Abstract: A method and apparatus for use in encrypting and decrypting digital communications converting an initial block to final block based on freely selectable control information and secret key information having double the length of prior art keys and maintaining compatibility with the prior art encryption system.

Abstract: A method and apparatus for use in encrypting and decrypting digital communications converting an initial block to final block based on freely selectable control information and secret key information having double the length of prior art keys and maintaining compatibility with the prior art encryption system.

Abstract: A method and apparatus for use in encrypting and decrypting digital communications converting an initial block to final block based on freely selectable control information and secret key information having double the length of prior art keys and maintaining compatibility with the prior art encryption system.

Abstract: A random number source includes a ring oscillator generating an internal clock signal having random phase noise, and a first linear feedback shift register connected to the ring oscillator. A counter is connected to a first tap of the first linear feedback shift register for generating a count signal. A feedback bit controller is connected to a second tap of the first linear feedback shift register for generating a random feedback bit for a time based upon the count signal. A second linear feedback shift register is connected to the feedback bit controller for generating a random number based upon the random feedback bit.

Abstract: A block cipher device for a cryptographically secured digital communication system includes a pair of first stages connected in parallel for receiving an input data block and a control data block. Each first stage defines a respective first data path and includes a sum modulo-two unit for receiving the control data block and the input data block. Each first stage also includes a first nibble swap unit downstream from the sum modulo-two unit. A key scheduler generates a random key data block based upon a received key data block. A pair of second stages is connected in parallel downstream from the first stages and receives the random key data block, the control data block and output signals from the first stages for providing an output data block. Each second stage defines a respective second data path and includes a plurality of modulo units. The block cipher device further includes a bit diffuser connected in both of the first data paths for mixing data therebetween.

Abstract: A cryptographic device includes an input stage receiving an input data block and a key data block made up of a plurality of sub-key data blocks, and generating a plurality of first signals therefrom. An intermediate stage is connected to the input stage and includes a plurality of substitution units. Each substitution unit substitutes data within a respective first signal. A diffuser is connected to the plurality of substitution units for mixing data to generate a diffused signal. An output stage is connected to the intermediate stage for repetitively looping back the diffused signal to the input stage for combination with a next sub-key data block. The output stage provides an output signal for the cryptographic device after the repetitively looping back is complete.