Chapter 15 — Privacy and data protection: guided lab
Lesson map
Lesson 15 published. Map, example, EX043.
flowchart TD
N0["Learning outcomes"]
N1["15.1 Lab plan"]
N2["15.2 Results"]
N3["15.3 Fix"]
N4["15.4 Record"]
N5["Lab — CCTV footage past retention"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5
N5 --> EX["Worked example"]
EX --> Q["Exercise EX043"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["15.1 Lab plan"]
N2["15.2 Results"]
N3["15.3 Fix"]
N4["15.4 Record"]
N5["Lab — CCTV footage past retention"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> Q["EX043"]
[Learning outcomes]
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[15.1 Lab plan]
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[15.2 Results]
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[15.3 Fix]
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[15.4 Record]
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v
[Lab — CCTV footage past retention]
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[Worked example] --> [Exercise EX043]
Learning outcomes
You will (1) run a guided privacy lab safely; (2) verify retention on CCTV; (3) record results.
15.1 Lab plan
Aisha plans a guided lab on CCTV retention at one club using a synthetic index of clips. Quayside's policy keeps footage for thirty days unless flagged for an incident. EDPB Guidelines 3/2019 on video devices discuss retention and transparency. The index lists each clip's camera, date and incident flag but no images, so the lab avoids viewing footage of real people. Aisha agrees the plan with the club manager and the data protection officer, sets a date for the check and writes down what result would show a problem: any unflagged clip older than thirty days.
15.2 Results
The lab checks 500 clips. 304 are older than thirty days; twelve are held for incidents; 292 should be deleted. The oldest unflagged clip is 75 days old. Automatic deletion is not working. The result surprises the club manager, who believed deletion was automatic. The incident-flagged clips are expected, since footage linked to incidents is kept until the incident is resolved. Unflagged clips should never exceed thirty days. The age of the oldest clip, seventy-five days, suggests deletion stopped about six weeks before the check. The firmware log confirms the date.
15.3 Fix
The club's recorder had automatic deletion switched off after a firmware update. Aisha switches it on and adds a monthly check. The firmware update reset several settings to factory defaults, including automatic deletion. Aisha asks the vendor whether updates at other clubs did the same, and the vendor confirms the problem across one model. She checks the other clubs with that model and finds two more with deletion switched off, which are fixed the same week. She then asks for vendor update notes in advance.
15.4 Record
She records the findings and fix. Mr. Reilly notes that guided labs show how a simple check can reveal a silent failure. The record includes the date, method, result, root cause, fix and follow-up checks. She also suggests that the vendor change its update process so that privacy settings survive updates. The monthly check is added to the club manager's routine, and the results feed the monitoring she will build later in the course for all forty clubs. This one club becomes the template for the rest.
Lab — CCTV footage past retention
# CCTV footage retention: clips older than 30 days must be deleted unless flagged for an incident.
import random
r = random.Random(8)
clips = [(r.randint(0, 75), r.random() < 0.04) for _ in range(500)]
over = [a for a, f in clips if a > 30 and not f]; held = [a for a, f in clips if a > 30 and f]
print(f"clips {len(clips)}; older than 30 days {len(over)+len(held)}; held for incidents {len(held)}; to delete {len(over)}")
print(f"oldest unflagged clip {max(over)} days")
Run with python3 lab_cctv.py. Verified output:
clips 500; older than 30 days 304; held for incidents 12; to delete 292
oldest unflagged clip 75 days
Worked example
Aisha finds 292 of 500 clips past thirty days (oldest 75 days), traces it to deletion disabled by a firmware update, re-enables it and adds a monthly check.
Synthetic case. Clips are synthetic; EDPB Guidelines 3/2019 are real.
Errors and limits
One club's result may not represent all forty.
Exercises
- EX043 — Clips to delete. How many clips should be deleted? Rubric: 3 = 292;; 2 = close;; 1 = wrong;; 0 = none.
- EX044 — Root cause. Why was footage not deleted? Rubric: 3 = a firmware update switched off automatic deletion;; 2 = mentions firmware;; 1 = vague;; 0 = none.
- EX045 — Ongoing check. What ongoing control did Aisha add? Rubric: 3 = a monthly retention check;; 2 = mentions monthly;; 1 = vague;; 0 = none.
Continue studying — lesson 15 (chapter 15 of 30)
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