On the matsumoto and Imai’s human identification scheme

Abstract

At Eurocrypt’Sl, Matsumoto and Imai presented a human identification scheme for insecure channels, which is suitable for human ability of memorizing and processing a short secret. It prevents an intruder from peeping user in typing password on terminal connected to the central computer. However, in this paper, we are going to propose a new attack, called the replay challenge attack, where a malicious terminal pretends to be the host and replays the host’s challenges to reveal the secret password. A modified scheme will be proposed to avoid this attack.