These notes are intended primarily for students in my security seminar; a few of the references here are locally specific and may be confusing to others. Most of the content, however, is generic, and security researchers and practitioners, students of locksmithing, surreptitious entry specialists, and others with an interest in this subject may find it helpful, especially in conjunction with other resources. This page and all photos and other content here are protected under copyright, and unauthorized reproduction or use is prohibited. Contact me for permission. Matt Blaze University of Pennsylvania