Patent ID: 8285767

Claim:
An apparatus for generating a random number, comprising: at least one generator circuit, each said at least one generator circuit being configured to provide a first operating mode and a second operating mode, in the first operating mode each said at least one generator circuit operating as an oscillator, and in the second operating mode each said at least one generator circuit operating as a state retention element; a control signal generator for generating a control signal for input to each said at least one generator circuit; each said at least one generator circuit being responsive to the input control signal being at a set level to operate in the first operating mode, and being responsive to the input control signal being at a clear level to operate in the second operating mode, on a transition of the input control signal from said set level to said clear level each said at least one generator circuit being configured to capture within the state retention element a current value of the oscillator, and to output that current value to form at least part of the random number.