ND_add() before calling RAND_bytes().</p>

<h2 id="Entropy-Input-and-Additional-Data">Entropy Input and Additional Data</h2>

<p>The DRBG distinguishes two different types of random input: <i>entropy</i>, which comes from a trusted source, and <i>additional input</i>&#39;, which can optionally be added by the user and is considered untrusted. It is possible to add <i>additional input</i> not only during reseeding, but also for every generate request.</p>

<h2 id="Configuring-the-Random-Seed-Source">Configur