| 5432848 |
DES encryption and decryption unit with error checking |
| Jul-11-1995 |
An improved DES unit internally checks whether the DES algorithm is being performed without error. A standard DES algorithm performs an initial permutation of input data and then multiple rounds or iterations... |
| 5400404 |
Modulation/demodulation circuit and communication system utilizing the same |
| Mar-21-1995 |
The present invention provides a modulation/ demodulation circuit and a communication system utilizing the modulation/demodulation circuit. The modulation/ demodulation circuit can be operated in either... |
| 5392357 |
Secure telecommunications |
| Feb-21-1995 |
A security node disposed in the telecommunications network connecting calling and called parties transforms information (which can be voice, data, facsimile, video and other types of calls or messages)... |
| 5377265 |
Parallel additive scrambler and descrambler |
| Dec-27-1994 |
Parallel working additive scramblers produce a predetermined pseudorandom sequence of length L in a word generator, which consists of an N-stage shift register. To obtain more than N parallel located pseudorandom... |
| 5365588 |
High speed encryption system and method |
| Nov-15-1994 |
A general purpose, high-speed encryption system and method, based on a linear feedback shift register (LFSR) that provides inputs to one or more mathematically independent nonlinear output functions, resulting... |
| 5361302 |
Method for encryption sync compression in an encrypted radio telephone interconnect system |
| Nov-1-1994 |
A method for transparently coupling an encrypted two-way RF communication unit (100) with an encrypted landline communication unit (104). An RF message comprised of a plurality of data frames (401,402,... |
| 5353351 |
Secure teleconferencing |
| Oct-4-1994 |
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... |
| 5351136 |
Facsimile apparatus and method for sending and receiving private information |
| Sep-27-1994 |
A FAX-receiving-and-output device for secret information and method therefore, which comprises a first and a second information transmission channels for transmitting non-secret information and secret... |
| 5335275 |
Television scrambler |
| Aug-2-1994 |
A video encryption/decryption system in which lines of video information are stored in digitised form in a block of RAM memory, and are typically shuffled in groups of 32 lines by pivot reading information... |
| 5311596 |
Continuous authentication using an in-band or out-of-band side channel |
| May-10-1994 |
A re-authentication procedure between the modems of a public switched telephone network (PSTN) data connection, which is between a computer facility and a user, provides a secure method for protecting... |
| 5305384 |
Apparatus, system and method for transmitting secure signals over narrow spaced channels |
| Apr-19-1994 |
An encryption/decryption device, system and method for providing secure communication over a communication channel. The encryption device includes a radio interface unit connected to a conventional radio,... |
| 5291515 |
Spread spectrum communication device |
| Mar-1-1994 |
On the transmitter side, data to be transmitted are converted into a plurality of parallel data sets by a serial-parallel converter 101 and spread spectrum modulation is effected by means of PN code generators... |
| 5267316 |
Synchronous system for parallel data scrambling |
| Nov-30-1993 |
Of the type formed by a pseudorandom code generator and a block that performs the synchronizing and the scrambling in parallel which, in addition to the initialization signal, receives as inputs the set... |
| 5253293 |
Adaptive data ciphering/deciphering apparatuses and data communication system using these apparatuses |
| Oct-12-1993 |
A data communication system adaptable to a ciphered data communication includes a data transmission line (3) for transmitting ciphered or non-ciphered data between a data transmitting device and a data... |
| 5235643 |
Satellite receiver retuning system |
| Aug-10-1993 |
A remotely retunable receiver for use in a satellite video programming distribution system includes the capability to retune groups of subscribers to different satellite feeds during a blackout of a video... |
| 5233626 |
Repeater diversity spread spectrum communication system |
| Aug-3-1993 |
A repeater diversity spread spectrum communication system provides substantially fade free communications between a transmitter (1) and a receiver (7). A transmitted signal is relayed through a plurality... |
| 5231662 |
Method and device for enciphering data to be transferred and for deciphering the enciphered data, and a computer system comprising such a device |
| Jul-27-1993 |
Method and device for enciphering data words of a word width of n bits, in particular data words to be written in a computer storage, wherein a product cipher circuit comprises alternately one from a plurality... |
