Random number generating circuit, semiconductor integrated circuit, IC card and information terminal device

A semiconductor integrated circuit, comprising:

• a random number generating circuit that receives as an input a first digital random number signal generated at a first generating rate,
• wherein the random number generating circuit includes:
• a continuous signal processing unit to process the first digital random number signal so that any of its high and low levels do not repeat more than or equal to a predetermined number of times;
• a high-rate signal introducing unit to introduce a signal component corresponding to a second generating rate that is twice as high as the first generating rate into the first digital random number signal;
• a smoothing unit to control a frequency of occurrence for the high and low levels in a data sequence of the first digital random number signal;
• and
• an output to thereby output a second digital random number signal having the second generating rate, the second digital random number signal generated by outputs from the continuous signal processing unit, the high-rate signal introducing unit, and the smoothing unit,
• wherein the high-rate signal introducing unit introduces the signal component corresponding to the second generating rate by detecting a rising and falling edge of the levels in the first digital random number signal generated at the first generating rate by using a clock having a frequency that is twice as high as a frequency of a clock used to generate the first digital random number signal at the first generating rate.

An IC card, comprising:

• a semiconductor integrated circuit including a random number generating circuit that receives as an input a first digital random number signal generated at a first generating rate,
• wherein the random number generating circuit includes:
• a continuous signal processing unit to process the first digital random number signal so that any of its high and low levels do not repeat more than or equal to a predetermined number of times;
• a high-rate signal introducing unit to introduce a signal component corresponding to a second generating rate that is twice as high as the first generating rate into the first digital random number signal;
• a smoothing unit to control a frequency of occurrence for the high and low levels in a data sequence of the first digital random number signal;
• and
• an output to thereby output a second digital random number signal having the second generating rate, the second digital random number signal generated by outputs from the continuous signal processing unit, the high-rate signal introducing unit, and the smoothing unit,
• wherein the high-rate signal introducing unit introduces the signal component corresponding to the second generating rate by detecting a rising and falling edge of the levels in the first digital random number signal generated at the first generating rate by using a clock having a frequency that is twice as high as a frequency of a clock used to generate the first digital random number signal at the first generating rate.

An information terminal device, comprising:

• a semiconductor integrated circuit including a random number generating circuit that receives as an input a first digital random number signal generated at a first generating rate,
• wherein the random number generating circuit includes:
• a continuous signal processing unit to process the first digital random number signal so that any of its high and low levels do not repeat more than or equal to a predetermined number of times;
• a high-rate signal introducing unit to introduce a signal component corresponding to a second generating rate that is twice as high as the first generating rate into the first digital random number signal;
• a smoothing unit to control a frequency of occurrence for the high and low levels in a data sequence of the first digital random number signal;
• and
• an output to thereby output a second digital random number signal having the second generating rate, the second digital random number signal generated by outputs from the continuous signal processing unit, the high-rate signal introducing unit, and the smoothing unit,
• wherein the high-rate signal introducing unit introduces the signal component corresponding to the second generating rate by detecting a rising and falling edge of the levels in the first digital random number signal generated at the first generating rate by using a clock having a frequency that is twice as high as a frequency of a clock used to generate the first digital random number signal at the first generating rate.