Electronic door lock key re-sequencing function
US4870400A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 1988 |
| Grant date | Sep 26, 1989 |
| Priority date | — |
| Expiry date | Jan 26, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/27
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An electronic security device has at least one lock and a control center for generating keys to the lock. When a new key is generated, a new (second) combination is generated by applying a predetermined algorithm and randomly generated (first) calculation data to the previous (first) combination. To calculate a next new (third) combination, another randomly generated (second) calculation data is applied to the second combination using the same algorithm. The control center stores, on the key, the third combination, and the second calculation data used to obtain it and the first calculation data used to obtain the second combination. At the lock, the third combination is compared with a stored combination and if there is no match, the lock calculates a possible second combination by applying an algorithm, which is the inverse of the predetermined algorithm, to the stored combination using the second calculation data read from the key. If there is still no match, the lock calculates a possible first combination using the first calculation data read from the key. If there is still no match, the lock will not be opened. In another embodiment of the invention, a check-in time and a chec…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.