Device for transmission of information at varying frequency

Differential correlator for spread spectrum communication...

Digital communication system including an error correcting...

Digital radio with security system for selectively enabling...

Digital signal transmission system

Digital trading card, system, and method

Digital transmission system

Direct sequence spread spectrum communication system with...

Distributed information system having automatic invocation...

Diversity receiver in a cdma cellular telephone system

Duplex analog scrambler

E-mail firewall with stored key encryption/decryption

Electron beam traverse of narrow aperture in barrier...

Electronic enciphering-and deciphering apparatus in the form...

Electronic funds transfer instruments

Encoding of information

Encrypted mail monitoring and data retrieval system

Encryption and authentication methods and apparatus for...

Encryption system key distribution method and apparatus

Encryption with selective disclosure of protocol identifiers