Security by Design and Privacy by Design start from a simple, powerful idea: security and privacy are not features you add at the end of the project, but properties you build from the very first requirement. Instead of "fixing it later," the organization shifts protection to the start of the software lifecycle — the movement the industry calls shift-left — reducing cost, risk and remediation time.
For decades, security and privacy were treated as inspection stages: the product was built and, only on the eve of launch, someone ran a penetration test or reviewed what personal data was being collected. The result was predictable — structural vulnerabilities that are expensive to fix, rework and regulatory exposure. Classic software engineering studies show that fixing a defect in production can cost orders of magnitude more than fixing it at the requirements stage. Security by Design and Privacy by Design reverse this logic.
The difference is not only one of timing, but of mindset. When security is a layer added at the end, it tends to be superficial: filters, validations and edge controls that mask symptoms without changing the cause. When it is designed from the outset, it shapes the data model itself, the contracts between services and the system's trust boundaries. A design flaw — such as implicitly trusting input from another microservice or storing sensitive data without need — is not solved with a patch; it requires rewriting the architecture. That is why the cost of remediation rises so steeply the later the problem is discovered.
What "from conception" means
Designing with security and privacy built in means that every architecture decision, data model and business flow already considers, by default, how to protect the system and the data subjects. This manifests across three complementary planes:
- Requirements: threats, legal obligations and privacy expectations are gathered alongside the functional requirements.
- Architecture: controls such as segregation, encryption and data minimization are design decisions, not later plugins.
- Operation: secure defaults, monitoring and response capability accompany the product in production.
The 7 foundational principles of Privacy by Design
Privacy by Design (PbD) was formalized in the 1990s by Dr. Ann Cavoukian, then Information and Privacy Commissioner of Ontario (Canada). Her framework of seven foundational principles became a worldwide reference and directly influenced Article 25 of the European GDPR (data protection by design and by default) and the spirit of Brazil's LGPD.
| # | Principle | What it requires in practice |
|---|---|---|
| 1 | Proactive not reactive; preventive not remedial | Anticipate and prevent privacy incidents before they occur, rather than remedying consummated harm. |
| 2 | Privacy as the default setting | The maximum level of protection must be the initial state, with no action required from the subject to be protected. |
| 3 | Privacy embedded into design | Protection is an integral part of the architecture and functionality, not an optional add-on. |
| 4 | Full functionality — positive-sum | Reject the false dilemma of "privacy or functionality"; seek mutual gain (win-win), not a trade-off. |
| 5 | End-to-end security | Protection throughout the entire data lifecycle, from collection to secure disposal. |
| 6 | Visibility and transparency | Operations and practices must be verifiable and open to audit by all stakeholders. |
| 7 | Respect for user privacy | Keep the subject at the center: clear consent, adequate notice and user-friendly options. |
Note that the fifth principle — end-to-end security — is exactly where Privacy by Design and Security by Design meet: there is no privacy without the information security that sustains it. An impeccable consent policy is worthless if the consented data leaks through a misconfigured storage bucket. The two concepts are two sides of the same coin: security protects information against improper access; privacy governs which information should even exist and for what purpose. Handling them in an integrated way from the design stage prevents decisions in one area from creating debt in the other.
A common misconception is to treat Privacy by Design as a legal checklist for the compliance team to fill in at the end of the project. Cavoukian makes it clear that it is a matter of engineering posture and organizational culture: the second principle, "privacy as the default setting," only makes sense if the product team makes concrete decisions — opt-in instead of opt-out, minimal retention by default, optional fields that are genuinely optional. These are design choices that precede any privacy policy text.
Security by Design in the SDLC
Security by Design (SbD) brings the same preventive philosophy to security engineering throughout the software development lifecycle (SDLC). Frameworks such as NIST SP 800-160 (Systems Security Engineering), ISO/IEC 27034 (application security) and OWASP SAMM (Software Assurance Maturity Model) describe how to embed security into each phase. The practical pillars are:
| Security by Design principle | Application |
|---|---|
| Threat modeling | Map assets, actors and attack vectors while still in the design phase (e.g., STRIDE) to prioritize controls. |
| Secure defaults | The default state is the most secure: mandatory TLS, MFA on, closed ports, minimal permissions. |
| Defense in depth | Multiple independent control layers, so that the failure of one does not compromise the system. |
| Least privilege | Each component, service and user receives only the strictly necessary access. |
| Fail-safe | In case of failure, the system assumes a safe state (deny by default), not a permissive one. |
These principles date back to Saltzer and Schroeder (1975), whose seminal paper on information protection in computer systems already listed economy of mechanism, fail-safe defaults, separation of privilege and complete mediation. Half a century later, they remain valid because they describe structural properties, not specific technologies. The gain of shift-left lies in verifying them continuously: design review, static and dynamic code analysis, dependency management and automated security testing in the pipeline.
