Week 10 Bench: Scoring a leak

Attaching a number to how much a channel reveals, then using the numbers to build two rankings that disagree

26 April 2027

Before the Bench#

Read the week’s deck first: the six axes it introduces are the rubric this Bench applies, not a separate topic. Bring every prior Bench’s output — the keystroke waveform, the annotated power trace, the timing plot, the shielding costing, the cache hit/miss classification, the reflection notes, and week 8’s fitted decay constant. This session is the first that consumes all of them at once, and it is noticeably thinner without them.

In the Bench#

Three parts, in order.

Calibrate. Given a dataset pairing a secret value with many noisy measurements of it, estimate the mutual information, then recompute the estimate on the first 10, 100, 1,000 and all samples. Watch where it stops moving. An estimator run on too few samples reports a leak that is not there, which is the failure mode most likely to appear in your own capstone.

Place. Fill in the six-axis table for all seven channels. Four axes you can complete from your notes. Rate and volume you will have to estimate, and for most channels you will be estimating from a published figure rather than your own data — mark which is which on your table, because a taxonomy that hides the difference between a measurement and a citation is worth less than one that does not.

Rank, twice. Order the seven channels by what it costs an attacker to use each one, then order them again by what it costs a defender to close each one. The two orders will not match. Find the channel that moves furthest between them and be ready to defend your reasoning: that divergence is the entire point of building a taxonomy, and it is the move the capstone asks you to make on a device of your own.

Afterwards#

Keep the completed table and both orderings. The capstone asks for exactly this analysis narrowed to one device and one adversary, which will strike out most of the rows you just filled in — and knowing which rows a stated adversary strikes out is most of what week 12 teaches.