| 5228054 |
Power-of-two length pseudo-noise sequence generator with fast offset adjustment |
| Jul-13-1993 |
A maximal length linear sequence pseudorandom noise (PN) sequence generator for generating an augmented length PN sequence of length 2.sup.N. The PN generator includes circuitry for generating a PN sequence... |
| 5214694 |
Scramble signal transmission system for earth station of communication satellite |
| May-25-1993 |
A system for transmitting a scramble signal for a sky port scramble system including an organization center for organizing data relating to customers etc. and first and second control units each having... |
| 5210794 |
Apparatus and method for establishing crypto conferences on a telecommunications network |
| May-11-1993 |
A method to establish a speech conference connection between a group of conference participating nodes (2,4,8) which can freely be selected among a greater plurality of nodes (2-9) having conference facilities,... |
| 5185799 |
Parallel scrambler used in SONET data transmission |
| Feb-9-1993 |
A data scrambler circuit which adds the SONET polynomial 1+X.sup.6 +X.sup.7 to data in a parallel format to thereby reduce circuitry clock rates to one-eighth the line rate, which reduces power consumption... |
| 5148480 |
Decoder |
| Sep-15-1992 |
A decoder having a plurality of outputs (R.sub.0 -Rn) each associated with a particular output valve is arranged to add together two binary numbers (A, B) and to select one of the outputs in dependence... |
| 5101432 |
Signal encryption |
| Mar-31-1992 |
Method and apparatus for encrypting and subsequently decrypting an analog or digital signal are disclosed. During encryption the signal waveform is transformed by a substantially continuous non-linear... |
| 5086467 |
Dummy traffic generation |
| Feb-4-1992 |
In a secure communication system, a method for generating dummy traffic to forestall cryptanalytic attack by traffic analysis. Both the dummy traffic signal and certain characteristics of the dummy transmissions,... |
| 5060264 |
Radiotelephone controller configured for coresident secure and nonsecure modes |
| Oct-22-1991 |
A controller for a radiotelephone having the capability of operation in both a secure mode for call authorization and a nonsecure mode for user interface is disclosed. The nonsecure mode and secure mode... |
| 5008937 |
Scrambled-communication system using adaptive transversal filters for descrambling received signals |
| Apr-16-1991 |
In a scrambled-communication system, a transmitting station generates a scrambling noise having a periodically-recurrent series of noise patterns and scrambles an information signal by simply summing the... |
| 4993067 |
Secure satellite over-the-air rekeying method and system |
| Feb-12-1991 |
A secure satellite over-the-air rekeying method and system are shown. This system provides a geometric filter for allowing message input to a satellite from ground stations having a particular predefined... |
| 4972479 |
Method and apparatus for providing privacy/security in a communication system |
| Nov-20-1990 |
Apparatus and methods are disclosed for providing privacy on communications systems which include radio links, such as cellular telephone, marine radiotelephone, IMTS, and RDSS systems, in a manner which... |
| 4965766 |
Digital input/out circuit capable of sending and receiving data in different modes |
| Oct-23-1990 |
A digital input/output circuit to be connected between an internal data bus composed of 2.sup.n signal lines (n is zero or a positive integer) and 2.sup.n external terminals includes an output port for... |
| 4959863 |
Secret speech equipment |
| Sep-25-1990 |
Disclosed is a secret speech equipment for ensuring the secrecy of an analog voice signal, and used in voice communication systems such as an analog telephone and mobile radio. The equipment comprises... |
| 4953211 |
Encryption apparatus |
| Aug-28-1990 |
Encryption apparatus mainly intended for encrypting speech signals samples a signal to be encrypted at two differing rates, and reads the sampled signal into storage means at one of said rates and reads... |
| 4932057 |
Parallel transmission to mask data radiation |
| Jun-5-1990 |
Aircraft often include a central memory which distributes data to a number of communication, navigational and other utilization devices. In order to achieve a high degree of security for data transmission... |
| 4926478 |
Method and apparatus for continuously acknowledged link encrypting |
| May-15-1990 |
An authentication system in which communication between two locations is provided by a continuous full duplex bidirectional communications highway, which highway is a secure link between the two locations.... |
| 4920567 |
Secure telephone terminal |
| Apr-24-1990 |
