title: What characters are valid for an SSL certificate serial number?
body: <p>What characters are valid for an SSL certificate serial number?</p>
  <p>For example, I am sure <code>00</code> and <code>1000</code> are valid.</p>
  <p>But, I am not sure if <code>CCJRLR00</code>, <code>CCJRLI00</code>, <code>CCJRLS00</code> or <code>101010</code> are valid.<br>
  <sub>Why did I pick <code>CCJRL</code>? Because it is the short form of my profile name :) And <code>R</code> means <em>Root</em>, <code>I</code> means <em>Intermediate</em>, <code>S</code> means <em>SAN/Server</em> and <code>00</code> is the starting serial number for the first certificate that is issued.</sub></p>
  <p>So, I am wondering what characters are valid for SSL cert serial numbers.</p>
  <p>And what is the maximum serial number length? Is it 32 or 64? Without colon.</p>