Unpredictable bit stream generator
First Claim
1. An apparatus for generating an unpredictable stream of digital data, said apparatus comprising:
- an oscillator including an odd-numbered plurality of digital logic inverter circuits coupled in series to form an endless ring, each of said inverter circuits having a propagation delay time, said oscillator providing an oscillating digital output signal having frequency determined by the number of inverter circuits and by said propagation delay time of said inverter circuits, said propagation delay times being affected by external influences on said inverter circuits;
a first sequence generator coupled to said oscillator for generating sequences of digital data, said sequences being corrupted by variations in said frequency of said oscillator output signal; and
altering means coupled to said oscillator for time-variably altering at least one of said external influences to thereby alter said frequency of said oscillator at times after completion of initial turn-on.
2 Assignments
0 Petitions
Accused Products
Abstract
An apparatus for breaking the periodicity of the pseudorandom bit stream output from a linear sequence generator. The apparatus includes a ring oscillator which periodically corrupts the sequence of the generator. The level of the supply voltage applied to the logic elements of the ring oscillator is varied over time, thereby altering the oscillator output frequency. In a second embodiment, the temperature of the logic elements of the ring oscillator is varied over time, thereby also altering the oscillator output frequency. A system comprising four of the above-disclosed apparatus having different linear sequences and different corrupting influences, are multiplexed, wherein the multiplexing selection criterion is determined by a logical combination of the four linear sequences.
39 Citations
21 Claims
-
1. An apparatus for generating an unpredictable stream of digital data, said apparatus comprising:
-
an oscillator including an odd-numbered plurality of digital logic inverter circuits coupled in series to form an endless ring, each of said inverter circuits having a propagation delay time, said oscillator providing an oscillating digital output signal having frequency determined by the number of inverter circuits and by said propagation delay time of said inverter circuits, said propagation delay times being affected by external influences on said inverter circuits; a first sequence generator coupled to said oscillator for generating sequences of digital data, said sequences being corrupted by variations in said frequency of said oscillator output signal; and altering means coupled to said oscillator for time-variably altering at least one of said external influences to thereby alter said frequency of said oscillator at times after completion of initial turn-on. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus for generating an unpredictable stream of digital data, said apparatus comprising:
-
an oscillator including an odd-numbered plurality of digital logic inverter circuits coupled in series to form an endless ring, each of said inverter circuits having a propagation delay time, said oscillator providing an oscillating digital output signal having frequency determined by the number of inverter circuits and by said propagation delay times of said inverter circuits, said propagation delay times being affected by external influences on said inverter circuits; source means for providing a clocking signal; reclocking means coupled to said oscillator and responsive to said clocking signal for providing samples of said oscillator output signal; a first sequence generator coupled to said reclocking means for generating sequences of digital data, said sequences being corrupted by variations in said samples of said oscillator output signal; and altering means coupled to said oscillator for time-variably altering at least one of said external influences for altering the frequency of said oscillator at times after completion of initial turn-on. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
-
13. A system for generating an unpredictable stream of digital data, said system comprising:
-
source means for providing a clocking signal; a plurality of apparatus for generating an unpredictable stream of digital data bits, each one of said apparatus comprising; (a) an oscillator including an odd-numbered plurality of digital logic inverter circuits coupled in series to form an endless ring, each of said inverter circuits having a propagation delay time, said oscillator providing an oscillating digital output signal having frequency determined by the number of inverter circuits and by said propagation delay times of said inverter circuits, said propa-gation delay times being affected by external influences on said inverter circuits; (b) reclocking means coupled to said oscillator and responsive to said clocking signal for providing reclocked samples of said oscillator signal; (c) a first sequence generator coupled to said reclocking means for generating sequences of digital data, said sequences being corrupted by variations in said reclocked samples of said oscillator signal; and (d) frequency altering means coupled to said oscillator for time-variably altering the frequency of said oscillator at a time after completion of initial turn-on; and said system further comprising a single combining means having a plurality of input terminals and an output terminal, said combining means being coupled at said input terminals to said respective plurality of first sequence generators, for providing at said output terminal a stream of digital data which is an unpredictable selection of one of said plurality of sequences of digital data generated by said plurality of first sequence generators. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
-
Specification