They did about two years ago. <a href="http:&#x2F;&#x2F;images.apple.com&#x2F;iphone&#x2F;business&#x2F;docs&#x2F;iOS_Security_Feb14.pdf" rel="nofollow">http:&#x2F;&#x2F;images.apple.com&#x2F;iphone&#x2F;business&#x2F;docs&#x2F;iOS_Security_Fe...</a> (emphasis added):<p>&quot;Each file is broken into chunks and encrypted by iCloud using AES-128 and a key derived from each chunk’s contents that utilizes SHA-256. The keys, and the file’s metadata, are stored by Apple in the user’s iCloud account. <i>The encrypted chunks of the file are stored, without any user-identifying information, using third-party storage services, such as Amazon S3 and Windows Azure.</i>&quot;