The idea of generating random IPv6 addresses (so you cannot be tracked across multiple networks based on your MAC address) that stay stable within each subnet (so you don’t pollute everyone’s ND cache every time you open your iPad) is pretty old: RFC 7217 was published almost exactly four years ago.
Linux was quick to pick it up, OpenBSD got RFC 7127 support a few weeks ago. However, there’s an Easter egg in the OpenBSD patches that implement it: SLAAC on OpenBSD now works with any prefix length (not just /64).
Turns out there never was a requirement to have /64 prefixes to use SLAAC before RFC 4291 was published (RFC 4291 specifies the length of interface identifiers to be 64 bits)… or so Peter Hessler claimed during a Troopers dinner. Disagree? Please write a comment!
New to IPv6?
I decided I won’t spend any more time on a protocol that is old enough to buy its own beer, but the IPv6 webinars on ipSpace.net are still pretty relevant (yeah, nothing much has changed in the meantime).