Just a little rant here:
Increasingly, many schools are asking for letters of recommendation to be sent via PDF.
I sign my PDF letters using the PDF secure signature feature in Adobe Acrobat Pro. This embeds a digitally verifiable image and hash that links back through a public key system to me. It also locks and signs the PDF file so that it cannot be tampered with.
Adobe Acrobat Reader will automatically verify any embedded signatures that it finds in documents it opens, and let the reader know that the signature is bona fide.
I just found out that Preview.app in Snow Leopard (Mac OSX 10.6) doesn't either: 1) display, or 2) verify signatures. It just leaves a big blank where the sig should be.
Stupid, just plain stupid.
Continue reading Rant: Preview.app on OSX doesn't support PDF signature?.
