1. A method of generating a number, the method comprising: asynchronously updating a plurality of linear feedback shift registers; wherein asynchronously updating the plurality of linear feedback shift registers includes: incrementing a plurality of counter values, each counter value associated with first and second associated linear feedback shift registers selected from the plurality of linear feedback shift registers; determining a plurality of update values, each update value comprising bit values selected from the first associated linear feedback shift register, each update value associated with a counter value of the plurality of counter values; comparing each update value with the associated counter value; and updating the second associated linear feedback shift register based on the comparing; selecting a mixing function using a balanced entropy value; and determining the number from bit values selected from the plurality of linear feedback shift registers based on the selected mixing function.