| 4724541 |
Data-dependent binary encoder/decoder |
| Feb-9-1988 |
Apparatus for the secure transmission of digital data signals is disclosed in which fixed logic gates and a variable bank of logic gates are used in an encoding circuit to scramble the digital data signals... |
| 4710921 |
Digital signal transmitting system |
| Dec-1-1987 |
A digital signal transmitting system includes a digital signal generator, such as, an A/D (analog-to-digital) converter, for producing digital information signals representing music or data, and a control... |
| 4677434 |
Access control system for transmitting data from a central station to a plurality of receiving stations and method therefor |
| Jun-30-1987 |
An apparatus and a method of providing an access control for transmitted stock market data from a central radio station to a plurality of one-way radio receivers. Into each receiver is inputted an access... |
| 4669118 |
Self-synchronizing descrambler |
| May-26-1987 |
For the purpose of suppressing DC components and high energy components at different frequencies, digital signals are frequently transmitted in scrambled form. The realization of corresponding scramblers... |
| 4639548 |
Digital communication system including an error correcting encoder/decoder and a scrambler/descrambler |
| Jan-27-1987 |
An error correction code data communication system scrambles and descrambles both non-coded data and coded data by using substantially the same code process at the opposite ends of a transmission path.... |
| 4612414 |
Secure voice transmission |
| Sep-16-1986 |
Voice signals are transmitted over a voiceband telephone channel with a high degree of security and good voice quality by applying to the transmission channel a first signal which includes digital information... |
| 4608456 |
Digital audio scrambling system with error conditioning |
| Aug-26-1986 |
In the scrambling system, an analog audio signal is converted into a digital signal to provide a sequence of digital signal samples corresponding to the analog audio signal. Each digital signal sample... |
| 4608455 |
Processing of encrypted voice signals |
| Aug-26-1986 |
The occurrence of a transmission error which produces a multibit error burst in the decrypted version of a composite speech and synchronization encrypted signal using a one-bit cipher feedback or similar... |
| 4607375 |
Covert communication system |
| Aug-19-1986 |
The covert communication system comprises a first arrangement to translate binary "1" bits into different portions of a predetermined PN (pseudonoise) code sequence and primary "0" bits into a complement... |
| 4578703 |
Subscription television system |
| Mar-25-1986 |
A wireless subscription television system arranged to transmit ciphered video signals from a transmitter to receivers in which the transmitting system comprises an enable code setting means, a transmitting... |
| 4578532 |
Method and apparatus for code transmission |
| Mar-25-1986 |
A transmission code required for decoding an encoded transmission of messages between a transmitting station and a receiving station is first transmitted from one station to the other. Previously identified... |
| 4577059 |
Decoding process and apparatus |
| Mar-18-1986 |
A decoding system containing a synchronizing and entry detector rendering possible the phase-in of messages delayed, for example, by interference. In order to be able to decode parts of the message received... |
| 4563546 |
Method for preventing "compromising radiation" |
| Jan-7-1986 |
A method of preventing "compromising radiation" when processing and transmitting secret data information in data processing and long-distance data transmission systems. In addition to direct, physical... |
| 4555591 |
Integrated circuit devices for secure data encryption |
| Nov-26-1985 |
The present invention relates to apparatus for placing digital words or a private key into a register in an integrated circuit in such a manner that it cannot be later read or modified from outside the... |
| 4535355 |
Method and apparatus for scrambling and unscrambling data streams using encryption and decryption |
| Aug-13-1985 |
Methods and apparatus for scrambling and unscrambling a plurality of data streams having differing data, on a plurality of signal channels, are taught. The data streams may be television programs or other... |
| 4465153 |
Method of coding and decoding messages |
| Aug-14-1984 |
Method of coding and decoding messages wherein a basic key and a random message key, which is transmitted prior to the message, are used. Using a plurality of basic keys entails the problem that the proper... |
| 4440976 |
Automatic selection of decryption key for multiple-key encryption systems |
| Apr-3-1984 |
A receiver of digitally encoded voice signals that may be encrypted according to a plurality of keep subjects a received signal to decryption according to each of the keys. Decrypted signals are tested... |
| 4434322 |
Coded data transmission system |
| Feb-28-1984 |
A scrambler/encryption system for randomizing an information-containing data signal for transmission and for reproducing at the receiver the information-containing data signal. The information-containing... |
| 4399323 |
Fast real-time public key cryptography |
| Aug-16-1983 |
In a public key cryptographic system (FIG. 1) for communicating securely over an insecure communication channel (3), a sender (1, 2) enciphers a data message (D) using a public enciphering knapsack key... |
| 4393276 |
Fourier masking analog signal secure communication system |
| Jul-12-1983 |
The present invention relates to a secure communication system for analog signals which preserves the bandwidth of the original message signal by employing scrambling, or masking, techniques in the frequency... |
| 4390898 |
Scrambling and unscrambling video signals in a pay TV system |
| Jun-28-1983 |
A scrambler scrambles a video signal by replacing its vertical intervals with dummy video signal lines, and separately providing information relating to the timing of the replaced vertical intervals. This... |
| 4388643 |
Method of controlling scrambling and unscrambling in a pay TV system |
| Jun-14-1983 |
Scrambling of a video signal in a pay TV system is effected in dependence upon a first variable which is changed recurrently, e.g. monthly, and a second variable which changes from field to field. For... |
| 4370519 |
