Pseudorandom number generator, stream encryption method, and stream encrypting communication method

• US 6,788,787 B1
• Filed: 02/24/2000
• Issued: 09/07/2004
• Est. Priority Date: 02/25/1999
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Ueno, Osamu, Ishihara, Tetsuya, Shono, Katsufusa
• Primary Examiner(s): Morse, Gregory
• Assistant Examiner(s): Lipman, Jacob
• Application Number:
  US09/512,284
• Time in Patent Office: 1,657 Days
• Field of Search: 708/250, 708/251, 380/46, 380/263
• US Class Current: 380/46
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 9/001 using chaotic signals
• CPC Class Codes: H04L 9/0668 producing a non-linear pseudorandom sequence
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

A chaos-generating loop includes a one dimensional mapping circuit (13) with non-linear input-output characteristics for generating chaos, a linear or non-linear AD converter (15) for converting an analog output of the one dimensional mapping circuit (13) to digital form, a sample-and-hold circuit (17) for holding and outputting the digitally converted value from the AD converter (15), in response to an external clock (C), and a linear or non-linear DA converter (19) for converting an output of the sample-and-hold circuit (17) to analog form and outputting this analog signal to the one dimensional mapping circuit (13), and a decoder for outputting a chaos stream in response to the output of the sample-and-hold circuit (17).

Claims

1. A pseudorandom number generator comprising:

a one dimensional mapping circuit for generating chaos having non-linear input-output characteristics;

an AD converter for converting an analog output of the one dimensional mapping circuit;

a sample-and-hold circuit for holding and outputting a digitally converted value from the AD converter in response to an external clock; and

a DA converter for outputting an analog converted value in response to the output of the sample-and-hold circuit as feedback to the one dimensional mapping circuit,

wherein quantizing divisions of at least one of the AD converter and the DA converter are made non-linear, and further wherein a binary stream is output responsive to the output of the sample-and-hold circuit.

2. A pseudorandom number generator according to claim 1, wherein quantizing divisions of the AD converter are linear and quantizing divisions of the DA converter are non-linear.

3. A pseudorandom number generator according to claim 1, wherein;

the one dimensional mapping circuit is implemented by a CMOS inverter,

the AD convener is configured so as to include an AD weighting resistive array and a comparator array that compares the relative size of an output obtained from a synthesized resistance of the AD weighting resistive array and the analog output from the one dimensional mapping circuit,

the sample-and-hold circuit is implemented as a flip-flop array that captures and holds the digital output of the AD converter in response to an external clock, and wherein

the DA converter is configured so as to include a DA weighting resistive array, and a switching array that outputs an output obtained from the synthesized resistance of the DA weighting resistive array in response to the digital output from the sample-and-hold circuit as feedback to the one dimensional mapping circuit.

4. A pseudorandom number generator according to claim 3, wherein an exclusive-OR array is inserted which takes the exclusive-OR of the outputs of each comparator making up the comparator array is provided between the AD converter and the sample-and-hold circuit.

8. A method for stream encryption, whereby a binary stream generated by a pseudorandom number generator according to claim 1 is used to perform stream encryption, thereby obtaining an encrypted text code, whereby the stream encryption is achieved by an exclusive-OR operation performed between a binary stream obtained from the pseudorandom number generator and the plain text to be encrypted.

9. A stream encrypted communications method that uses an encrypted text obtained by the stream encryption method according to claim 8.

5. A pseudorandom number generator comprising:

a chaos-generating loop comprising a pair of one dimensional mapping circuits for generating chaos having non-linear input-output characteristics, a pair of CMOS switches which alternately open and close an output side path of the one dimensional mapping circuits, in synchronization with an external clock, and a pair of feedback loops that cross-connect the analog outputs of each of the one dimensional mapping circuits, via the CMOS switches, as feedback to the inputs of the other of the one dimensional mapping circuits; and

a pair of AD converters that perform digital conversion of the analog outputs of the one dimensional mapping circuits that are extracted via the CMOS switches,

wherein in the chaos-generating loop, according to the elapse of the discrete time established by an external clock, the outputs of the one dimensional mapping circuits are alternately mapped, so as to output, via each of the AD converters, a binary sequence that is a chaos stream.

6. A pseudorandom number generator according to claim 5, further comprising:

a DA converter that performs an analog conversion of an initial value given in the form of a digital signal; and

a CMOS switch performing opening and closing of an output side path of the DA converter, synchronized to an external clock.

7. A pseudorandom number generator according to claim 5, wherein at least one of the pair of one dimensional mapping circuits has input-output characteristics that can be individually adjusted by means of an external adjustment voltage.

10. A method for stream encryption, whereby a binary stream generated by a pseudorandom number generator according to claim 5 is used to perform stream encryption, thereby obtaining an encrypted text code, whereby the stream encryption is achieved by an exclusive-OR operation performed between a binary stream obtained from the pseudorandom number generator and the plain text to be encrypted.

11. A stream encrypted communications method that uses an encrypted text obtained by the stream encryption method according to claim 10.