Employing recent results of M. Ali Khan we provide an infinitedimensional version of the Fatou Lemma, which includes as a special case the result of Khan and Majumdar [15].

Liaqat Ali 1,2, Saeed Islam 1, Taza Gul 1, Ilyas Khan 3, L. C. C. Dennis 4,∗ , Waris Khan5 and Aurangzeb Khan 6 1 Department of Mathematics, Abdul Wali Khan University, Mardan 23200, KPK, Pakistan; [email protected] (L.A.); [email protected] (S.I.); [email protected] (T.G.) 2 Department of Electrical Engineering, CECOS University, Peshawer 25000, KPK, Pakistan 3 Department of Mathem...

Biometric-based authentication systems are widely deployed for person identification. Recently, an improved scheme for flexible biometrics remote user authentication was proposed by Khan and Zhang. In this paper, we demonstrate that Khan-Zhang’s scheme is still vulnerable to the following two attacks: (1) It is insecure to parallel session attack in which an adversary without knowing a legal us...