The &quot;don&#x27;t roll your own crypto&quot; mantra was created by the NSA to make people afraid to develop and deploy cryptography.  See here: <a href="http:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=fwcl17Q0bpk" rel="nofollow">http:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=fwcl17Q0bpk</a>