A UCSC engineer kept Apple's predictive text private

Second article down is the interesting one:

Has your iPhone begun to anticipate what you’re about to write with unnerving accuracy? Big data projects like text prediction often require processing extremely sensitive data. Keeping it secure is a top priority. UC Santa Cruz Computer Science and Engineering Associate Professor Abhradeep Guha Thakurta created a system for Apple called differential privacy which allows algorithms to learn from keyboard entries without disclosing it. The way this particular system works it is designed from the ground up for privacy. “Privacy is an English word,” Thakurta said. “To protect you must create a semantic statement that can be refuted, meaning a mathematical statement that tells what it means for a system to be protected, and that can be refuted, so to that end there’s this notion called differential privacy which one kind of formalized statement that gives it semantic meaning.” Differential privacy essentially allows a large, decentralized system to process confidential information in situ without any other part of the pipeline coming into contact with that information. So those confidential messages you’ve typed to your spouse or doctor never leave your device.