For years, tech companies have struggled between two impulses: the need to encrypt users' data to protect their privacy and the need to detect the worst sorts of abuse on their platforms. Now Apple is debuting a new cryptographic system that seeks to thread that needle, detecting child abuse imagery stored on iCloud without--in theory–introducing new forms of privacy invasion. In doing so, it's also driven a wedge between privacy and cryptography experts who see its work as an innovative new solution and those who see it as a dangerous capitulation to government surveillance. Today Apple introduced a new set of technological measures in iMessage, iCloud, Siri, and search, all of which the company says are designed to prevent the abuse of children. A new opt-in setting in family iCloud accounts will use machine learning to detect nudity in images sent in iMessage.