Apple says testing missed flaws in new encryption designed to protect against future attacks from quantum computers, so it turned to mathematical proofs to make sure the code works correctly before wider rollout. New research and source code published May 22 detail how Apple verified parts of its post-quantum cryptography stack. The research argues conventional software testing is good, but no longer provides sufficient guarantees for encryption systems used across more than 2.5 billion active devices. The effort centers on corecrypto, Apple's low-level cryptographic library used across iPhone , iPad, Mac , and other platforms. Future quantum computers could eventually break many of today's public-key encryption systems, hence the effort. Technology companies are racing to replace older encryption methods before practical attacks become possible. Apple built a custom formal verification system that checks its post-quantum implementations against official NIST specifications.…