title: Openssl digest with hexadecimal coded input
body: <p>Does anyone knows how the <em>dgst</em> function of the Openssl library manage the input value? I mean, it considers the input value as ASCII characters or in any other charset encoding?<br>
  I'm trying to input hexadecimal values but can't find how to do this:</p>
  
  <pre><code>$echo -n "FFFF" | openssl dgst -sha256
  </code></pre>
  
  <p>The result is different from the obtained by other ways (e.g. Java's <em>MessageDigest</em>) with the hexadecimal number '0xFFFF' as input.  </p>