But it is, in fact, quite simple: To encrypt notes, Evernote would only have to store the password (encrypted with a master-passphrase) for the note inside the note itself. That way, the notes can be synced exactly the way they are now. The master-passphrase would be something only the user knows and never leaves his/her device; either completely new or derived from the credentials already used for evernote (username/password). You could even use different master-passphrases per notebook, which would create the illusion of the notebooks being encrypted separately. I see no reason why this should not work cross-platform. As for sharing: for shared notebooks, the users would simply have to exchange the master-passphrase for that notebook once in person or otherwise securely. For shared notes you could do the same, or you could use public-key-encryption for the note-password: encrypt it using the other person's public key and only they can decrypt it and afterwards decrypt the note. All this could even be automated and implemented completely transparent to the user. Which is why I for one can absolutely not understand why this has not yet been done. The lack of useful encryption is what is keeping me from actually using evernote on a more permanent basis (also the unavailabitly of a linux client but thats a different matter...).