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:
Oct. 04, 1994
Filed:
Jun. 09, 1992
Paul D Bartoli, Red Bank, NJ (US);
Bruce E McNair, Holmdel, NJ (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
Secure teleconferencing between three or more parties is achieved by receiving encrypted information streams from each of the parties to the conference. The encrypted information streams are received in decryption/re-encryption units co-located with a conference bridge established in a telecommunication switching system in a public switched telephone network central office. The decryption/re-encryption units decrypt the information streams and then re-encrypt those information streams in accordance with a common conference encryption algorithm. The re-encryption processes for the information streams are synchronized so that the re-encryption circuitry for all information streams are in the same cryprostate at all times during the re-encryption procedure. The decryption/re-encryption units are located in secure surroundings to protect the unencrypted information streams present in those units. A gating circuit permits only one of the re-encrypted information streams to be input to the conference bridge at a given time. A circuit which simulates the operation of a silent conferee prevents noise bursts from being sent to the conferees during periods of time when all are silent.