Chapter 10 — Cryptography and trust services: orientation
Lesson map
Lesson 10 published. Map, example, EX028.
flowchart TD
N0["Learning outcomes"]
N1["10.1 Trust services around the council"]
N2["10.2 Who trusts whom"]
N3["10.3 The council as a provider"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4
N4 --> EX["Worked example"]
EX --> Q["Exercise EX028"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["10.1 Trust services around the council"]
N2["10.2 Who trusts whom"]
N3["10.3 The council as a provider"]
N4["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> Q["EX028"]
[Learning outcomes]
|
v
[10.1 Trust services around the council]
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v
[10.2 Who trusts whom]
|
v
[10.3 The council as a provider]
|
v
[Synthesis]
|
v
[Worked example] --> [Exercise EX028]
Learning outcomes
You will (1) define the trust services a council relies on; (2) explain who trusts whom in each; (3) identify the council's roles as consumer and provider of trust.
10.1 Trust services around the council
Rosa lists the trust services Harbourview uses: a public certificate authority for its websites; an internal certificate authority for staff devices and internal services; a document-signing service for council decisions; a timestamping service that proves when documents were signed; and the payment provider's webhook signatures. Each is a service whose assertions others rely on. She notes that the council is both a consumer of trust, relying on the public authority, and a provider, since citizens and partners rely on its signed decisions.
10.2 Who trusts whom
For each service Rosa writes who trusts whom. Browsers trust the public authority, which vouches for the council's websites. Council servers trust the internal authority, which vouches for devices. Citizens and courts trust the council's signing certificate, which vouches for decisions. The council trusts the payment provider's webhook key, which vouches for payment notices. RFC 5280 explains how certificate chains express such delegations. Writing these relations makes clear that a failure at one link, such as a stolen signing key, harms all who rely on it.
10.3 The council as a provider
Because the council signs decisions that citizens and courts may rely on years later, it carries a provider's responsibilities: protecting the signing key, documenting how signatures are made, keeping evidence for long-term validation and revoking promptly if a key is compromised. Rosa compares this with its consumer role, where it mainly configures and monitors. The distinction helps her explain to managers why the document-signing service deserves stronger controls than an ordinary web certificate. Rosa realises that partners judge the council by these details, and a single expired certificate on a public form erodes trust that took years to build.
Worked example
Rosa lists five trust services, maps who trusts whom and explains why the council's signing role carries provider responsibilities.
Synthetic case. The council's services are invented; RFC 5280 is real.
Errors and limits
Trust relations change when suppliers change; review them. Providers of trust need evidence that lasts as long as reliance does.
Exercises
- EX028 — Five services. Name the five trust services the council uses. Rubric: 3 = public CA, internal CA, document signing, timestamping, payment webhook signatures;; 2 = four;; 1 = two;; 0 = none.
- EX029 — Webhook trust. Who trusts whom for payment notices? Rubric: 3 = the council trusts the payment provider's webhook key;; 2 = partly correct;; 1 = reversed;; 0 = none.
- EX030 — Provider duties. List three provider responsibilities for signed decisions. Rubric: 3 = three of protect key, document process, keep evidence for long-term validation, revoke promptly;; 2 = two;; 1 = one;; 0 = none.
Synthesis
Trust services define who relies on whom; the council's role as signer brings duties beyond those of a consumer.
Continue studying — chapter 10 of 30
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