Cryptography – Key management – Having particular key generator
Reexamination Certificate
1998-03-06
2001-03-13
Swann, Tod R. (Department: 2132)
Cryptography
Key management
Having particular key generator
C380S044000, C380S263000, C380S265000, C380S268000, C714S728000, C377S073000, C377S081000, C331S078000
Reexamination Certificate
active
06201870
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to communications systems and more specifically to pseudorandom sequence generators used in communications systems.
BACKGROUND OF THE INVENTION
Modem communications systems are highly interconnected with many different users executing different applications on different types of networks which are in communication. With the advanced technology, the transfer of large files rapidly over such systems is made possible using high-speed optical and electronic networks. When such files contain proprietary or personal information, there is an increased need to encrypt the data streams to ensure their integrity and security. Thus, as technology for 100 gigabit per second (Gbps) or above networks comes into widespread use, the demand for cost-effective, ultrafast data stream encryption generators becomes more urgent.
Typically, such encryption systems generate an encrypted data stream by modulating an input data stream with a pseudorandom sequence of bits. Unfortunately, at such high speeds, the generation of these pseudorandom sequences used to encrypt (or encode, if the generator is public) such data is typically extremely expensive and difficult with current high speed electronic encryption systems. Typically such systems operate with a throughput of less than 10 Gbps.
The present invention relates to a feedback shift register useful as a pseudorandom sequence generator for an encryption or encoding system capable of operating at these high data transmission rates.
SUMMARY OF THE INVENTION
In one embodiment the invention relates to a pseudorandom sequence generator including a first reconfigurable feedback shift register having at least one input and at least one output and a first controller having an output in communication with the at least one input of the first feedback shift register. The first feedback shift register operates at a first speed S
1
and the first controller operates at a second speed S
2
. In another embodiment the first speed S
1
of the first feedback shift register is an integer multiple of the second speed S
2
of the first controller.
In another embodiment the invention relates to a pseudorandom sequence generator in which a first reconfigurable feedback shift register includes a feedback shift register having an input, an output, and at least one tap, and a feedback function generator having a first input in communication with the at least one tap of the shift register, a second input in communication with the output of a first controller, and an output in communication with the input of the feedback shift register. The feedback function generator includes at least one feedback function. In another embodiment the feedback shift register has a length L, the first controller generates a first sequence having a period &tgr;, and the feedback shift register outputs a pseudorandom sequence at the output of the shift register. The pseudorandom sequence has a period substantially equal to &tgr;·(S
1
/S
2
)·(2
L
−1).
In yet another embodiment, the invention relates to a pseudorandom sequence generator in which a first controller further includes a second controller having an output, and a second feedback shift register having at least one input in communication with the output of the second controller and at least one output. The second feedback shift register operates at a third speed S
3
and the second controller operates at a fourth speed S
4
.
In another embodiment, the invention relates to a pseudorandom sequence generator which includes a non-linear feedforward function generator having an input in communication with at least one output of a first feedback shift register and an output.
In another embodiment the invention relates to a pseudorandom sequence generator which includes a first sequence generator, a second sequence generator and an interleaver. The first sequence generator has an output and includes a first feedback shift register having at least one input and at least one output and operating at a first speed S
1
, and a first controller having an output in communication with the at least one input of the first feedback shift register. The first controller operates at a second speed S
2
. The second sequence generator includes a second feedback shift register having at least one input and at least one output and a second controller having an output in communication with said at least one input of said second feedback shift register. The second feedback shift register operates at a third speed S
3
and the second controller operates at a fourth speed S
4
. The interleaver includes a first input in communication with the output of the first feedback shift register, a second input in communication with the output of said second feedback shift register, and an output.
In still yet another embodiment the invention relates to a communication system, including a first feedback shift register, a first controller, a modulator, a second feedback shift register, a second controller and a demodulator. The first feedback shift register has at least one input, and at least one output and operates at a first speed S
1
. The first controller has an output in communication with the at least one input of the first feedback shift register and operates at a second speed S
2
. The modulator has a first input in communication with the at least one output of the first feedback shift register, a second input for an input signal, and an output in communication with a communications link. The demodulator includes one input in communication with the communications link, an output for recovering the input data stream and a second input. The second feedback shift register has at least one input, and at least one output in communication with the second input of the demodulator. The second feedback shift register operates at the first speed S
1
. The second controller has an output in communication with the at least one input of the second feedback shift register and operates at the second speed S
2
.
In another embodiment the invention relates to a method of producing a pseudorandom sequence. The method includes the steps of providing a reconfigurable feedback shift register having at least one input and at least one output and a controller having an output in communication with the at least one input of the reconfigurable feedback shift register. The method also includes the steps of operating the controller at a first speed S
1
, operating the feedback shift register at a second speed S
2
and controlling the reconfigurable feedback shift register with the controller. In one embodiment the method includes the step of operating said feedback shift register at the second speed S
2
equal to &dgr; times the first speed S
1
of the controller; &dgr; being an integer greater than or equal to 2.
REFERENCES:
patent: 3681708 (1972-08-01), Olmstead
patent: 3751648 (1973-08-01), Wu
patent: 3761696 (1973-09-01), Russell
patent: 3777278 (1973-12-01), Majeau et al.
patent: 3946215 (1976-03-01), May
patent: 3947634 (1976-03-01), Betts
patent: 4202051 (1980-05-01), Davida et al.
patent: 4536881 (1985-08-01), Kasuya
patent: 4590601 (1986-05-01), Beeman
patent: 4734921 (1988-03-01), Glangano et al.
patent: 4905176 (1990-02-01), Schultz
patent: 5111416 (1992-05-01), Harada
patent: 5195136 (1993-03-01), Hardy et al.
patent: 5208705 (1993-05-01), Avramopoulos et al.
patent: 5235423 (1993-08-01), Dunbar et al.
patent: 5268949 (1993-12-01), Watanabe et al.
patent: 5446683 (1995-08-01), Mullen et al.
patent: 5506796 (1996-04-01), Ishida
patent: 5566099 (1996-10-01), Shimada
patent: 5608802 (1997-03-01), Alvarez
patent: 0 438 322 A2 (1991-07-01), None
patent: WO 88/04097 (1988-06-01), None
Brynielsson, Lennart, “On the linear complexity of combined shift register sequences”, Fst/TSA, Box 80001, S-10450, Stolkholm, Sweden, pp. 156-160, (1986).
Chan et al., “Reconfigurable feedback shift registers”, ISIT, 1997.
Gollmann, Dieter, “Pseudo Random Properties of Cascade Connections of Clock Controlled Shift Registers”, Lecture Notes in Compu
Chan Agnes H.
Hall Katherine L.
Medard Muriel
Moores John D.
Parikh Salil
Callahan Paul E.
Fish & Richardson P.C.
Massachusetts Institue of Technology
Swann Tod R.
LandOfFree
Pseudorandom noise sequence generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pseudorandom noise sequence generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pseudorandom noise sequence generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2465919