I'm trying to find out what algorithm and key strength is used by Windows (XP) Explorer in order to explain why it isn't secure, but it does not seem to be detailed anywhere (Google only seems to give me offers of other software, and MS KB search is about as useful as a chocolate fireguard).
I presume it uses the PKZIP stream cipher, which certainly has documented weaknesses, but I'd like to also note if the key strength is too small to prevent brute force.
.zipx
files either.