Choose a key model from a stated requirement, five times

applied · 65 min · Objective 2.2

Task

Apply objective 2.2: take five requirements, each naming a different party that must be unable to decrypt, and select the key model that satisfies it -- with the cost you accepted stated alongside.

Steps

  1. Write lab/key-decisions.csv with header requirement,excluded_party,model,cost_accepted,precondition.
  2. Cover five distinct excluded parties: someone with the physical media, anyone outside the account, the database administrator, the platform operator, and a third party compelling the provider.
  3. For each, state the COST accepted -- lifecycle work, a new outage mode, an availability dependency, limited service support.
  4. For each, state the PRECONDITION that must hold for the model to deliver what it promises, and check it against your own lab.
  5. Find one place in your lab where the precondition does NOT hold -- a backup, an export or a lower-environment copy outside the key boundary -- and record it as a risk with an owner.

Verify

awk -F, 'NR>1 {n++} END {print n" decision(s)"}' lab/key-decisions.csv
awk -F, 'NR>1 {print $3}' lab/key-decisions.csv | sort -u | wc -l
awk -F, 'NR>1 && $4=="" {n++} END {print n+0" with no cost stated"}' lab/key-decisions.csv
awk -F, 'NR>1 {n++} END {print n" risk row(s)"}' lab/risk-register.csv

Five decisions, at least three DISTINCT models chosen, zero without a cost, and the risk register grown. If you chose the strongest model five times, re-read the lesson -- proportionality is part of correctness here.

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