A secure Telephone Terminal apparatus and method is disclosed which permits clear analog or coded digital message signals to operate on a non-secure telephone network having conventional equipment. This... |
| 4920565 |
Method for connection of secure conference calls |
| Apr-24-1990 |
The present invention provides a method and apparatus of making secure conference calls in which the bridging unit does not need to know any encryption keys and can function independently of the encryption... |
| 4907275 |
Encryption apparatus |
| Mar-6-1990 |
In an encryption apparatus, prior to encryption process, information indicating whether plain text blocks are to be encrypted or not is stored in a mask register, and the number of blocks of the plain... |
| 4852166 |
Analogue scrambling system with dynamic band permutation |
| Jul-25-1989 |
An analogue scrambling system with dynamic band permutation in which the speech signal is filtered (1), sampled (2) at the rate f.sub.e, digitized (3), transformed by means of an analysis filter bank (4)... |
| 4850019 |
Data randomization equipment |
| Jul-18-1989 |
Input data is split by a splitting part into a plurality of block data having an equal data length to be processed through respective channels. Each channel data is subjected in a function operation part... |
| 4847860 |
Phase-control system for telecommunications signals received by an adaptive antenna |
| Jul-11-1989 |
In a receiving station having an adaptive receiving antenna, a phasing system comprises a plurality of reception paths receiving telecommunications signals derived from the same useful signal combined... |
| 4811357 |
Secondary channel for digital modems using spread spectrum subliminal induced modulation |
| Mar-7-1989 |
A system and method are provided for use of a secondary channel in high speed (greater than 2400 bits per second) wire line modems to provide low speed (around 110 bits per second) non-interfering communications... |
| 4805216 |
Method and apparatus for continuously acknowledged link encrypting |
| Feb-14-1989 |
The method and apparatus of the invention described herein provide confidential communications between two or more stations whereby the exchanged messages themselves provide the necessary enciphering keys... |
| 4802220 |
Method and apparatus for multi-channel communication security |
| Jan-31-1989 |
A multi-channel communication security system where the information in an original information message is split among a number of channels in accordance with a message splitting routine such that the interception... |
| 4794643 |
Method for developing a key signal for descrambling in television broadcasting |
| Dec-27-1988 |
A scrambling method for TV pictures avoids deterioration of the reproduced picture by level compressing only selected horizontal flyback portions according to a randomly selected pattern to prevent synchronization... |
| 4567600 |
Method and apparatus for maintaining the privacy of digital messages conveyed by public transmission |
| Jan-28-1986 |
A private message of m bits is conveyed from its sender to its receiver by transmission of a public message of m bits, transmission of a public reply of m bits, and another transmission of a public message... |
| 4560832 |
Telephone system |
| Dec-24-1985 |
A cordless telephone system in which the incoming ring signals and audio signals transmitted from the base station to the remote station are digitized and encoded in accordance with a pseudo random code,... |
| 4555805 |
Secure mobile telephone system |
| Nov-26-1985 |
A communications system including a central station and a plurality of remote stations, for example, a mobile telephone system, is disclosed in which communications channel establishing signalling transmissions... |
| 4418425 |
Encryption using destination addresses in a TDMA satellite communications network |
| Nov-29-1983 |
An encryption system is disclosed which is based on channel destination addresses for a time division multiple access (TDMA) satellite communications network. A superframe initialization vector is transmitted... |
| 4396802 |
Aswixs remote speaker and handset set |
| Aug-2-1983 |
A remote speaker and handset unit is interfaced with a satellite communicons system and a number of common users. A vocoder is interposed between each unit and the communications system to enable a real-time... |
| 4392241 |
Digital interface system |
| Jul-5-1983 |
A system interfaces classified information for encryption and transmission over ultra high frequency (uhf) or high frequency (hf) bands and for receiving and decryption of uhf and hf information for relay... |
| 4387455 |
Apparatus and method for transmission of communications |
| Jun-7-1983 |
Apparatus for transmission of information in digital form comprising apparatus for providing a plurality of signals coded into a multiplicity of digital code elements in accordance with a first modulation... |
