They tend to generate electrical noise (often from a semiconductor), amplify that noise, sample it, de-skew the stream, and present that to a port for reading.<p>Here&#x27;s some information I had from a while ago. (Not all of this is about hardware RNGs) <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=6060636" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=6060636</a>