Hi, as you wrote [1], debootstrap targetting a debian port fails because of an expired key in the stable release. This looks like bug #700841.
You need the debian-ports-archive-keyring package from unstable or stretch (even if you are using debian 7 or 8). Or you may add the current key from the web page https://www.ports.debian.org/archive Debian ports generates a new key in the beginning of the year. Only at release time does the debian-ports-archive-keyring package enter the stable distribution, possibly containing already expired keys. Regards, JH Chatenet [1] https://lists.debian.org/debian-powerpc/2016/10/msg00015.html
