An enhanced simple secure remote password authentication scheme without using cryptography

Since the eavesdropping resistant remote password authentication schemes based on cryptography require that certain cryptosystems and/or cryptographic hash functions have to be implemented in the user´s login device. Thus, many eavesdropping resistant remote password authentication schemes without using cryptography have been proposed. However, most existing eavesdropping resistant remote password authentication schemes without using cryptography are time-consuming, hard to learn, difficult to use, and/or difficult to implement. Recently, Yeh et al. have proposed a simple and efficient eavesdropping resistant remote password authentication scheme without using cryptography, ColorPallete. Unfortunately, the resistance of ColorPallete to eavesdropping is unsatisfactory. In this paper, we propose an enhanced version of ColorPallete. The eavesdropping resistance and the password space of the proposed scheme are superior to the ones of ColorPallete while the resistance to accidental login is kept unchanged at the cost of additionally memorizing one pass-icon.