Chapter 5 — Security literacy

Lesson map

Lesson 05 published. Map, example, EX013.

flowchart TD
  N0["Learning outcomes"]
  N1["5.1 Confidentiality, integrity and availability"]
  N2["5.2 Assets and threats"]
  N3["5.3 Basic controls"]
  N4["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4
  N4 --> EX["Worked example"]
  EX --> Q["Exercise EX013"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["5.1 Confidentiality, integrity and availability"]
  N2["5.2 Assets and threats"]
  N3["5.3 Basic controls"]
  N4["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX013"]

[Learning outcomes]
    |
    v
[5.1 Confidentiality, integrity and availability]
    |
    v
[5.2 Assets and threats]
    |
    v
[5.3 Basic controls]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX013]

Learning outcomes

You will (1) explain confidentiality, integrity and availability; (2) identify assets and threats; (3) describe basic controls.

5.1 Confidentiality, integrity and availability

Security is often summarised as protecting confidentiality, integrity and availability. For Lantern Hill, confidentiality means members' names and shift histories stay private; integrity means voucher balances are correct and cannot be changed without authority; availability means members can spend vouchers when the shop is open. Sofia notices that a blockchain mainly strengthens integrity, by making records hard to alter, while it can weaken confidentiality, because every node holds a copy of the records. This trade-off shapes the whole design. She decides early that names will never be stored on the ledger, only pseudonymous member codes.

5.2 Assets and threats

Sofia lists the cooperative's assets: the vouchers themselves, the private keys that control the treasury and minting, the member list, and the reputation of the cooperative. For each asset she asks who might harm it and how, in general terms. A lost key could stop minting; a stolen key could create vouchers without shifts; a careless export could leak the member list; a long outage could damage trust. She avoids technical attack detail and focuses on outcomes. The list becomes the starting point for every later chapter, and she updates it whenever the design changes or new risks become visible.

5.3 Basic controls

Controls reduce risk. Sofia groups them as preventive, which stop harm, detective, which notice it, and corrective, which recover from it. For the treasury, a multi-signature wallet requiring two of three keyholders is preventive. A daily comparison of vouchers issued with approved shifts is detective. A tested backup of keyholder recovery material is corrective. She learns that no single control is enough, because every control can fail. Layering them means one failure is caught by another. The cooperative already uses similar layers for its cash box: two people count the takings, and a bookkeeper checks them weekly.

Worked example

Sofia keeps names off the ledger, lists four assets and pairs the treasury with a 2-of-3 multisig, a daily shift comparison and tested recovery.

Synthetic case. The cooperative's assets and controls are synthetic.

Errors and limits

Assuming a blockchain improves every security property ignores its cost to confidentiality.

Exercises

• EX013 — Ledger trade-off. Which property does a shared ledger tend to weaken?
  Show marking criteria

  Rubric: 3 = confidentiality, because every node holds a copy;; 2 = confidentiality;; 1 = availability only;; 0 = none.
• EX014 — Asset list. Name one asset Sofia lists.
  Show marking criteria

  Rubric: 3 = treasury and minting keys;; 2 = member list;; 1 = the shop's furniture;; 0 = none.
• EX015 — Control types. Give one detective control.
  Show marking criteria

  Rubric: 3 = daily comparison of issued vouchers with approved shifts;; 2 = comparison;; 1 = multisig;; 0 = none.

Synthesis

The CIA properties, an asset list and layered controls form the base of security literacy.

Continue studying — chapter 05 of 40

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