“Only entropy comes easy.”

-Anton Chekhov.

We all want to be able to communicate with each other in total privacy. So we need lots of good random numbers to do that using cryptography. And true random numbers are the most secure. Following three golden rules, we’ll show how to make reliable entropy sources using commonly available components like Zener diodes and webcams. These can then be the foundations of your own true random number generators (TRNGs) you can rely on to not have been compromised by governments or their agencies. So why should you build a TRNG?

Zener diode circuit for generating entropy. Arduino board outline. A typical entropy output.