A combination lock is described where the combination that is used to open the lock is generated on a separate computer system using information that is contained in the lock and a series of steps that combine selected items of the information contained in the lock and alter the results of the results of the combination of the information items. The lock incorporates a computer processor which performs the identical steps to generate an authorized combination after a combination is entered into the lock. When the two combinations match, the lock is enabled for opening. At least some of the information items used in the generation of the combinations change with each successful opening of the lock, rendering the combination generated by the computer system useable for only a single opening of the lock.