When security is treated as a final review stage, many fixes become expensive because they are correcting architectural decisions that are already embedded. Secure-by-Design reverses that sequence by asking about assets, threats, and trust boundaries before requirements become code.
Turn security requirements into testable properties
“The system must be secure” is not executable. Requirements should become testable decisions: who may perform an action, where data originates, what must be logged, how failed validation behaves, and which component is authoritative for sensitive values.
The server is the trust boundary
The frontend can improve user experience, but it should not enforce core trust decisions. Authorization, prices, sensitive input validation, session state, and business-critical checks belong on the server or another trusted service boundary.
Auditability is part of the design
A useful audit trail is not simply a log file. It should support investigation, attribution, and review without unnecessarily exposing sensitive data, and should identify who performed an action, when it occurred, and the resulting state.