Security Core

Comprehensive application security guidance for TypeScript, Python, and Rust applications.

Quick Start

Common Security Tasks

Setting up authentication:

1. Generate JWT keys: ./scripts/generate_jwt_keys.sh RS256
2. Consult authentication.md for implementation patterns
3. Use security templates from assets/configs/

Implementing authorization:

1. Review authorization.md for RBAC/ABAC/RLS patterns
2. For Supabase: See RLS section with multi-tenant examples
3. Implement permission checking at API and database layers

Security auditing:

1. Run: ./scripts/audit_security.sh
2. Review code-review.md checklist
3. Check owasp-top-10.md for vulnerabilities

Hardening application:

1. Apply security headers from security-headers.md
2. Implement rate limiting from rate-limiting.md
3. Configure secrets management per secrets-management.md

When to Use This Skill

Authentication Scenarios

• Implementing login/signup flows
• Adding JWT or session-based authentication
• Integrating OAuth 2.0 providers
• OAuth for CLI, TUI, or desktop applications (Device Flow)
• Multi-factor authentication (TOTP, SMS/Email OTP)
• Password hashing and validation

Authorization Scenarios

• Role-Based Access Control (RBAC)
• Attribute-Based Access Control (ABAC)
• Row Level Security (RLS) with Supabase/PostgreSQL
• Multi-tenant data isolation
• Permission-based access control
• Resource ownership validation

Security Auditing

• Code security reviews
• Dependency vulnerability scanning
• OWASP Top 10 compliance checks
• Secret detection in code
• Security configuration verification

Infrastructure Security

• Security headers (CSP, HSTS, X-Frame-Options)
• CORS configuration
• Rate limiting implementation
• Secrets management
• API security hardening

Core Resources

Scripts (scripts/)

audit_security.sh - Security audit for TypeScript, Python, and Rust projects

• Runs dependency vulnerability scanners (npm audit, pip-audit, cargo-audit)
• Detects hardcoded secrets in code
• Checks for common security misconfigurations
• Usage: ./scripts/audit_security.sh [project-directory]

generate_jwt_keys.sh - Generate secure JWT signing keys

• Supports HS256 (symmetric), RS256 (asymmetric), ES256 (elliptic curve)
• Automatically adds keys to .gitignore
• Provides usage examples
• Usage: ./scripts/generate_jwt_keys.sh [ALGORITHM] [OUTPUT_DIR]

Reference Documentation (references/)

authentication.md - Complete authentication guide

• JWT implementation (TypeScript, Python, Rust)
• Session-based authentication
• OAuth 2.0 Authorization Code Flow
• OAuth Device Flow for CLI/TUI/desktop apps ⭐
• Multi-factor authentication (TOTP, SMS)
• Password security and hashing
• Token storage best practices

authorization.md - Authorization patterns and implementations

• Role-Based Access Control (RBAC)
• Attribute-Based Access Control (ABAC)
• Row Level Security (RLS) with Supabase/PostgreSQL ⭐
• Multi-tenant RLS patterns
• Permission checking patterns
• Resource-based authorization
• Testing authorization logic

owasp-top-10.md - OWASP Top 10 prevention guide

• A01: Broken Access Control
• A02: Cryptographic Failures
• A03: Injection (SQL, NoSQL, Command)
• A04: Insecure Design
• A05: Security Misconfiguration
• A06: Vulnerable Components
• A07: Authentication Failures
• A08: Data Integrity Failures
• A09: Logging & Monitoring Failures
• A10: Server-Side Request Forgery (SSRF)

secrets-management.md - Secrets and credentials management

• Environment variables best practices
• Secret managers (AWS Secrets Manager, HashiCorp Vault)
• Secret rotation strategies
• CI/CD secrets handling
• Local development with .env files

security-headers.md - HTTP security headers

• Content-Security-Policy (CSP)
• Strict-Transport-Security (HSTS)
• X-Frame-Options, X-Content-Type-Options
• CORS configuration
• Implementation examples for all frameworks

rate-limiting.md - Rate limiting strategies

• Fixed window, sliding window, token bucket
• Implementation in TypeScript, Python, Rust
• Distributed rate limiting with Redis
• Per-user and per-IP limiting
• Rate limit headers and responses

code-review.md - Security code review checklist

• Authentication & authorization checks
• Input validation & sanitization
• Data protection and encryption
• Security headers & configuration
• Session management
• API security
• Common vulnerabilities (XSS, CSRF, SQL injection)

Configuration Templates (assets/configs/)

Ready-to-use security middleware for all supported languages:

TypeScript: assets/configs/typescript/security-config.ts

• Express + Helmet configuration
• CORS setup
• Rate limiting
• Security headers

Python: assets/configs/python/security_middleware.py

• FastAPI middleware
• Security headers
• CORS
• Rate limiting with slowapi

Rust: assets/configs/rust/security_middleware.rs

• Axum middleware
• tower-http CORS layer
• Security headers

Decision Guides

Choosing Authentication Method

Method	Use When	Complexity	Best For
JWT	Stateless APIs, microservices	Medium	SPAs, mobile apps, APIs
Sessions	Traditional web apps	Low	Server-rendered apps
OAuth 2.0	Third-party auth, SSO	High	Delegated authentication
API Keys	Service-to-service	Low	Internal services

See authentication.md for detailed implementation patterns.

