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LFPH COVID Shield

LFPH COVID Shield is an open-source implementation of a privacy-preserving exposure notification system (public health / mobile exposure notification) built to help public health authorities deploy Bluetooth-based COVID-19 contact notification apps using the Google Apple Exposure Notification (GAEN) framework.

  • Open-source exposure notification reference implementation for public health authorities (public health / mobile exposure notification).
  • Includes mobile applications for iOS and Android that use the GAEN framework for Bluetooth-based proximity detection (mobile client / Software Development Kit (SDK) integration).
  • Provides a backend server for processing one-time codes, registering devices, and distributing diagnosis keys (backend services / public health workflows).
  • Implements cryptographic protocols and temporary key management aligned with the GAEN specifications (security / cryptography).
  • Offers deployment tooling and configuration to run the backend on cloud infrastructure for regional or national rollouts (cloud deployment / DevOps).

More About LFPH COVID Shield

LFPH COVID Shield addresses the problem of implementing privacy-preserving COVID-19 exposure notification for public health authorities by providing an open-source reference system that integrates with the Google Apple Exposure Notification (GAEN) framework (public health / mobile exposure notification). The project was initially developed for use in government deployments and is now hosted under Linux Foundation Public Health, which maintains a portfolio of open-source projects for public health agencies.

At its core, COVID Shield provides mobile client applications for iOS and Android (mobile applications) that use GAEN APIs on the device to generate and exchange anonymous Bluetooth identifiers. These apps periodically download diagnosis keys from a backend server and perform exposure checks locally on the device, aligning with GAEN’s privacy model (security / privacy-preserving computation). The clients implement user flows for entering one-time codes issued by public health authorities, consenting to share diagnosis keys, and receiving exposure notifications.

The server component of COVID Shield (backend services / microservices) manages registration of one-time codes, acceptance of diagnosis keys from verified users, batching and publishing of keys for download, and rate limiting and auditing functions associated with these workflows. It exposes APIs that the mobile apps call for code validation and for retrieving key files, and it is designed to run on cloud infrastructure with configuration for regional or national deployments. The backend typically runs behind standard web and Application Programming Interface (API) gateways (web services / API management) and integrates with public health operational processes for case management and verification code issuance.

COVID Shield’s architecture follows the GAEN model, in which cryptographic keys are generated and stored on device, and rolling proximity identifiers derived from these keys are broadcast via Bluetooth Low Energy (BLE) (mobile networking / Bluetooth). Exposure risk calculation occurs on the device based on risk parameters supplied via configuration from public health authorities. The backend primarily handles verification and distribution of diagnosis keys and does not store detailed contact graphs, which supports a decentralized, privacy-preserving design (security / privacy-preserving architecture).

Enterprises and institutions, such as governments, public health agencies, and large organizations, can use COVID Shield as a deployable stack or as a reference implementation to understand and implement GAEN-based exposure notification (public health infrastructure). It can be adapted to local regulatory and operational requirements by modifying server configuration, verification flows, and mobile app branding. From a technical taxonomy perspective, COVID Shield fits into public health surveillance infrastructure, mobile exposure notification systems, and privacy-preserving cryptographic protocols in the GAEN ecosystem.