamp / wsize;
+	instance.ID = uint( timestamp / wsize );
 
 	/* (4) Calculate parity */
 	instance.Parity = instance.ID % 2;
 
 	return instance;
+}
+
+
+/* (2) Try to guess the received ID from current time and received parity
+*
+* @wsize<float64>				Window Size in seconds
+* @parity<uint>					Received parity
+*
+* @return id<uint>				The guessed time id
+*
+---------------------------------------------------------*/
+func GuessID(wsize float64, parity uint) uint{
+
+	/* (1) Get current time id */
+	var tidNow *TimeID = GenerateID(wsize);
+
+	/* (2) Update ID with tidNow parity difference */
+	return tidNow.ID - uint(math.Abs( float64(tidNow.Parity) - float64(parity) ));
+
 }
\ No newline at end of file
diff --git a/src/git.xdrm.io/schastsp/lib/wtime/wtime_test.go b/src/git.xdrm.io/schastsp/lib/wtime/wtime_test.go
new file mode 100644
index 0000000..d7f9365
--- /dev/null
+++ b/src/git.xdrm.io/schastsp/lib/wtime/wtime_test.go
@@ -0,0 +1,23 @@
+package wtime
+
+import (
+	"time"
+	"testing"
+)
+
+
+func TestGuessing(t *testing.T){
+
+	var windowSize float64 = .5;
+
+	var tid *TimeID = GenerateID(windowSize);
+
+	time.Sleep( time.Duration(windowSize) * time.Second);
+
+	var guessedId uint = GuessID(windowSize, tid.Parity);
+
+	if tid.ID != guessedId {
+		t.Errorf("Wrong guessed id, expected '%d' ; got '%d'", tid.ID, guessedId);
+	}
+
+}
\ No newline at end of file