Choosing Authorization Model

Model	Use When	Complexity	Best For
RBAC	Simple role hierarchies	Low	Standard web apps
ABAC	Complex, dynamic policies	High	Enterprise apps
RLS	Multi-tenant with data isolation	Medium	SaaS applications
Permissions	Fine-grained control	Medium	Admin panels, APIs

See authorization.md for implementation patterns and RLS examples.

OAuth for CLI/TUI/Desktop

For applications without traditional browser redirects:

Device Authorization Flow (OAuth 2.0):

1. App requests device code
2. User opens browser and enters code
3. App polls for token
4. Token granted after user approval

Full implementation examples in authentication.md - OAuth for CLI, TUI, and Desktop Apps.

Common Workflows

1. Implementing JWT Authentication

# Generate keys
./scripts/generate_jwt_keys.sh RS256 ./keys

# Review implementation patterns
# See references/authentication.md#jwt-authentication

Then implement using examples for your language (TypeScript/Python/Rust).

2. Adding Row Level Security (Supabase)

# Review RLS patterns
# See references/authorization.md#row-level-security-rls

Implement RLS policies for multi-tenant isolation:

• Enable RLS on tables
• Create policies for SELECT, INSERT, UPDATE, DELETE
• Use helper functions for complex rules
• Test with different user contexts

3. Security Audit Workflow

# Run automated audit
./scripts/audit_security.sh

# Manual review
# 1. Check references/code-review.md checklist
# 2. Review references/owasp-top-10.md for vulnerabilities
# 3. Verify security headers with references/security-headers.md
# 4. Test rate limiting per references/rate-limiting.md

4. Hardening New Application

1. Apply security templates:

   • Copy appropriate config from assets/configs/[language]/
   • Configure CORS for your domains
   • Set up rate limiting

2. Implement authentication:

   • Choose method from authentication.md
   • Generate secure keys
   • Configure token expiration

3. Add authorization:

   • Choose model from authorization.md
   • Implement permission checks
   • Enable RLS if multi-tenant

4. Configure security headers:

   • Follow security-headers.md
   • Test with online tools

5. Set up secrets management:

   • Follow secrets-management.md
   • Use environment variables or secret manager

6. Review OWASP Top 10:

   • Check owasp-top-10.md
   • Ensure all risks are mitigated

Language-Specific Guidance

TypeScript/Node.js

• Use Helmet for security headers
• Validate inputs with Zod
• Use prepared statements for SQL
• Hash passwords with bcrypt
• See config: assets/configs/typescript/security-config.ts

Python/FastAPI

• Use Pydantic for validation
• Parameterized queries only
• Hash passwords with bcrypt
• Security middleware in startup
• See config: assets/configs/python/security_middleware.py

Rust

• Compiler prevents many issues
• Validate at boundaries
• Use sqlx for type-safe SQL
• Hash passwords with argon2
• See config: assets/configs/rust/security_middleware.rs

Best Practices

1. Defense in Depth - Multiple security layers
2. Least Privilege - Grant minimum necessary permissions
3. Fail Securely - Default to deny
4. Keep Secrets Secret - Never commit credentials
5. Validate Everything - All inputs at boundaries
6. Use Strong Crypto - Modern algorithms only
7. Log Security Events - Authentication, authorization failures
8. Update Dependencies - Regular security patches
9. Rate Limit - Protect against abuse
10. Test Security - Automated security tests

Testing Security

Write tests for security concerns:

// Authentication tests
it('should reject invalid credentials');
it('should rate limit login attempts');
it('should require MFA when enabled');

// Authorization tests
it('should deny unauthorized access');
it('should allow access for correct role');
it('should enforce resource ownership');

// Input validation tests
it('should prevent SQL injection');
it('should sanitize HTML input');
it('should validate file uploads');

See code-review.md for complete testing checklist.

Security Resources

Primary references in this skill:

• authentication.md - Auth patterns and OAuth for CLI/desktop
• authorization.md - RBAC, ABAC, and RLS
• owasp-top-10.md - Top web vulnerabilities
• secrets-management.md - Credential handling
• security-headers.md - HTTP security headers
• rate-limiting.md - API protection
• code-review.md - Security review checklist

External resources:

• OWASP Top 10
• OWASP Cheat Sheet Series
• Security Headers
• Mozilla Web Security Guidelines

Getting Started

For a new secure application:

1. Review Best Practices section
2. Apply security templates from assets/configs/
3. Implement authentication from authentication.md
4. Add authorization from authorization.md
5. Configure security headers from security-headers.md
6. Run ./scripts/audit_security.sh to verify

For security review:

1. Run ./scripts/audit_security.sh
2. Follow code-review.md checklist
3. Check owasp-top-10.md for vulnerabilities

For specific security concern:

• Authentication issue → authentication.md
• Authorization issue → authorization.md
• OWASP vulnerability → owasp-top-10.md
• Configuration issue → security-headers.md or rate-limiting.md
• Secrets issue → secrets-management.md