Read the spec file from the src.rpm file, some selected snippets from the extracted vsftpd-2.0.5-8.src.rpm spec file;
* Wed Nov 09 2005 Radek Vokal <email@example.com> 2.0.3-12
- rebuilt against new openssl
- close std file descriptors
So my guess is that it is built with ssl support.
And this supports my guess;