Apple states all data is stored encrypted on disk except notes and e-mails. The allowance for e-mail may be because of performance reasons, such as supporting features including searching messages on the server or partly downloading messages and attachments.
Notes also aren’t encrypted on iCloud servers. The reason is that iCloud presently syncs notes utilizing IMAP and a result of this technique is that your notes are synced on Mac OS X through mail. Nonetheless, OS X 10.8 will have an accurate Notes app when it’s launched, so it’s possible that future Notes will utilize iCloud’s document store APIs and these notes will be encrypted on disk like the rest of iCloud data.
What Apple won’t talk about: The methods used to encrypt data on disk. It claims to use industry standard procedure to guarantee user data is stored safely. Let’s make some educated guesses.
Now we can go back to the matter at hand, is Apple’s iCloud safe and secure for you to use.
Since we are talking about how electronic data travels, let’s have you keep an image in your mind to make it a little simpler to imagine. Let the picture be your house, your street, and then Apple’s HQ building in Cupertino.
There are really several buildings with switches and routers that you go through, but this picture will do. Additionally, each time you go down your street (linking to iCloud), you get to drive the Batmobile. The Batmobile, in this instance, is called a secure sockets layer (SSL), which is why the address in your browser starts with “https” (the “s” indicates that you’re driving the true Batmobile and not a ugly, old Saturn.