| 摘要 |
<p>An active coded hardware device in the form of an active presettable counter circuit which contains an established preset code is plugged into a computer and is used for protecting software used with the computer. At least one additional function must be performed either before or after the counter is used in order to enable the actively coded hardware device to provide an output and if no output is generated, then the program contained in the software will not be permitted to continue insuring that the software is properly protected. In the example of a given function performed prior to the counter, a pair of bit streams, one of which may be from a secret stored non-volatile memory, such as a password are compared, which varies the count in the counter during each match of the inputs and resets the counter when a match does not occur. Accordingly, a predetermined correct succession of responses is required, or no output occurs dismissing one of the sources as an improper password. In the other form, the count in the counter is changed by a source of clock pulses whose output is fed to an addressable memory containing an access code which is not generated unless a proper code input from the counter is provided. Accordingly, in either the use before or after a function is performed, both the function and counter are combined in a manner which ensures that the software is properly protected at all times.</p> |
