“JTAG | IJTAG Semiconductor and Board Test Security” is an eBook that addresses weaknesses in the IEEE 1149.1 Boundary-Scan (JTAG) standard’s test access port found on printed circuit boards and chips. Describes general security strategies based on the IEEE 1687 Internal JTAG (IJTAG) standard that can overcome these problems. Is available free.
Asset InterTech, http://www.asset-intertech.com/Products/Boundary-Scan-Test/BST-Software/JTAG-IJTAG-Semiconductor-and-Board-Test-Security