The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 27, 1988
Filed:
Dec. 11, 1986
The Plessey Company, plc, Ilford, GB;
Abstract
The Telecommunications system includes at least two exchanges and a plurality of user equipments. Each equipment includes a store for holding a user variable data word particular to that user. Each exchange is provided with a store for holding all the user variable data words of the users connected to it, and each exchange is also provided with its own random variable data word. When a first user makes a secure call to a second user, the first user equipment encrypts the call using its particular variable data word and sends the encrypted data to its own exchange. The exchange decrypts the call using the particular user variable data word that will be used for the call. The exchange encrypts the random variable data word with the particular user variable data word and returns it to the first user. The exchange also sends the random variable data word to the second user's exchange which encrypts it with the user variable data word particular to the second user, and sends it to the second user.