Formal Methods and CyberSecurity

Abstract: Formal methods have been largely thought of in the context of safety-critical systems, where they have achieved major acceptance. Tens of millions of people trust their lives every day to such systems, based on formal proofs rather than we haven't found a bug'' (yet!). Why iswe haven't found a bug'' an acceptable basis for systems trusted with hundreds of millions of people's personal data? This paper looks at some of the issues in CyberSecurity, and the extent to which formal methods, ranging from fully verified'' to better tool support, could help. Alas The Royal Society (2016) only recommended formal methods in the limited context ofsafety critical applications'': we suggest this is too limited.