In this paper, two password authentication schemes, based on triangle
and straight line encoding, respectively, are proposed. In our schemes
, a one-way function and a strong cryptographic operation such as DES
(data encryption standard) are adopted. Besides, in each scheme, the s
ystem only needs to store a secret key pair, and each user can select
his own password freely. Instead of storing a password verification ta
ble inside the computer system, both methods proposed only have to sto
re a corresponding table of identities, which is used by the computer
System for validating the submitted passwords. Owing to these two sche
mes quickly and efficiently responding to any log-in attempt, they are
suitable for real-time applications. Furthermore, in each scheme, the
system does not need to reconstruct any term of the existing key tabl
e when a new user is inserted into the system. Thus, these two schemes
are suitable for practical implementation.