This allows a website to ensure that cookies are set with the "secure" attribute (only used over HTTPS), and optionally only be allowed for the current host (set without a Domain attribute, and the path is set to "/"). This has been implemented in Chrome 49: https://googlechrome.github.io/samples/cookie-prefixes/ Explanation: https://chloe.re/2016/04/27/cookieprefixes/ Spec: https://tools.ietf.org/html/draft-west-cookie-prefixes-05
Cookies are implemented in underlying networking libraries, WebKit doesn't do this. Could you please file a bug at <https://bugreport.apple.com>?
This has been reported on <https://bugreport.apple.com>, under bug report 26837283.
<radar://problem/26837283>