Apparatus and method of generating random numbers

A method comprising:

• receiving, at first digital circuitry and second digital circuitry a random output from an entropy source, the second digital circuitry being a duplicate of the first digital circuitry;
• with the first digital circuitry:
• generating random numbers based on said output;
• and
• checking the entropy of said output,
• with the second digital circuitry:
• generating random numbers based on said output;
• and
• checking the entropy of said output, and
• determining a difference of operation between the first digital circuitry and the second digital circuitry.

An apparatus comprising:

• means for providing an entropy source, the entropy source being configured to provide a random output;
• first means for receiving the output of the entropy source and, based on said output, generate random numbers;
• second means for receiving the output of the entropy source and, based on said output, generate random numbers, the second means being a duplicate of the first means;
• and
• means for determining a difference of operation between the first digital means and the second means,
• wherein each of the first means and the second means comprises means for checking the entropy of the output of the entropy source.