Fairly enough, I was searching for clues about the file format and with the help of google translate some chinese forum, then i jump accross a github project with the source code for a decrypter along with the 16bit key. The source code was fairly simple so i made my own version of the decrypter just to try and it worked. Obviously won't release the key nor the github link as the decrypter could be used for unfair use, and that is why I asked the admin if it was fair to make a post with the tool given the fact that it could be useful to speedup the process of adding new media to the wiki.
But if it is considered a problem maybe i could just periodically release an archive with the new models and animations, I don't know.
By the way, because they are using a well known system for sprite animation (which is spine) i'm making a simple tool to load the spritesheets along with the json and atlas file to recreate and view the ships animation in a canvas and to extract png images from that.
Ah ok, honestly I don't know, the files are encrypted in AES with this 16 chars (i've said 16bit before, but a char is one byte as per standard of minimum 128bit key for AES) key, so being AES, there aren't many ways to obtain the key: brute-force, biclique or key-recovery, but it's very hard so is by far logical to think that the programmer already knew the key, maybe by social engineering.
BTW: I've finished the Animation viewer, so in the meantime, can I upload that one which is safe as it needs the already decrypted spritesheet (I've put the sample 00 ship as initial demo)?