Enable hardware random number generator on Rarpberry PI 3b Plus (Centos 7)

• 1 yum install rng-tools
  vim /etc/default/rng-tools:
  HRNGDEVICE=/dev/hwrng
  
• 2 systemctl enable --now rng-tools && shutdown -r now
  
• 3 # Fix SE Linux permissions:
  journalctl -b | grep rng
  ausearch -c 'rngd' --raw | audit2allow -M my-rngd
  semodule -i my-rngd.pp
  
• 4 # Check Hardware RNG Device is enabled:
  sudo rngd -l
  
• 5 # Check it is working:
  sudo cat /proc/sys/kernel/random/entropy_avail
  sudo rngtest -c 1000 < /dev/hwrng
  
• N Check /usr/lib/systemd/system/rngd.service rngd -f ... Changed fill-watermark from 0 to 2048
  

References

• https://redhatlinux.guru/2016/04/03/increase-system-entropy-on-rhel-centos-6-and-7/
• https://www.sites.google.com/site/astudyofentropy/project-definition/raspberry-pi-internal-hardware-random-number-generator