Abstract: A plurality of push-button switches are located on a locking structure which also includes an encoding circuit having a specific code set therein requiring operation of the push-buttons in a predetermined sequence. Operation of the first coded button starts an energy timing circuit which provides electrical energy required to permit the lock to open, the energy timing circuit de-energizing the mechanism after a predetermined time so that the electronic decoding circuit automatically blocks the lock unless the proper code was entered within the predetermined time interval, and the appropriate first push-button, providing for energization of the entire system, was first operated. The timing circuit preferably is a capacitor which is charged upon operation of the first push-button, encoded to be first operated and which, if the proper code is punched, provides energy to a solenoid coil which releases a locking element if the proper code permits discharge of the capacitor through the solenoid.