title: How long does it take to generate large prime numbers?
body: <p>Using a C implementation of bigint without any assembly, SSE etc.
  running on a 2ghz dual core pentium laptop; what is
  the average time that one should expect a prime number to
  be created in?</p>
  <p>Is it normal for primes which are greater than 512 bits to
  take 30 seconds?</p>
  <p>What about 2048, 4096 bits etc.?</p>
  <p>From security stackexchange <a href="https://security.stackexchange.com/q/56214/5121">question 56214</a></p>
  <blockquote>
  <p>I recently generated some custom Diffie-Hellman parameters which are basically just long (in the below case 4096 bit) primes.<br />
  As the generation took roughly 2 hours it cannot be something that is &gt;generated on the fly........</p>
  </blockquote>
  <p>Is this typical ? - 2 hours to generate a 4096 bit key ...</p>