Design a secure trading app on AWS

## Scenario Design a **secure, Robinhood-like mobile/web application on AWS**, with a deep dive into: 1. **User profile management** (account creation, authentication, PII storage, profile updates) 2. **Stock query** (searching symbols and retrieving near-real-time quotes) Assume this is a regulated financial product (PII, auditability, strong security). You may treat **order placement/execution** as out of scope unless needed for completeness. ## Functional requirements ### User profile management - Sign up / sign in / sign out - MFA support - Store and manage user profile data (name, email/phone, address, KYC status, preferences) - Allow profile updates (with appropriate authorization and audit trail) - Account recovery (password reset) ### Stock query - Search stocks by ticker/company name (prefix search) - Fetch a quote for a symbol (price, bid/ask, timestamp) - Handle high read QPS with low latency ## Non-functional requirements - Strong security: encryption, least privilege, secrets management, WAF/rate limiting - Compliance/audit: immutable logs of profile changes and access - High availability and scalability - Reasonable freshness for quotes (e.g., seconds), with graceful degradation ## Deliverables - High-level architecture on AWS - Key data models/stores - API surface (example endpoints) - Security model and threat mitigations - Scalability and reliability approach (caching, multi-AZ/region, DR)