I’m running Apache2+SSL inside a libvirtd (kvm) Virtual Machine.
After enabling SSL and trying to add another SSL site, apache should refuse to restart and the following error would show up in /var/log/apache2.log
Digest: generating secret for digest authentication
After doing some research, it turns out that the VM did not have enough entropy to generate much of anything. Increasing this is easy, but may not be completely secure.
# cat /proc/sys/kernel/random/entropy_avail
139
# apt-get install rng-tools
# rngd -r /dev/urandom -o /dev/random
# cat /proc/sys/kernel/random/entropy_avail
2220
After running rngd, the entropy will increase at a gradual rate.
If you want this to survive a reboot, you’ll need to put it in a startup script.