Abstract: The present invention relates to electronic locks and electronic locking systems, to electronic locking systems which use remotely encoded keycards and, in particular, to an electronic locking system which utilizes public key cryptography.

Abstract: A data compaction method, for writing data in highly compact binary form in a data storage medium using a microprocessor, compresses serially occurring transaction values in a limited memory space by substituting prefix codes for previously occurring values and for commonly occurring previous values. The previous values are listed and updated on tables by the microprocessor so that they are indexed to the prefix codes adaptively to changing local values and changing common values over time. The data compaction method is particularly suitable for an account card having a limited, non-erasable memory used in an automated transaction terminal for maintaining an account record of transactions in frequently recurring amounts. A postage metering terminal is operated by the account card, in which an initial balance has been written and each purchase of postage is recorded. A current balance is recomputed by parsing the previously recorded data.

Abstract: Disclosed is a clutch mechanism suitable for use in an electronic lock. The clutch mechanism requires minimum electronic current draw for operation by utilizing mechanical power applied to operate the lock to engage the clutch mechanism. A camming device in combination with a timed function motion sensor and latching solenoid released interference shutter accomplishes the object of the invention.