Authentication and Authorisation

Start with the Consequence

A founder is reviewing how the product will enforce rules and respond when a request does not go to plan.

The immediate question is authentication and authorisation. The technical label matters only because it changes a product decision, a responsibility, or the evidence required before launch.

Turn the Term into Evidence

Start with the product consequence, then choose the simplest technical treatment that protects it. A longer tool list is not a stronger plan.

For this decision, the useful standard is that important rules hold for valid, invalid, repeated, and unauthorised requests.

• Make the decision explicit: Design and test identity and permissions as separate controls for every protected operation.
• Ask what evidence would show that the chosen approach works.
• Name the person or provider responsible when the approach fails.
• Record the result in the backend proposal and operational acceptance criteria.

Match the Control to the Consequence

Design and test identity and permissions as separate controls for every protected operation.

The principal risk is that a signed-in user can read or change another user's information. This does not require the most expensive possible solution. It requires the consequence to be understood and the control to match it.

1. Describe the user or business outcome that must be protected.
2. Identify the most credible failure and its consequence.
3. Compare the simplest adequate approach with one realistic alternative.
4. Set a review point for when the decision may need to change.

Evidence Compared with Assumption

Warning Signs

• Nobody can explain how authentication and authorisation changes a user or business outcome.
• The proposal does not address this risk: a signed-in user can read or change another user's information.
• The only evidence is a successful demonstration of the easiest path.
• The decision has no named owner, boundary, or review point.
• A provider-specific feature is being mistaken for a permanent product requirement.

Questions to Ask a Consultant

• What decision are we making about authentication and authorisation?
• Which user or business outcome does the recommendation protect?
• How have we reduced or accepted this risk: a signed-in user can read or change another user's information.
• What evidence can I review without relying on the original implementer?
• What is deliberately deferred, and when will it be reconsidered?
• Who owns the accounts, data, documentation, and recovery process?