After years of delay under government pressure, Apple said Wednesday that it will offer fully encrypted backups of photos, chat histories and most other sensitive user data in its cloud storage system worldwide, putting them out of reach of most hackers, spies and law enforcement.But most iPhone and Mac computer owners back up their iMessages, photos and other content to Apple’s iCloud, where the company can retrieve it for locked-out users or authorities.That has also left the material open to hackers that have tricked customers out of their passwords, increasing the potential for embarrassment and even extortion.Google offers encrypted backups, though it is unclear how popular the service is.Apple also said Wednesday that it was making iPhones compatible with physical security keys that would connect to the phone so that consumers can require them for access to their accounts from new devices."