David Litchfield (born 1975) is a British security expert and The Director of Information Security Assurance for Apple. Anne Saita, writing for Information Security magazine, called him along with his brother Mark Litchfield, "World's Best Bug Hunters" in December 2003. Computer security. Litchfield has found hundreds of vulnerabilities in many popular products, among which the most outstanding discoveries in products by Microsoft, Oracle and IBM.
https://en.wikipedia.org/wiki/David_Litchfield