Abstract: A secure communication hub (10) relays local communications between low probability of intercept (LPI) user radio equipment (68) and provides a secure interface with a command center (58) through a non-geostationary commercial satellite communication system. The secure communication hub (10) includes different radio interface units (12) for communicating different data formats with the (LPI) user radio equipment (68). Encryption and decryption circuitry (18) provides for different security levels and different keys for the (LPI) user radio equipment. Links with the satellite system are secured using encryption.

Abstract: In a packetized communication system, packets are dispatched to a receiving node (10) for reassembly and presentation to a user. Packets propagating over dynamic paths have propagation variations between subsequent packets. Interactive packetized voice communication systems mandate that end-to-end delays be minimized. This results in voice gaps between an on-time synthesized voice data (602"') and a subsequent delayed synthesized voice data (603"'). Voice gaps are temporarily patched with voice prediction samples and end-to-end timing is adjusted to minimized prediction samples. When packets are lost in the network, prediction packets are substituted and annunciated to a user until valid packets are received.

Abstract: A computer system includes a Key Certification Agency (KCA) (12), a host computer (16), and a number of remote terminals (14). The KCA (12) uses incompatible encryption processes (96, 98) to encrypt session control data and to store the data as various messages (44, 46, 48) in a user token (26). The token (26) may be removably installed in any remote terminal (14). To set up a communication session, the token uncovers one of the messages (48) using a crypto-uncovering agent which is known to the user. This message includes a remote traffic key after deciphering, but the key is never transmitted to the host. The host (16) deciphers the other messages (44, 46) and constructs a host traffic key in response to data contained therein. No plain text is transmitted during the setup or the session.

Abstract: A satellite cellular communications network performs cell-to-cell handoffs between cells of different satellites (30, 32). Inter-satellite handoffs require resynchronization to the prospective propagation timing and Doppler frequency parameters of the prospective satellite. Calculation of these parameters prior to transitioning to the prospective satellite minimizes interruptions to communications. Subscriber units (24) perform handoff parameter calculations while on narrow band communications channels without occupying broadband shared acquisition resources.

Abstract: A tamperproof arrangement for an integrated circuit device. The arrangement includes a package and lid fabricated of heavy metals to prevent X-radiation or infrared detection of circuit operation. Sensors and control circuitry are located on the integrated circuit die itself which detect increased temperature and radiation and clear or zeroize any sensitive information included within the integrated circuit device. Electrode finger grids above and below the integrated circuit die detect physical attempts to penetrate the integrated circuit die. Critical circuit functions are segregated from non-critical functions. Power applied to the integrated circuit device is monitored and separated for critical and non-critical circuit functions.

Abstract: A tamperproof arrangement for an integrated circuit device. The arrangement includes a package and lid fabricated of heavy metals to prevent X-radiation or infrared detection of circuit operation. Sensors and control circuitry are located on the integrated circuit die itself which detect increased temperature and radiation and clear or zeroize any sensitive information included within the integrated circuit device. Electrode finger grids above and below the integrated circuit die detect physical attempts to penetrate the integrated circuit die. Critical circuit functions are segregated from non-critical functions. Power applied to the integrated circuit device is monitored and separated for critical and non-critical circuit functions.

Abstract: An unforgeable personal identification system for identifying users at remote access control sites. The unforgeable personal identification system generates one-way encrypted versions of physically immutable identification credentials (facial photo, retinal scan, voice and finger prints). These credentials are stored on a portable memory device (credit card size). At a remote access control site, the user presents his portable memory device and the encrypted identification credentials are read. The user then submits physically to inputting of his physical identification characteristics to the remote access control site. Comparison is performed with the credentials obtained from the memory device and with the user's physical identity to determine whether to allow or deny access at the remote site.

Abstract: A hardware simulator for simulating digital structures includes a general purpose computer and an improved simulator processor. The improved processor handles an advanced primitive having four inputs and one output and which is capable of representing a memory cell or similar structure. The architecture of the processor provides highly efficient compilation of the input states of a primitive and the primitive evaluator and resolver logic provide the output state in a minimum number of clock cycles. The simulator is a single, low cost unit capable of simulating 64K cell structures with a speed comparable to prior art simulators.