I have some JPEG files uploaded by users. I need to be sure they are "clean". Sure, I can just recompress them to JPEG again and I will get "clean" files but either I will loose quality or files will be bigger.
So how can I repack JPEG files? I mean how can I loslessy copy "body" of the compressed JPEG but strip anything else (all comments, EXIF, zero bytes appended to files etc.)? I have seen some JPEG files with ZIP files appended to them. People use them to post as a JPEG but then they download, unpack the ZIP and have some special content hidden from site moderators. I want to avoid that too.