---
description: Cryptography and security rules - E2E encryption, key management, storage
globs: "**/crypto/**,**/*.ts"
alwaysApply: false
---

# Security & Cryptography

## Principles
- Privacy is a requirement, not a feature
- Zero telemetry, zero analytics unless user explicitly opts in
- Never transmit unencrypted sensitive data
- Never store plaintext credentials
- Minimal data collection — store only what's needed

## Encryption Stack

### E2E Message Encryption
- Library: **tweetnacl.js** (6KB, audited by Cure53)
- Algorithm: XSalsa20-Poly1305 via NaCl `box` (public-key authenticated encryption)
- Each conversation has a shared secret derived from key exchange

### Local Storage Encryption
- Library: **Web Crypto API** (native, zero bundle cost)
- Algorithm: AES-256-GCM for encrypting IndexedDB values
- Key derived from user's master password via PBKDF2 (100K+ iterations)

### Key Management
- **Desktop (Tauri)**: OS keychain (macOS Keychain, Windows Credential Manager, Linux Secret Service)
- **Web**: Encrypted IndexedDB with user-derived key
- **Nostr compatibility**: secp256k1 keys via @noble/curves, NIP-07 browser extension support
- **Passkeys/WebAuthn**: For passwordless authentication

### Credential Storage
- API keys encrypted at rest using AES-256-GCM
- Never stored in localStorage (use encrypted IndexedDB or OS keychain)
- Never included in logs, error reports, or system prompts
- Display as masked values in settings UI (show last 4 chars only)

## Dev Mode Bypass
When `VITE_DISABLE_CRYPTO=true` (dev only):
- Skip E2E encryption (messages stored in plain text)
- Skip storage encryption (IndexedDB unencrypted)
- API keys stored in `.env.local` (gitignored)
- This flag must NEVER exist in production builds

## Security Rules for Code
- Never log sensitive data (keys, tokens, passwords, message content)
- Never include secrets in error messages
- Sanitize all user input before rendering (XSS prevention)
- Use Content Security Policy headers
- Validate all data from plugins before rendering
- Community plugins run in sandboxed iframes (no direct DOM access)
- Never eval() or innerHTML with untrusted content

## Network Security
- All external requests over HTTPS only
- Certificate pinning for known services (Tauri)
- Proxy social media fetches to avoid leaking user IP
- No third-party tracking scripts, analytics, or telemetry SDKs