http://y7egb5vi45k74makeixpfb7jnimfxm3gf233lb3ke2ldonozjk55nvad.onion/how_to_generate_pgp_keys.html
It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy.
You may see the following message. If you do, follow the instructions and the key generation process will start automatically.