Threat modeling deserves special attention because it is where theory becomes practice. Instead of asking "does this code have bugs?", threat modeling asks "who wants to attack this system, what would they gain and where would they get in?". Methodologies such as STRIDE — which classifies threats into spoofing, tampering, repudiation, information disclosure, denial of service and elevation of privilege — give a common vocabulary so that architects, developers and security reason together about the system's trust boundaries. Done early, it costs hours; discovered late, it costs an incident.
Privacy and security as a regulatory requirement
In Brazil, the General Data Protection Law (LGPD, Law 13.709/2018) transformed Privacy by Design and Security by Design from best practices into legal obligations. Two articles are especially relevant:
- Art. 46: requires processing agents to adopt security measures, technical and administrative, capable of protecting personal data from unauthorized access and from accidental or unlawful destruction, loss, alteration, communication or dissemination. §2 makes explicit that these measures must be observed from the design phase of the product or service through to its execution — that is, Privacy by Design written into law.
- Art. 49: establishes that the systems used to process personal data must be structured so as to meet the security requirements, the standards of best practice and governance, and the general principles set out in the law.
In Europe, Article 25 of the GDPR explicitly enshrines data protection by design and by default, requiring the controller to implement appropriate technical and organizational measures both at the time of determining the means of processing and during the processing itself. The convergence is clear: what was once Cavoukian's recommendation is today an auditable compliance requirement, with the potential for administrative sanction.
In regulatory practice, this means the organization must be able to demonstrate that it designed with privacy and security — the so-called accountability principle. Documents such as the RIPD, the records of processing operations, the retention policies and the threat-modeling artifacts stop being internal bureaucracy and become evidence of diligence before the ANPD or a European authority. Companies that treat these artifacts as a natural byproduct of development, rather than a standalone task, get through audits and client due diligence with far less friction.
Minimization, pseudonymization and DPIA/RIPD
Three practices make Privacy by Design concrete in the day-to-day of data engineering:
- Data minimization: collect only what is strictly necessary for the stated purpose, for the shortest possible time. Every form field and every database column must justify its existence.
- Pseudonymization and anonymization: replace direct identifiers with keys (pseudonymization — still personal data, but with reduced risk) or make re-identification unfeasible (anonymization — outside the scope of the LGPD). Techniques include tokenization, salted hashing and aggregation.
- DPIA / RIPD: the Personal Data Protection Impact Assessment (RIPD, the national equivalent of the Data Protection Impact Assessment) documents high-risk processing, the threats to privacy and the mitigation measures. It is the instrument that proves, before the ANPD, that privacy was considered from the design stage.
Integration with DevSecOps
Security by Design only scales when it stops depending on a manual gate and starts living in the pipeline. In a DevSecOps culture, the principles translate into automation:
- Static analysis (SAST) and dependency analysis (SCA) on every commit, blocking builds with critical vulnerabilities.
- Dynamic analysis (DAST) and configuration testing of infrastructure as code.
- Secrets management outside the code, with automatic rotation.
- Least-privilege policies applied as code in cloud environments.
- Lightweight, continuous threat modeling on every new feature, not just at project start.
OWASP SAMM helps measure the maturity of this process across functions like Governance, Design, Implementation, Verification and Operations, allowing you to evolve in a planned way rather than sporadically. Instead of trying to "do everything at once," the organization assesses where it stands in each practice, sets a realistic target level and invests in the highest-risk gaps. This turns security from a diffuse cost into a measurable program, with indicators that leadership can track.
It is worth stressing that DevSecOps does not dilute responsibility for security among developers to the point of eliminating it; on the contrary, it equips each team with automated guardrails and keeps security specialists as enablers and reviewers of high-risk decisions. Automation handles the volume — thousands of dependencies, configurations and commits — while human judgment focuses on threat design and exceptions. It is this division that makes it possible to maintain delivery speed without giving up protection.
Positive-sum, not trade-off
Cavoukian's fourth principle deserves emphasis for an executive audience: well-designed privacy and security do not compete with user experience or with the business — they sustain it. Trust is a commercial asset. Companies that treat data protection as a differentiator reduce friction in B2B sales, pass client audits with less friction and avoid the disproportionate cost of an incident. The "positive-sum" is, in the end, a value thesis.
How Decripte helps
Decripte is a B2B cybersecurity company that helps organizations of every size — from 1 to more than 100,000 employees — embed Security by Design and Privacy by Design in a practical way: from threat modeling and architecture review to LGPD compliance (arts. 46 and 49), covering DevSecOps, data minimization and RIPD preparation. Our platform turns principles into verifiable controls, with continuous visibility into the real risk of your environment.
Want to start with visibility? Start for free with our Intelligence Center and discover your organization's exposure before any attacker does. To implement and manage protection end to end, explore our plans — cybersecurity for all sizes, from micro-business to Enterprise.