Identity
Every sensitive operation is tied to an authenticated identity.
CASE STUDY · API SECURITY · ZERO TRUST
Zero Trust API
Production-deployed financial security laboratory demonstrating JWT authentication, role-based authorization and PostgreSQL Row-Level Security with Neon, Express and automated security verification.
01
THE PROBLEM
Financial APIs require stronger trust boundaries.
Traditional perimeter-based security models assume that internal traffic can be trusted. Modern distributed applications require a stricter model where every request is evaluated based on identity, permissions and context.
02
SECURITY MODEL
Never trust implicitly. Verify every request.
Authorization
Access decisions depend on permissions rather than network location.
Least Privilege
Users and services receive only the access required for their role.
Continuous Validation
Requests are treated as untrusted until security requirements are satisfied.
03
ARCHITECTURE
Security controls integrated across the application.
01Client
User-facing application and request origin
02Identity
Authentication and session validation
03Authorization
Permission and role-based access decisions
04API
Protected financial operations and business logic
05Data
Controlled persistence and database access
04
DEFENSIVE ENGINEERING
Security designed into the workflow.
Access Control
Sensitive application functions are protected through explicit access rules.
Input Validation
Untrusted input is treated as a security boundary and validated before processing.
Data Protection
Application and database boundaries are designed to minimize unnecessary data exposure.
Auditability
Security-sensitive operations can be structured for traceability and review.
05
TESTING STRATEGY
Testing security behavior, not just happy paths.
Authentication Tests
Validate protected access and unauthenticated behavior.
Authorization Tests
Verify that restricted operations reject insufficient privileges.
API Validation
Check expected responses, error handling and request boundaries.
Negative Testing
Exercise invalid and unauthorized scenarios intentionally.
06
SECURITY VERIFICATION
Automated proof that access control is enforced.
401 Without JWT
Protected transaction endpoints reject requests that do not provide an Authorization Bearer token.
403 Invalid JWT
Invalid or malformed tokens are rejected before any database access is attempted.
Branch Isolation
The gerente10 role was verified against 50 returned records, with every transaction restricted to sucursal_id 10.
Regional Auditor Access
The auditor_regional role was verified with multi-branch visibility while PostgreSQL RLS remained the authorization boundary.
01JWT
Authenticated identity established
02Role Context
Application role injected into PostgreSQL
03RLS
Database filters rows according to authorization policy
04Automated Test
Security behavior verified end-to-end in production
0 Dependency Vulnerabilities
The production dependency tree was verified with npm audit reporting zero known vulnerabilities.
Security Headers
Production responses include protections such as X-Content-Type-Options, X-Frame-Options, Referrer-Policy and Permissions-Policy.
No Sensitive Caching
Authentication and protected financial endpoints explicitly return Cache-Control: no-store.
Production Deployment
The hardened API is deployed on Vercel and connected to Neon PostgreSQL with runtime secrets stored as environment variables.
Authentication identities in this project are intentionally mocked for demonstration and security-testing purposes. The portfolio case study focuses on authorization, JWT verification, database-enforced Row-Level Security and defensive API design rather than production identity management.
07
TECHNOLOGY
Technology stack.
Zero TrustAPI SecurityNode.jsExpressJWTPostgreSQLNeonRow-Level SecurityVercel
08
OUTCOME
A portfolio project combining backend engineering and security.
Zero Trust API Financiera demonstrates how software engineering, API design and defensive security principles can be combined in a practical application instead of being treated as separate topics.