This [0] seems to indicate that they do: > iCloud secures your information by encrypting it when it's in transit, storing it in iCloud in an encrypted format,

This [0] seems to indicate that they do: > iCloud secures your information by encrypting it when it's in transit, storing it in iCloud in an encrypted format, and using secure tokens for authentication. For certain sensitive information, Apple uses end-to-end encryption. This means that only you can access your information, and only on devices where you’re signed into iCloud. No one else, not even Apple, can access end-to-end encrypted information. [0] https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303