An app note from Maxim Integrated about tampering electronic securities through physical means and how to protect against it. Link here (PDF)
More and more frequently, computer-based systems store valuable data and manage the flow of valuable commodities. If an opponent can gain control of the computer that touches this valuable data, they can access your private information, steal your money, or fraudulently access goods and services. In this article we look at tampering and what we can do about it.