SafeCase

Mobile-first case management for child protection field workers of War Child. Built for humanitarian contexts where internet access is unreliable or unavailable: cases are captured on-device, stored encrypted at rest, and transferred to a supervisor either over a local network or directly between devices.

Developed at the Whale x Anthropic hackathon (Event link on Luma). Built entirely with Claude Code by Team23:

• Quinten van der Laan
• Brian Jacobs
• Ally Alombro
• Tutku Çakır Yılmaz
• Marie Shulgina

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Overview

Field workers operate entirely offline. They record child protection cases using structured CPMS forms on their device. When data needs to reach a supervisor, it is transferred app-to-app - no cloud connection required at that stage. The supervisor reviews, approves, and then pushes the consolidated data to the backend when connectivity is available.

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Screenshots

Sign in	Caseworker dashboard	Cases list (encrypted)
Adding and signing a new case	Cases ready to sync	Supervisor — upload to cloud

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Features

Offline-first case management

All case data is captured and stored locally on the device. Caseworkers are never blocked by connectivity. The app supports the full CPMS form set:

Form	Name
1A	Consent
1B	Registration & Rapid Assessment
2	Comprehensive Assessment

Each form is rendered step-by-step by a schema-driven FormWizard component. Fields include text, date pickers, enumerations, multi-select, integer inputs, and digital signature capture.

Encryption at rest

All case data passes through frontend/modules/encryptionModule.js before touching storage. The pipeline is:

raw form object → compact field keys → gzip (pako deflate) → AES-256-GCM → base64

The AES-256-GCM key is derived from the user's PIN and device ID via PBKDF2-SHA256 at 100,000 iterations (OWASP 2024 minimum). The derived key is stored in the device secure enclave via expo-secure-store and never written to AsyncStorage or plain files. A fresh 12-byte IV is generated for every encryption call via a CSPRNG, so identical inputs always produce different ciphertexts. GCM authentication guarantees that any tampered or corrupted blob is rejected on read rather than returning corrupt data.

The lock icon shown on each case card in the Cases list confirms the record is stored in this encrypted form.

Role-based access

Two roles govern the application:

• Caseworker (user) — records cases offline, initiates sync to a supervisor. Has no direct access to the backend API.
• Supervisor — receives data from caseworkers, reviews and approves submissions locally, then uploads approved files to the backend. Has an additional Upload tab visible in the navigation.

App-to-app sync

Caseworkers push completed cases to a supervisor's device over a local network connection. The supervisor reviews the incoming data, selects which cases to approve, and queues them for cloud upload. No internet is required for this stage.

Cloud upload (supervisor only)

Once a supervisor has approved submissions, they can upload the consolidated CSV files to the backend API over HTTPS. The Upload tab lists all pending files with their origin field worker, sector, and timestamp.

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Architecture

Repository layout

team23/
├── backend/          Laravel 13 REST API (PHP 8.4, SQLite, Docker)
└── frontend/         Expo + React Native (TypeScript, Expo Router)

Each directory is an independent application with its own dependencies and its own CLAUDE.md.

Frontend

• Framework: React Native (TypeScript). Expo is used as the development and testing environment — the production target is a standard native binary (iOS / Android) built via EAS Build or a bare workflow export.
• Navigation: Expo Router (file-based). Two route groups: (auth) for login, (tabs) for the main app.
• Local storage: AsyncStorage for case metadata; expo-file-system CSV files for form content via services/csvService.ts.
• Encryption: frontend/modules/encryptionModule.js — AES-256-GCM with PBKDF2-SHA256 key derivation; uses Web Crypto (Hermes) with an expo-crypto fallback for pre-Hermes builds. Keys stored via expo-secure-store.
• Forms: Defined as FormDefinition objects in frontend/data/forms.ts. The FormWizard component renders them step-by-step with FormFieldInput handling each field type.
• Styling: Centralised DashboardColors palette in constants/dashboard-colors.ts. No Tailwind.

Backend

• Framework: Laravel 13 (PHP 8.4)
• Auth: Laravel Sanctum token authentication
• Database: SQLite in development, configurable via .env
• API: All routes under /api/, gated by auth + supervisor middleware. Case routes are nested: GET|POST /api/cases/{case_id}/form-1a, etc.
• Models: Form1aSubmission, Form1bSubmission, Form2Submission

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Getting started

Prerequisites

• Docker and Docker Compose (backend)
• Node.js 20+ and npm (frontend)
• Expo Go on a physical device or an iOS/Android simulator (development and testing only)

Backend

cd backend
touch database/database.sqlite
cp .env.example .env

From the repository root:

make up           # build images and start containers
make sh-backend      # open a shell inside the backend container

Inside the container:

php artisan key:generate
exit

Back at the root:

make db-fresh     # run migrations and seed the database

The API will be available at http://localhost:8000.

Frontend

cd frontend
npm install
npx expo start    # choose platform interactively (iOS / Android / Web)

The frontend connects to http://localhost:8000 in development (see frontend/constants/configs.ts).

Useful make targets

Command	Description
make up	Build and start the backend in Docker
make down	Stop containers
make logs	Tail container logs
make test	Run backend tests inside Docker
make backend	Open a shell in the backend container
make db-fresh	Drop, migrate, and seed the database

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Planned

Bluetooth peer-to-peer sync

Direct device-to-device data transfer over Bluetooth Low Energy for environments with no local network. Planned to include delta sync, conflict flagging, and verbal PIN pairing for secure device authentication.

Organisation key distribution

Secure transfer of the organisation encryption key to newly provisioned devices without requiring an internet connection.

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Tech stack

Layer	Technology
Mobile app	React Native, TypeScript
Dev / test environment	Expo SDK, Expo Go
Navigation	Expo Router
Encryption	AES-256-GCM, PBKDF2-SHA256, Web Crypto / expo-crypto
Secure key storage	expo-secure-store
Local persistence	AsyncStorage, expo-file-system
Backend API	Laravel 13, PHP 8.4
Authentication	Laravel Sanctum
Database	SQLite (dev)
Infrastructure	Docker, Docker Compose