Abstract: 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 of permutation boxes with n inputs and n outputs and one from a plurality of substitution boxes with n inputs and n outputs, each of these boxes being under the control of a specific part of an m-bits key. In the product cipher circuit the data words are consecutively enciphered in whole and the enciphering device can be regarded as a delay line. The data words to be enciphered can be combined with coding words which depend on the specific sector of the computer storage, in particular a hard storage disk unit, where the data words are stored. The sector-specific coding words and/or the m-bits key can be combined with a key to be entered by a user.

Abstract: 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 of length 2.sup.N -1 chips. A sequence augmenting circuit is included which inserts at least one additional chip in the PN sequence at a predetermined position within the PN sequence so as to provide an output of an augmented PN sequence of length 2.sup.N chips. The generator may also include sequence shifting circuitry which is responsive to a mask input for providing a predetermined shift in the output augmented PN sequence without incurring a transition period where the shifted output is invalid.

Abstract: 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 a system controller and a scrambler for performing the scramble processing on the basis of the customer data sent from the organization center. In a normal state, the organization center communicates with one of the first and second control units and each of the first and second control units is operated in the same manner. In case of the occurrence of an abnormality or a fault in the communication control unit, only the other control unit is operated and the organization center communicates with the other control unit instead.

Abstract: 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, and which can be interconnected by at least one telecommunication network (1) having at least one switching exchange (10) for establishing at least one conference ring. Conference participating nodes are provided with completely identical designs so that each node (2,4,8) can perform all signal processing including amplification and speech-coding/decoding in a decentralized manner, while routing and switching of information takes place in the at least one network exchange (10). All the conference participating nodes (2,4,8) are connected in series in a conference ring, which only includes these conference participating nodes (2,4,8) for each new conference ring to be established.

Abstract: 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 complex function of frequency. The transformation is characterized in that the time duration of a transformed impulse signal is substantially increased. Decryption requires transformation of the encrypted signal by substantially the complex inverse of the encryption function. The transformations may vary in time during encryption/decryption of a signal.

Abstract: 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, such as duration and inter-transmission delay, are derived from the same source.

Abstract: 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 of operation are both resident in a single microcontroller which runs the nonsecure operations until a requirement for the secure operation is requested during call placement. The nonsecure mode is disabled during the period of time the secure mode is operational and is reenabled upon completion of the secure mode operation. The secure mode cannot be accessed externally to the microcontroller.

Abstract: 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 scrambling noise to the information signal, whereby the information signal is totally unintelligible by an interceptor. At a receiving station, a noise-cancelling signal is generated by an adaptive transversal filter and supplied to a subtractor where it is combined with the scrambled signal to recover the information signal. For generating the noise-cancelling signal, a descrambling noise identical to the scrambling noise is generated. The filter has a tapped-delay line for receiving the descrambling noise and a plurality of variable tap weights connected respectively to taps of the tapped-delay line.

Abstract: 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 geographic location. Messages transmitted from an allowable ground site having a proper location are received and processed. Messages from improper geographic ground stations are discarded by the system. The messages include over-the-air rekeying information. The secure satellite over-the-air rekeying method includes ground station transmissions to the satellite to be rekeyed. The satellite receives these transmissions from the ground station system. The satellite determines whether the geometric position of the ground station corresponds to a predetermined allowable position. If the position is an allowable one, the satellite system processes the received information and rekeys the satellite.

Abstract: 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 does not require a scrambler/descrambler at each called party location. The apparatus includes a base module having a call diverter connected to the public switched telephone network through two standard telephone lines. A bypass interface circuit is connected to the call diverter between the connections to the two telephone lines to selectively connect a scrambler/descrambler in series with the two telephone lines.In operation, a mobile telephone, such as a cellular telephone, places a call to the telephone number of the first telephone line to cause the call diverter to place the second line off-hook and supply a dial tone from the second line through the call diverter and the first line back to the cellular telephone.

Abstract: 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 it out of said storage at the other of said rates so that the signal is alternately dispersed upwardly and downwardly with each pair of upward and downward dispersion representing a frame. To improve security the apparatus further generates a pseudo random binary number, defines a superframe structure consisting of a predetermined number of said frames, and sets the starting point of each individual superframe as an upward or a downward dispersion in dependence on the next digit of said pseudo-random binary number.

