Cryptography – Communication system using cryptography – Wireless communication
Patent
1992-06-09
1994-10-04
Barron, Jr., Gilberto
Cryptography
Communication system using cryptography
Wireless communication
380 43, 379202, H04L 918, H04M 356
Patent
active
053533518
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.
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Bartoli Paul D.
McNair Bruce E.
AT&T Bell Laboratories
Barron Jr. Gilberto
Indyk Eugene S.
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