quicknotes/specs/authentication.md

Authentication Specification

Overview

The QuickNotes application is designed primarily for local use and does not currently implement a comprehensive authentication system. This document outlines the current state of authentication in the application and potential future enhancements.

Current Implementation

Local Usage Model

QuickNotes currently operates on a local-only model:

1. The application runs as a local server on the user's machine
2. Access is restricted to localhost connections
3. No user accounts or login functionality is implemented
4. All data is stored locally in the SQLite database

Security Considerations

Despite the lack of formal authentication, the application implements several security measures:

1. Trusted Proxies: The application only trusts loopback addresses (127.0.0.1, ::1)
2. Input Validation: All user inputs are validated to prevent injection attacks
3. Content Security Policy: Headers are set to prevent cross-site scripting
4. CSRF Protection: The application includes measures to prevent cross-site request forgery

Potential Future Authentication

If authentication were to be implemented in the future, the following approach could be adopted:

User Model

A potential User entity would have the following attributes:

Field	Type	Description
ID	string	Unique identifier for the user (UUID)
Username	string	Username for login
PasswordHash	string	Hashed password (not stored in plaintext)
Email	string	User's email address
CreatedAt	timestamp	When the user account was created
UpdatedAt	timestamp	When the user account was last updated

Authentication Flow

1. Registration: Users would create an account with a username and password
2. Login: Users would authenticate with their credentials
3. Session Management: Authenticated sessions would be maintained using JWT or session cookies
4. Logout: Users would be able to terminate their sessions

API Endpoints

Method	Endpoint	Description
POST	/api/auth/register	Register a new user
POST	/api/auth/login	Authenticate a user
POST	/api/auth/logout	End a user's session
GET	/api/auth/me	Get the current user's information
PUT	/api/auth/password	Change a user's password

Multi-User Support

With authentication, the application could support multiple users:

1. Data Isolation: Each user would only see their own notes, readlist items, and feeds
2. User Preferences: Users could have individual settings and preferences
3. Sharing: Users could optionally share specific notes or collections with other users

Security Enhancements

Authentication would bring additional security measures:

1. Password Hashing: Using bcrypt or Argon2 for secure password storage
2. Rate Limiting: Preventing brute force attacks
3. Two-Factor Authentication: Optional additional security layer
4. API Tokens: For programmatic access to the API

Integration with Emacs Mode

The Emacs mode would need to be updated to support authentication:

1. Credential Storage: Securely storing user credentials
2. Authentication Flow: Handling login and session management
3. Token Refresh: Automatically refreshing expired tokens

Implementation Considerations

If authentication were to be implemented, the following considerations would be important:

1. Backward Compatibility: Ensuring existing data can be migrated to user accounts
2. Simplicity: Maintaining the application's ease of use
3. Privacy: Ensuring user data remains private and secure
4. Performance: Minimizing the performance impact of authentication checks