Comment 4 for bug 323437

ok I guess this is an Ubuntu wide thing - there are other bugs #217138 and #404052 for ubuntu-meta. I did not realise that Ubuntu Live CDs are only for installing and exploration and not meant to be used for recovery, the alternative suggested (boot, get wifi/net working, enable Universe, apt update, apt install) is possible but somewhat cumbersome. Gentoo Live CD includes cryptsetup, (as does grml, Sidux, Finnix) so I was just used to having it right there.