Datotek, Inc.

Barrie O Morgan

Kenneth M Branscome

Frederick A Kinch, Jr

George E Goode

William M Feath

Merlon B Carter

Kenneth W Heizer

David W Abmayr

Mitchell M Wilkinson

The specification discloses a system and method for authenticating a message recipient prior to transmission of a message and for authenticating the message content after receipt of the message. A randomized character or character sequence is initially enciphered at the authenticator station and stored. The enciphered character is transmitted to the message recipient. The enciphered character is deciphered by the message recipient to reproduce the randomized character. The randomized character is reenciphered by the message recipient and transmitted back to the authenticator station. The reenciphered character is deciphered and the stored randomized character is compared with the deciphered character. The message recipient is authenticated if the stored randomized character exactly compares with the deciphered character. In order to authenticate the message after receipt, polynomial block check characters are accumulated from the message. The block check characters are enciphered according to a predetermined enciphering scheme and transmitted to a remote location, along with the message. The message is received at the remote location and polynomial block check characters are accumulated in response to the received message. Enciphered block check characters are received and deciphered according to the reverse of the predetermined enciphering scheme. The accumulated block check characters are compared with the deciphered block check characters and the message is authenticated if the compared characters are the same.

Recipient and message authentication method and system

A voice scrambler system (10) for encryption of a voice signal is provided. The voice scrambler system (10) includes a first generator (124) for generating a fixed frequency signal. A second generator (132) is provided for generating a plurality of frequency signals. Control circuitry (134) is provided for dynamically controlling the second generator (132) for randomly generating the plurality of variable frequency signals. A mixer (122) heterodynes the voice signal with the fixed frequency signal generated by the first generator (124). A filter (126) filters the output of the first mixer (122). An adder (128) adds the voice signal and the output of the first filter (126). A second mixer (130) heterodynes the output of the adder (128) with one of the plurality of frequency signals generated by the second generator (132). A second filter (136) filters the output of the second mixer (130) to generate an encrypted voice signal.

Dynamic frequency and time voice encryption system and method

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 of the device has a keyboard for the input of plain text or cipher text, including numeric characters and control signals and, further, has a display for displaying the inputs. Circuitry within the device is responsive to the inputs and controls the display. Additional circuitry enciphers or deciphers the inputs and substitutes the resulting text into the display. The device incorporates a random code generator for generating a randomized message key which, together with the keyboard inputs, initiates and generates a long sequence of randomized letters for enciphering purposes. In a deciphering mode, a predetermined message key may be entered to set the random code generator at a point to generate the originally entered plain text. Also, a basic key composed of multiple segments fully initializes the random code generator such that more than one device could be used to encipher and decipher text. Similarly, by using different segments of the basic key, varying levels of security can be obtained. Test circuitry is also provided to insure maintenance of the proper key variables and proper operation of the device.

Portable electronic cryptographic device

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 message tapes prior to transmission via teleprinter message circuits. The system may also be operated in an on-line asynchronous mode wherein a sending station may asynchronously transmit enciphered data on-line to a remote receiving unit, synchronization being provided by the start/stop pulses of the individual digital characters. The system may also be operated in an on-line synchronous mode wherein a sending and a receiving unit are automatically synchronized in time by local self-contained clocks in order to bridge fades or interference in a transmission medium such as radio telegraph, or the like. The system may be utilized on either half-duplex or full-duplex communication channels.

Multi-mode digital enciphering system

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

Multi-mode digital enciphering system with repeated priming sequences

Digital cryptographic system having synchronous and asynchronous

The specification discloses circuitry useful in a digital cryptographic system having a digital prime sequence which controls the generation of randomized key data. The circuitry includes a register for storing the digital prime sequence prior to generation of the randomized key data. A memory is provided which includes address inputs and data outputs and which stores predetermined digital relationships. A stage of the register is connected to an address input of the memory to select one of the stored digital relationships. A source of selectable digital bits is connected to another address input of the memory. The data outputs of the memory are operable to be coupled to the input of the register for generating an enciphered digital prime sequence. A clock clocks the contents of the register through the stages of the register in order to cause the enciphered digital prime sequence to be loaded into the register. The enciphered prime sequence is then utilized to control the generation of randomized data for use in the cryptographic system.

System for locally enciphering prime data

The specification discloses a random digital code generator operable over a series of key cycles for generating a randomized digital bit during each key cycle. The generator includes a plurality of first registers each having a predetermined cycle period which does not have a common factor with the cycle period of any other of the first registers. Circuitry is provided to step each of the first registers a predetermined number of steps per key cycle. A plurality of second registers are provided, along with circuitry for generating different numbers of clocking signals per key cycle for each of the second registers. Circuitry generates control pulses in response to the clocking signals and further in response to digital bits derived from selected taps on the first registers. The control pulses randomly control the number of times each of the second registers is stepped during each key cycle. The number of steps taken by each of the second registers does not have any common factor with the number of steps taken by any of the other second registers. Circuitry is responsive to the outputs of the second registers in order to generate a randomized digital bit during each key cycle. This circuitry includes two levels of multiplexing and further includes bit flipping and spoof circuitry to enhance the security and randomness of the generator.

Random digital code generator

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

Barrie O Morgan