title: RSA_sign(), object(3) and NID_sha1
body: <p>The manpage for <a href="http://www.manpagez.com/man/3/RSA_sign/" rel="nofollow"><code>RSA_sign()</code></a> says about the <code>type</code> parameter:</p>
  
  <blockquote>
    <p><code>type</code> denotes the message digest algorithm that was used to generate <code>m</code>.
           It usually is one of <code>NID_sha1</code>, <code>NID_ripemd160</code> and <code>NID_md5</code>; see
           <em>objects(3)</em> for details.</p>
  </blockquote>
  
  <p>I included the headers as suggested, but my IDE claims there are no variables starting with <code>NID_</code> and I couldn't find the objects manpage anywhere on  the internet.</p>
  
  <p>What am I missing?</p>