Datotek, Inc.

Kenneth M Branscome

Barrie O Morgan

George E Goode

William M Feath

Kenneth W Heizer

Merlon B Carter

The specification discloses a digital cryptographic system wherein each of the transmitting and receiving units includes a housing having a front panel. A push-button switch input array is mounted on the front panel, with each push-button switch corresponding to a different number to enable the manual inputting of code variables therethrough. A digital display is provided on the front panel to temporarily display each of the code variables input through the array. Storage circuits are provided to store the code variables input through the array. A switch is provided on the front panel to enable any one of the stored code variables to be selected. A random code generator is operable in response to the selected stored code variables in order to generate a sequence of randomized key digital bits. Circuitry is provided to encipher clear text digital data in a synchronous manner and to transmit enciphered data through a synchronous data link.

Digital cryptographic system and testing thereof

Digital cryptographic system having synchronous and asynchronous

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 system, a first scrambler is connected between the video amplifier and the transmitter modulator of the transmitting facsimile station. The first scrambler includes digital circuitry for digitizing the output of the video amplifier and enciphering circuitry for enciphering the digitized output of the video amplifier and for transmitting the enciphered output to the receiving facsimile station. A second scrambler is connected between the demodulator and the write amplifier of the receiving facsimile station. The second scrambler includes deciphering circuitry for deciphering the output of the demodulator and for applying the deciphered output to the write amplifier to provide a duplicate of the transmitted facsimile material. Initialization between the first and second scrambler is accomplished with the use of correlation and prime patterns. Circuitry is provided to maintain the first and second scramblers in synchronization with one another, and alarm systems are provided to indicate malfunction of the scramblers and to prevent the transmission of sensitive data in the unciphered state.

Synchronous digital data scrambling system

The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code generator generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utilized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of one of the frequency sub-bands. The rearranged and inverted frequency sub-bands are then transmitted over a conventional voice communication line to a similar voice scrambler unit which operates in synchronism to rearrange and invert the frequency sub-bands to the original state in order to render the voice signal intelligible. The system includes a unique synchronism technique which automatically compensates for time delays in transmission and which allows tolerance of transmission errors. The system includes an alarm function which becomes operative upon the occurrence of a malfunction and also includes various other safety devices to prevent the transmission of uncoded voice data in case of a malfunction of the system.

Voice security method and system

The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code generator generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utilized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of ones of the frequency sub-bands. The rearranged and inverted frequency sub-bands are then transmitted over a conventional voice communication line to a similar voice scrambler unit which operates in synchronism to rearrange and invert the frequency sub-bands to the original state in order to render the voice signal intelligible. The system includes a unique synchronism technique which automatically compensates for time delays in transmission and which allows tolerance of transmission errors. The system includes an alarm function which becomes operative upon the occurrence of a malfunction and also includes various other safety devices to prevent the transmission of uncoded voice data in case of a malfunction of the system.

The specification discloses a voice scrambler technique wherein a voice signal is split into a plurality of discrete frequency sub-bands. A random code genertor generates a randomized sequence of digital signals. A preselected first portion of each of the digital signals is utiized to control the rearrangement of the order of the frequency sub-bands according to a limited subset of all possible combinations of rearrangements of the frequency sub-bands. The limited subset is chosen to include only the most unintelligible of the possible combinations of rearrangements of the frequency sub-bands. A preselected second portion of each of the digital signals is utilized to control the random inversion of ones of the frequency sub-bands. The rearranged and inverted frequency sub-bands are then transmitted over a conventional voice communication line to a similar voice scrambler unit which operates in synchronism to rearrange and invert the frequency sub-bands to the original state in order to render the voice signal intelligible. The system includes a unique synchronism technique which automatically compensates for time delays in transmission and which allows tolerance of transmission errors, with the randomized signal generator being rapidly stepped prior to initial transmission to generate a prime word, the rapid advancement serving to compensate for transmission path delay.

Growing community of inventors

Dallas, TX, United States of America

Kenneth M Branscome