ld be 8 bytes or longer in length; this RFC also recommends that
<em>iterations</em> be 1000 or greater.

<p>
Example:
<pre>
  # Tell mod_sql to use PBKDF2 passwords
  SQLAuthTypes pbkdf2
  ...

  # Use the SHA1 digest algorithm, 200K iterations, and expect an output
  # length of 20 bytes.
  SQLPasswordPBKDF2 sha1 200000 20

  SQLPasswordSaltFile /path/to/salt/file
</pre>

<p>
Use of <em>digest</em> algorithms other than SHA1 for
<code>SQLPasswordPBKDF2</code> requires OpenSSL-1.0.0c or later; earlier
vers