We have been working to make sure that everything is as secure as possible on the Haiku platform, and the good news is that we are doing well at it!
The development team have worked very hard to make this transition for your sites to HTTPS for all users smooth and unnoticeable - we think we succeeded!
You can see more information about this change on the release notes that can be found here.
Alongside this, the Oxford IT services security team have recently run a vulnerability scan across Haiku from the users and server perspective. We passed this with flying colours as well. They found no security issues with the Haiku set up, but did make an observation that we are already looking into.....forms, and making sure that it is not a robot submitting it! We have been working on putting a captcha in place, and will continue to do so. To date however, we have not had any reports of issues from users in this area. We will update you when this is being released.
We hope you enjoy being as secure as possible on Haiku!