Feature request: Support 'https' links

[saivinob]

Zsync files with 'https' are failing with error '...could not read control file from URL'. Changing the 'https' to 'http' fixes the issue i.e., we are able to download from the link address.

Currently affecting zsync downloads of Ubuntu isos (from cdimage.ubuntu.com). See bug report https://pad.lv/1927807.

Request to add 'https' support.

[em-winterschon]

Support for HTTPS should be a default option. How is zsync to be taken serious on the modern internet without support for TLS/SSL? This effectively makes zsync useless for most people.

[keithbowes]

Support for HTTPS should be a default option. How is zsync to be taken serious on the modern internet without support for TLS/SSL? This effectively makes zsync useless for most people.

zsync 0.6.2 was released in 2010. That was before the Snowden revelations in 2013 that made everyone move to HTTPS. I can only assume that the logic of the zsync developers at the time was that HTTPS was unneeded since it was only used for sites that required sensitive information, which wouldn't be necessary for synchronization. Surely, adding HTTPS support wouldn't be particularly difficult, but again, this project hasn't been updated in several years, so it doubtlessly wouldn't get merged upstream. Personally, the only use of zsync that I've ever seen has been for incremental updates for AppImages (but the tool that updates AppImages uses its own implementation, provisionally called zsync2, embedded into the tool).