crowd-funder-for-time-pwa/doc/secure-storage-implementation.md

Secure Storage Implementation Guide for TimeSafari App

Overview

This document outlines the implementation of secure storage for the TimeSafari app using a platform-agnostic approach with Capacitor and absurd-sql solutions. The implementation focuses on:

1. Platform-Specific Storage Solutions:

   • Web: absurd-sql with IndexedDB backend and Web Worker support
   • iOS/Android: Capacitor SQLite with native SQLite implementation
   • Electron: Node SQLite (planned, not implemented)

2. Key Features:

   • Platform-agnostic SQLite interface
   • Web Worker support for web platform
   • Consistent API across platforms
   • Performance optimizations (WAL, mmap)
   • Comprehensive error handling and logging
   • Type-safe database operations
   • Storage quota management
   • Platform-specific security features

Architecture

The storage implementation follows a layered architecture:

1. Platform Service Layer

   • PlatformService interface defines platform capabilities
   • Platform-specific implementations:
     • WebPlatformService: Web platform with absurd-sql
     • CapacitorPlatformService: Mobile platforms with native SQLite
     • ElectronPlatformService: Desktop platform (planned)
   • Platform detection and capability reporting
   • Storage quota and feature detection

2. SQLite Service Layer

   • SQLiteOperations interface for database operations
   • Base implementation in BaseSQLiteService
   • Platform-specific implementations:
     • AbsurdSQLService: Web platform with Web Worker
     • CapacitorSQLiteService: Mobile platforms with native SQLite
     • ElectronSQLiteService: Desktop platform (planned)
   • Common features:
     • Transaction support
     • Prepared statements
     • Performance monitoring
     • Error handling
     • Database statistics

3. Data Access Layer

   • Type-safe database operations
   • Transaction support
   • Prepared statements
   • Performance monitoring
   • Error recovery
   • Data integrity verification

Implementation Details

Web Platform (absurd-sql)

The web implementation uses absurd-sql with the following features:

1. Web Worker Support

   • SQLite operations run in a dedicated worker thread
   • Main thread remains responsive
   • SharedArrayBuffer support when available
   • Worker initialization in sqlite.worker.ts

2. IndexedDB Backend

   • Persistent storage using IndexedDB
   • Automatic data synchronization
   • Storage quota management (1GB limit)
   • Virtual file system configuration

3. Performance Optimizations

   • WAL mode for better concurrency
   • Memory-mapped I/O (30GB when available)
   • Prepared statement caching
   • 2MB cache size
   • Configurable performance settings

Example configuration:

const webConfig: SQLiteConfig = {
  name: 'timesafari',
  useWAL: true,
  useMMap: typeof SharedArrayBuffer !== 'undefined',
  mmapSize: 30000000000,
  usePreparedStatements: true,
  maxPreparedStatements: 100
};

Mobile Platform (Capacitor SQLite)

The mobile implementation uses Capacitor SQLite with:

1. Native SQLite

   • Direct access to platform SQLite
   • Native performance
   • Platform-specific optimizations
   • 2GB storage limit

2. Platform Integration

   • iOS: Native SQLite with WAL support
   • Android: Native SQLite with WAL support
   • Platform-specific permissions handling
   • Storage quota management

Example configuration:

const mobileConfig: SQLiteConfig = {
  name: 'timesafari',
  useWAL: true,
  useMMap: false, // Not supported on mobile
  usePreparedStatements: true
};

Database Schema

The implementation uses the following schema:

-- Accounts table
CREATE TABLE accounts (
  did TEXT PRIMARY KEY,
  public_key_hex TEXT NOT NULL,
  created_at INTEGER NOT NULL,
  updated_at INTEGER NOT NULL
);

-- Settings table
CREATE TABLE settings (
  key TEXT PRIMARY KEY,
  value TEXT NOT NULL,
  updated_at INTEGER NOT NULL
);

-- Contacts table
CREATE TABLE contacts (
  id TEXT PRIMARY KEY,
  did TEXT NOT NULL,
  name TEXT,
  created_at INTEGER NOT NULL,
  updated_at INTEGER NOT NULL,
  FOREIGN KEY (did) REFERENCES accounts(did)
);

-- Performance indexes
CREATE INDEX idx_accounts_created_at ON accounts(created_at);
CREATE INDEX idx_contacts_did ON contacts(did);
CREATE INDEX idx_settings_updated_at ON settings(updated_at);

Error Handling

The implementation includes comprehensive error handling:

1. Error Types

export enum StorageErrorCodes {
  INITIALIZATION_FAILED = 'STORAGE_INIT_FAILED',
  QUERY_FAILED = 'STORAGE_QUERY_FAILED',
  TRANSACTION_FAILED = 'STORAGE_TRANSACTION_FAILED',
  PREPARED_STATEMENT_FAILED = 'STORAGE_PREPARED_STATEMENT_FAILED',
  DATABASE_CORRUPTED = 'STORAGE_DB_CORRUPTED',
  STORAGE_FULL = 'STORAGE_FULL',
  CONCURRENT_ACCESS = 'STORAGE_CONCURRENT_ACCESS'
}

2. Error Recovery
   • Automatic transaction rollback
   • Connection recovery
   • Data integrity verification
   • Platform-specific error handling
   • Comprehensive logging

Performance Monitoring

The implementation includes built-in performance monitoring:

1. Statistics

interface SQLiteStats {
  totalQueries: number;
  avgExecutionTime: number;
  preparedStatements: number;
  databaseSize: number;
  walMode: boolean;
  mmapActive: boolean;
}

2. Monitoring Features
   • Query execution time tracking
   • Database size monitoring
   • Prepared statement usage
   • WAL and mmap status
   • Platform-specific metrics

Security Considerations

1. Web Platform

   • Worker thread isolation
   • Storage quota monitoring
   • Origin isolation
   • Cross-origin protection
   • SharedArrayBuffer availability check

2. Mobile Platform

   • Platform-specific permissions
   • Storage access control
   • File system security
   • Platform sandboxing

Testing Strategy

1. Unit Tests

   • Platform service tests
   • SQLite service tests
   • Error handling tests
   • Performance tests

2. Integration Tests

   • Cross-platform tests
   • Migration tests
   • Transaction tests
   • Concurrency tests

3. E2E Tests

   • Platform-specific workflows
   • Error recovery scenarios
   • Performance benchmarks
   • Data integrity verification

Success Criteria

1. Performance

   • Query response time < 100ms
   • Transaction completion < 500ms
   • Memory usage < 50MB
   • Database size < platform limits:
     • Web: 1GB
     • Mobile: 2GB

2. Reliability

   • 99.9% uptime
   • Zero data loss
   • Automatic recovery
   • Transaction atomicity

3. Security

   • Platform-specific security features
   • Storage access control
   • Data protection
   • Audit logging

4. User Experience

   • Smooth platform transitions
   • Clear error messages
   • Progress indicators
   • Recovery options

Future Improvements

1. Planned Features

   • SQLCipher integration for mobile
   • Electron platform support
   • Advanced backup/restore
   • Cross-platform sync

2. Security Enhancements

   • Biometric authentication
   • Secure enclave usage
   • Advanced encryption
   • Key management

3. Performance Optimizations

   • Advanced caching
   • Query optimization
   • Memory management
   • Storage efficiency