# Technical Specification: YouTube MCP Server Authentication and Security
## Overview
This document provides the technical details for securing the YouTube MCP server. The implementation will include API key authentication, multi-tenancy, rate limiting, usage quotas, and billing integration.
## Architecture / System Design
### Components
1. **Authentication Layer**: Enforces API key authentication for all API requests.
2. **Rate Limiter**: Limits API requests per IP and per token.
3. **Multi-Tenancy**: Supports account-based API key management.
4. **Usage Tracker**: Tracks API usage and enforces quotas.
5. **Billing System**: Integrates with Stripe for subscription management.
6. **Observability Tools**: Logs API usage, errors, and performance metrics.
7. **Deployment**: Containerized application deployable on scalable platforms.
### Data Flow
1. User retrieves their API key from the frontend application.
2. API requests include the API key in the `Authorization` header (e.g., `Bearer YOUR_API_KEY`).
3. The system validates the API key and checks rate limits and quotas.
4. Requests are processed, and usage is logged.
5. Billing system handles plan upgrades and payments.
## Data Models
### Account
- `id`: UUID
- `email`: String
- `plan`: Enum (Free, Pro, Enterprise)
- `api_keys`: Array of API keys
- `usage`: Object (tracks API usage per tool)
### API Key
- `id`: UUID
- `account_id`: UUID (foreign key to Account)
- `key`: String (hashed)
- `created_at`: Timestamp
- `last_used_at`: Timestamp
### Usage
- `account_id`: UUID (foreign key to Account)
- `tool`: String
- `requests`: Integer
- `quota`: Integer
## API Design
### Authentication
- **Method**: API Key in `Authorization` header.
- **Description**: Validates the API key for each request.
### Rate Limiting
- **Middleware**: `rateLimiter`
- **Description**: Limits requests per IP and per token.
## Logic and Behaviour
1. **Authentication**: Validate API keys against the database.
2. **Rate Limiting**: Use `express-rate-limit` to enforce per-IP and per-token limits.
3. **Usage Tracking**: Increment usage counters for each API request.
4. **Quota Enforcement**: Reject requests that exceed the user's quota.
5. **Billing**: Update quotas and unlock features upon successful payment.
6. **Observability**: Log account ID, tool name, latency, and status for each request.
## Tech Stack & Dependencies
- **Framework**: XMCP
- **Authentication**: API Key (validated against Supabase DB)
- **Rate Limiting**: `express-rate-limit`
- **Database**: Supabase (PostgreSQL)
- **Billing**: Stripe
- **Deployment**: Vercel (serverless architecture)
## Updated Components
### Authentication Layer
- Use API keys for authentication.
- Validate API keys by looking them up in the Supabase database.
- The server will expect the API key to be passed in the `Authorization` header.
### Database
- Use Supabase's PostgreSQL database for storing user accounts, API keys, and usage metrics.
- Leverage Supabase's Row-Level Security (RLS) to enforce multi-tenancy.
- Optimize database queries to stay within the limits of the Supabase free plan.
### Observability
- Use Supabase's built-in logging and monitoring tools to track database queries and authentication events.
## Implementation Steps
1. Set up a Supabase project.
2. Update the XMCP server to validate API keys from the `Authorization` header.
3. Design database schemas for accounts, API keys, and usage metrics in Supabase.
4. Implement Row-Level Security (RLS) policies for multi-tenancy.
5. Optimize database queries to minimize resource usage and stay within the Supabase free plan limits.
6. Monitor Supabase usage and adjust configurations as needed to avoid exceeding free plan quotas.
## Security & Privacy Considerations
- Enforce HTTPS for all API endpoints.
- Store secrets (e.g., JWT secret, Stripe API key) in environment variables.
- Hash API keys before storing them in the database.
- Comply with GDPR and CCPA regulations.
## Performance Considerations
- Optimize database queries for usage tracking.
- Use caching for frequently accessed data (e.g., account details).
- Scale horizontally by deploying multiple instances behind a load balancer.
## Risks & Mitigations
- **Risk**: Abuse of free-tier API keys.
- **Mitigation**: Enforce strict rate limits and quotas.
- **Risk**: API key leakage.
- **Mitigation**: Allow users to regenerate keys and use short-lived tokens where appropriate.
- **Risk**: Downtime during scaling.
- **Mitigation**: Use zero-downtime deployment strategies.