Abstract: 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 from the memory to the utilization devices, data subsets are distributed to the utilization devices in parallel so that any radiation generated from the parallel branches results in superposition of individual data signals. In effect, a jumbled resultant signal is produced which is difficult or near impossible for unfriendly surveillance equipment to decipher.

Abstract: 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. Each location transmits information to the opposite location on a bit-by-bit basis, with a previously transmitted bit of information serving as a decoding key for the most recently received bit of information and said received bit in turn serving as the encoding key for the next bit to be transmitted. An authenticated transaction record is provided upon receipt of verified transactional data, and the reception of remotely received information may be authenticated to the sender of such data.

Abstract: 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 Telephone Terminal is utilized as a Remote Interface at the location of each predetermined telephone subscriber authorized to receive and transmit coded message signals. Included within the Telephone Terminal is a telephone line interface, a telephone interface, a signal converting stage, and a mode selector, or controller. By utilizing a duplexer in the telephone interface and telephone line interface, the controller utilizes separate inbound and outbound signal paths to determine if a coded message signal is about to be received and switches the mode accordingly. This permits either subscriber to select the coded mode regardless of which subscriber initially set up the call.

Abstract: 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 process used by the communicating parties. This means that there is no security requirement for the conference unit, there are fewer restrictions on where it can be placed, and it does not introduce any additional weaknesses in the security system.

Abstract: 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 text block sequence is stored in a count register. In the encryption process, the count register is sequentially decremented, and only the plain text blocks to be encrypted are read from an input buffer in an ascending order of addresses based on the information stored in the mask register. They are encrypted by an encryption circuit and the encrypted text blocks are stored in an output buffer at the corresponding addresses to the input buffer addresses at which the plain text blocks have been stored.

Abstract: 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) into N sub-band signals sampled at f.sub.e /N and transferred in a permuted order to a synthesis filter bank (13) accomplishing the calculations of the scrambled signal sampled at the rate f.sub.e. A set of permutations is protected in a memory (8) and a scrambling with dynamic permutation in time is obtained by changing the read addresses of the memory. The scrambled signal reconverted into an analogue signal (14, 15) is transmitted through an analogue channel to an unscrambler where it is preprocessed so that the synchronizing and equalizing functions are accomplished and where the accomplished processes are identical with those accomplished in the scrambler, the difference being that the permuted order of the N sub-band signals is restored.

Abstract: 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 to a function operation in direct or indirect relation to all the other channel data to produce new channel data. Each channel data is subjected in a transform operation part to a transform operation to produce new channel data. All final channel data obtained after function and transform operations are combined by a combining part to obtain randomized data.

Abstract: 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 in transmission with a disturbing signal having a frequency band outside the frequency band of the useful signal, via a plurality of primary sources of the receiving antenna. The phasing system includes a narrowband filtering circuit for filtering the overall telecommunications signal in one of the reception paths to derive a reference signal undisturbed by the disturbing signal and solely dependent on the useful signal. In phasing circuits respectively assigned to the reception paths, the useful signal alone is set to a phase as close as possible to the phase of the reference signal in order to obtain, after signal summing at outputs of the phasing circuits, a maximum power using signal mixed with an attenuated scrambling signal.

Abstract: 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 for control or monitoring functions. The secondary channel is used to monitor, configure and test the modems in the network using commands sent over the secondary channel. Secondary channels are also used in low duty cycle applications such as in alarms or teletype data transmission. The invention provides a spread spectrum secondary channel which occupies the same bandwidth as the primary data channel and is immune to jamming tones that would interfere with conventional frequency shift keying secondary channels. The spectrum spreading is achieved through use of the primary channel's trellis encoder. Phase shifts of 0.degree., 90.degree., 180.degree. or 270.degree. are induced depending upon the trellis state.

Abstract: 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 for the messages to be encrypted and transmitted from each respective station. A full duplex communications loop is utilized between stations and the messages are exchanged substantially simultaneously.

Abstract: 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 and analysis of any single channel does not compromise the privacy of the communication. The system provides secure communication terminal adapters in cojunction with user terminals for splitting and recombining of private communications together with control facilities in an integrated services digital network (ISDN) for selecting amoung a multiplicity of possible of message splitting routines and generating security code signals for transmission in separate D-channels to the user equipment.

Abstract: 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 at the receiver. Key signals are added repetitively to a plurality of horizontal synch signals in one frame so as to enable descrambling of the picture at the decoder, even if noise or data error interferes with one or more of the signals.