Computer-telephone security device

A computer access security system for authorizing access to a host computer from a remote terminal, comprising a master unit coupled to the host computer, a slave unit coupled to the remote terminal, the slave unit including means for storing a plurality of slave unit passwords and a plurality of algorithms, the master unit including means for storing a plurality of master unit passwords and the same plurality of algorithms, the slave unit including means for transmitting each slave unit password to the master unit, the master unit including means for comparing the received slave unit passwords with the stored master unit passwords, one of the slave and master units including means for generating access data upon the successful comparison of the slave unit passwords received by the master unit with the stored master unit passwords and transmitting it to the other of the master and slave units, the master unit including means for operating upon the access data with each of its stored algorithms to derive a plurality of new master unit passwords, the slave unit including means for operating upon the access data with each of its stored algorithms to derive a plurality of new slave unit passwords identical to the new master unit passwords, the master unit having means for combining the new master unit passwords, the slave unit having means for combining the new slave unit passwords, one of the master and slave units having means for transmitting its combined new passwords to the other of the master and slave units, the other of the master and slave units including means for comparing the combined new master unit passwords with the combined new slave unit passwords and sending an acknowledgment of the results of the comparison to the transmitting unit, the master and slave units including means for permitting the remote terminal access to the host computer when the received slave unit passwords match the stored master unit passwords and the combined new master unit passwords matches the combined new slave unit passwords, the master and slave units including means for replacing their stored passwords with the new master and slave unit passwords, respectively, when the combined new master unit passwords matches the combined new slave unit passwords, the new master unit passwords and the new slave unit passwords being generated during a log-on sequence wherein the remote terminal is attempting to access the host computer and the master unit passwords and the slave unit passwords comprise the new master unit passwords and the new slave unit passwords, respectively, which were produced by the master unit and slave unit, respectively, during an immediately preceding log-on sequence where the remote terminal successfully obtained access to the host computer.