Secure by Design for Developers

Purpose

Secure by design means engineers build security into the design, code, tests and deployment evidence from the start.

Developer Responsibilities

Developers are responsible for:

• understanding security requirements

• protecting secrets

• validating input

• enforcing authorization

• avoiding insecure APIs

• writing security-relevant tests

• logging safely

• reviewing dependencies

• responding to vulnerability findings

• recording security exceptions

Secure Coding Principles

• Deny by default.

• Least privilege.

• Validate at boundaries.

• Authorize every sensitive action.

• Keep secrets out of code.

• Use platform cryptography.

• Log events, not secrets.

• Fail safely.

• Keep dependencies current.

• Prefer supported frameworks over custom security code.

Security Requirements in User Stories

Security acceptance criteria should be included in work items.

Example:

Given a user without Cases.Read
When they request GET /v1/cases/{id}
Then the API returns 403
And no case data is returned
And the access denial is logged with correlation id

Secure Code Review Questions

• Is authorization enforced server-side?

• Are object-level permissions checked?

• Is input validated?

• Are secrets externalised?

• Are logs safe?

• Are errors safe for clients?

• Are dependencies approved?

• Are cryptographic operations platform-standard?

• Are security tests included?

Required Evidence

• threat model or risk notes for sensitive features

• security acceptance criteria

• authorization tests

• dependency scan results

• code review record

• exception records if needed