Everything we have learned converges here. The CMOS gate from Chapter 0 is the reason power analysis works. The transistor switching of Chapter 1 is the physical mechanism the attacker reads. The cross-correlation of Chapter 3 is literally what differential power analysis computes. The finite state machines of Chapter 4 are the targets of clock glitching. The DRAM cells of Chapter 11 are the bits Rowhammer flips. The memory hierarchy of Chapter 14 is what Spectre and Meltdown exploit. The decapsulation chemistry of Chapter 16 is how attackers see PUF cells. The DSP filters of Chapter 17 are what align dirty traces. The bootloaders of Chapter 21 are where most fault attacks land. And the oscilloscope of Chapter 22 is the primary attack instrument. Hardware security is not a separate subject. It is what every chapter has been preparing you to break and to defend.
This is the capstone. We will not pretend to teach electronics anymore. The reader has the tools. We will use those tools to attack and to harden silicon, and we will dwell on the moments where the physics that makes a circuit work is the same physics that makes it leak.