fix loginShuffle implementation

internal/entities/user_interface.go

@@ -141,39 +141,30 @@ func (u *UserInterface) AttributeAdjacencyGraph() (map[int]utils.Set[int], error
 }
 
 func (u *UserInterface) LoginShuffle() error {
-	err := u.shuffleKeys()
-	if err != nil {
+	if err := u.shuffleKeys(); err != nil {
 		return err
 	}
-	numbOfSelectedSets := u.Kp.AttrsPerKey / 2
-	if u.Kp.AttrsPerKey&1 == 1 {
-		numbOfSelectedSets += security.Choice[int]([]int{0, 1})
+	keypadSet1, err := u.InterfaceMatrix()
+	if err = u.shuffleKeys(); err != nil {
+		return err
 	}
+	keypadSet2, err := u.InterfaceMatrix()
+	numbOfSelectedSets := u.Kp.AttrsPerKey / 2
 	setIdxs, err := security.RandomPermutation(u.Kp.AttrsPerKey)
 	if err != nil {
 		return err
 	}
 	selectedSets := utils.NewSetFromSlice[int](setIdxs[:numbOfSelectedSets])
 
-	keypadSetView, err := u.SetViewMatrix()
-	if err != nil {
-		return err
-	}
-	interfaceBySet := make([][]int, u.Kp.AttrsPerKey)
-	for idx, attrs := range keypadSetView {
-		if selectedSets.Contains(idx) {
-			err = security.FisherYatesShuffle[int](&attrs)
-			if err != nil {
-				return err
+	for keyIdx, key := range keypadSet1 {
+		for idx, attrIdx := range key {
+			if selectedSets.Contains(attrIdx) {
+				keypadSet1[keyIdx][idx] = keypadSet2[keyIdx][idx]
 			}
 		}
-		interfaceBySet[idx] = attrs
 	}
-	keypadView, err := security.MatrixTranspose(interfaceBySet)
-	if err != nil {
-		return err
-	}
-	u.IdxInterface = security.MatrixToList(keypadView)
+
+	u.IdxInterface = security.MatrixToList(keypadSet1)
 	return nil
 }