US 2001/0033663 A1 · Pseudorandom number generation circuit and data communication system employing the same

Abstract

A pseudorandom number generation circuit 2 whose generation timings of pseudorandom numbers vary randomly is disclosed. The pseudorandom number generation circuit 2 includes a clock generation circuit 4 which generates four kinds of clocks, a selection signal generation circuit 8 which generates selection signals randomly, a selection circuit 6 which selects either one of the four kinds of clocks based on the selection signals, and a linear feedback shift register (LFSR) 10 which carries out shift operation based on the clock selected by the selection circuit 6. The LFSR 10 generates a pseudorandom number in response to the selected clocks. Since the selection of the clock is carried out randomly by the selection signal generation circuit 8, the generation timings of the pseudorandom numbers generated by the LFSR 10 are also random.

Claims9

Dependent claims

A pseudorandom number generation circuit comprising:

a selection signal generation circuit which generates a selection signal;
a clock generation circuit generates a plurality of clock signals having different frequencies each other;
a selection circuit which selects one of said clock signals in response to said selection signal;
a first shift register circuit including a plurality of first register circuits connected in series which carries out shift operation in response to said selected clock signal selected by said selection circuit;
a first gate circuit receiving output signals of two of said plurality of first register circuits;
means for supplying an output signal of said first gate circuit to a first stage of said first shift register circuit;
and
means for extract contents of at least a part of said first register circuits.

5 more elements

A data communication system comprising a first and a second cipher keys generation circuits which generate a first and a second cipher keys, respectively, an enciphering circuit which enciphers original data to enciphered data based on said first cipher key, and a deciphering circuit which deciphers said enciphered data to deciphered data based on said second cipher key,

said first cipher key generation circuit including a first pseudorandom number generation circuit generating a first pseudorandom number, a first clock generator generating a first clock signal based on said first pseudorandom number, a second pseudorandom number generation circuit generating a second pseudorandom number in response to said first clock signal, and means for supplying said second pseudorandom number to said enciphering circuit as said first cipher key,
said second cipher key generation circuit including a third pseudorandom number generation circuit generating a third pseudorandom number, a second clock generator generating a second clock signal based on said third pseudorandom number, a fourth pseudorandom number generation circuit generating a fourth pseudorandom number in response to said second clock signal, and means for supplying said fourth pseudorandom number to said deciphering circuit as said second cipher key.

Dependencies are inferred from the claim text.

Pseudorandom number generation circuit and data communication system employing the same

Life of this patent

Pseudorandom number generation circuit and data communication system employing the same

Life of this patent

Abstract

Claims9