During the last years, I was searching over the internet for a free SSL certificate like OpenSSL or Self Signed, but most of the self-signed SSL certificates are not trusted by most of the browsers. Finally, I got a website that can help us to generate SSL for 3 months for free. After 3 months you have to renew it from the same website. The website URL is www.gethttpsforfree.com and they have a script to do the automatic renewal every 2 or 3 months. Really, I did not try the script but I installed one SSL on my own website https://wailshalabi.com and it passes the result with more than 95% overall security check over the website www.ssllabs.com.
I hope you can enjoy doing the same as me.