Yohann Signatys

Hello, I don't want to troll or whatever, just give a precise example. One month ago a colleague of mine had to digitally sign a pdf contract. Contract came back, the file was not valid, the document had been altered since the digital signature. Since our company actually deals with pdf signatures as their major activity, we tried to actively search for the cause, because no-one seems to have done something even related to edit the pdf. For instance, there is a button in Adobe products "activate modifications" or something like this, could have been this kind of mistake that my colleague did, and thus he would be the person to blame. But it was definitely not this, we hadn't a clue. It was only now, that is about one month later, that we understood the cause (and thanks to the blog post from Duff Johnson already linked in this discussion ) : My colleague just opened the document to view it, like "doubleclick on file, scroll down pages, nod, close" to make sure he was emailing the right one. That's all. That is, referring to what you said, yes, we used Apple Preview exactly as it's supposed to be, a *viewer*, not a PDF editor, not a paper shredder, not a movie maker, not a coffee machine. The mere action of opening it invalidated the signature, and that's certainly not something you're supposed to expect or even think to be careful about. Changing the default viewer to Acrobat Reader is of course, as you mentioned, the perfect answer, but : We'll have to warn and educate *all of our present and future colleagues and customers* to be very careful on this point. The mere fact we'll have to say : """ "Yes, nowadays you can forgot paper, you can store and securely sign PDF documents and store them as your old paper archive or use them as your old hand-signed old contracts sheets ! Ow, but if you have a Mac, don't look at them by just double-click the file or it will get trashed, without you even noticing it. you'll have to do a special manipulation before". """ doesn't seem very user-friendly to me. Of course in our case the solution was simple, we just did another document, signed it again and sent it and it was fine this time. But this could have disastrous consequences. But magine you're just looking at some old digitally signed archive. You use mac. You don't know anything about that Preview "undocumented feature". You just look at it. Poof. Your archive is now considered as altered documents, legally invalid, and maybe you can never produce the good signed document again. Maybe you have backup, but you won't think about restoring your file, because there doesn't seem to be any problem at this point. The time you realize the problem, backups may have been overwritten with a newer one. Just because you *looked at it with preview*. I think from now on I'm gonna call it "Gorgon", not "Preview". Yohann