What Is CIDR

I have a ipv6/64 prefix at home (my country is near 100% ipv6, including mobile), I am seriously thinking to add code to my noscript/basic (x)html browsers in order to randomize an ipv6/128 address for each instance (may need policy and new kernel IP interface). Domestic routers can handle a good amount of ipv6/128 addresses on a ipv6/64 prefix. I could "randomize" "fixed" ipv6/128 as internet "phone" numbers I would give to my contacts.

BUT, it seems I cannot do the same with my mobile ipv6 internet as it seems I get a ipv6/128 from my mobile ISP (may be a trick of my modem though, dunno). I think even a ipv6/96 should be more than ok for mobile, then there is the question of international roaming of such ipv6/96 prefixes. Namely, still a lot of ipv6/128 per web instance, and a lot of "fixed" ipv6/128 for internet "phones" or "servers".