Autokey generator for secret communication system |
| Jan-25-1983 |
1. An autokey generator adapted for use in a secret communication system, comprising the combination of a source of binary digit pulse intelligence signals in digital mark-space from having a predetermined... |
| 4369333 |
Method and apparatus for enciphering and deciphering of information |
| Jan-18-1983 |
Plain text or information which is to be processed at the transmitter end of the system is formed by groups of plain text or information signals which are separated by separation signals. In the absence... |
| 4369332 |
Key variable generator for an encryption/decryption device |
| Jan-18-1983 |
An apparatus and method for generating a unique working key variable for controlling the operation of an encryption/decryption device during each user specified time period. The apparatus generates each... |
| 4350844 |
Encipering- and deciphering apparatus in the form of a typewriter |
| Sep-21-1982 |
An enciphering and deciphering apparatus in the form of a typewriter having an input device for the input of characters to be processed, a control device for the input of control commands determining the... |
| 4332977 |
Teletypewriter privacy system |
| Jun-1-1982 |
1. A teletypewriter privacy system comprising a first and a second pair of terminals responsive to printing-telegraphy signals having start bauds; means for generating program signals having a fixed timing... |
| 4316055 |
Stream/block cipher crytographic system |
| Feb-16-1982 |
The system disclosed comprises a dual function cryptographic system capable of operating in either a stream or block cipher mode. Further, with minimal alteration the system is capable of performing either... |
| 4302628 |
Analog signal encrypting and decrypting system |
| Nov-24-1981 |
An encrypting and decrypting system employing analog signals in which delay lines are employed in both the encrypter and decrypter so that the initial analog signal which is received may be switched by... |
| 4283602 |
Cryptographically secure communication system |
| Aug-11-1981 |
This relates to a cryptographically secure communication system employed with an analog input, an analog output and a transmission medium each having a given low frequency pass band with a predetermined... |
| 4266095 |
Binary code randomizing system |
| May-5-1981 |
1. In a secret communication system including a source of an intelligence signal wave, means for periodically sampling said signal wave at predetermined intervals, and means for developing from the samples... |
| 4255811 |
Key controlled block cipher cryptographic system |
| Mar-10-1981 |
A cryptographic system for encrypting a block of binary data under the control of a key consisting of a set of binary symbols. The cryptographic system may be utilized within a data processing environment... |
| 4229817 |
Portable electronic cryptographic device |
| Oct-21-1980 |
The specification discloses a portable cryptographic device, adapted to be hand-held through solid state electronics, which possesses the capability for enciphering and deciphering plain text. The housing... |
| 4185166 |
Multi-mode digital enciphering system |
| Jan-22-1980 |
The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered... |
| 4176246 |
Apparatus for the transmission end-enciphering and reception end-deciphering of information |
| Nov-27-1979 |
An apparatus for the transmission end-enciphering and reception end-deciphering of information comprising an enciphering device arranged at the transmitter for receiving plain text in the form of information... |
| 4172968 |
Electrical system |
| Oct-30-1979 |
1. In a secure communication system; means for producing an analog intelligence signal; means for limiting the amplitude of said signal; means for transforming portions of said amplitude limited signal... |
| 4172213 |
Byte stream selective encryption/decryption device |
| Oct-23-1979 |
An apparatus for insertion in a communications line for providing message secrecy within a significant portion of existing communications networks. At the transmitter end, the apparatus receives messages... |
| 4171513 |
Secure communications system |
| Oct-16-1979 |
A privacy communication system is herein disclosed comprising apparatus for digitizing information to be transmitted, apparatus for logically adding a selected pseudo-random digital code to the digitized... |
| 4168395 |
Start/stop teleprinter scrambler |
| Sep-18-1979 |
1. A start/stop cryptographic telegraphy terminal-equipment comprising electronic means for generating clock pulses, means responsive to the clock pulses for generating timing pulses occurring at a substantially... |
| 4166922 |
Multi-mode digital enciphering system with repeated priming sequences |
| Sep-4-1979 |
The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered... |
| 4126761 |
Method of and means for processing an audio frequency signal to conceal intelligility |
| Nov-21-1978 |
An input audio frequency analog signal, for example, speech, which is to be passed through a noisy transmission channel, is scrambled at the sending end by repetitively performing a modulo-v (MOD v) addition... |
| 4095046 |
Electronic enciphering- and deciphering apparatus in the form of a pocket calculator |
| Jun-13-1978 |
An electronic enciphering- and deciphering apparatus in the form of a pocket calculator, comprising an input device for the input of characters to be processed, a control device for the input of control... |
| 4091423 |
Synchronous digital data scrambling system |
| May-23-1978 |
The specification discloses a system for scrambling digital signals transmitted between a synchronous data transmitting station and a receiving station. When the scrambling system is used with a facsimile... |
| 4079188 |
Multi-mode digital enciphering system |
| Mar-14-1978 |
The specification discloses an electronic digital enciphering system which is selectively operable in a plurality of different modes. The system may be operated in an off-line mode for preparing enciphered... |
| 4071693 |
Method and apparatus for synchronizing a receiver end-key generator with a transmitter end-key generator |
| Jan-31-1978 |
A method of, and apparatus for, synchronizing a receiver end-Key Generator with a transmitter end-Key Generator wherein both Key Generators are coupled with a respective counter such that each counter... |
