DigitalOcean doesn't offer SSL to buy. You can find a lot of providers outhere. I would recommend some from namecheap I think its called.

Thanks,
Diana

Check for SSL here: GoGetSSL

Try free Flexible SSL option from Cloudflare, is free and works awesome, also if you preffer buy one from SSLS (Namecheap SSL service) and change cloudflare from flexible SSL to Strict SSL for major plus service