Blockchain-based Covid-19 Certification System

The system has the task of managing Covid-19 certificates, maintaining a list of issuers authorized to issue them, providing the end user with a simple and fast solution for verifying certificates.

System Key Components
The system designed in this thesis consists of:
• a smart contract that runs on the Ethereum network which manages the reading and writing of certificates and authorized issuers;
• an administration platform, which interfaces with the smart contract, accessible only to authorized users, for the creation of new certificates;
• a REST API, for certificate verification, accessible via smartphone application;
• a simple, light and user-friendly smartphone application, suitable for every user.

Firstly, the administration platform verifies the identity of the entity that accesses the system, and if the entity is suitable for access, it allows the generation of new certificates; otherwise, it does not allow access.
The REST API is used to verify existing certificates, it compares the SHA256 hash of the data contained inside the QR Code by the user, with the SHA256 hash saved inside the blockchain. It is freely accessible without authentication, and is meant to be used by the smartphone application.
For the realization of the project, it was decided to use a smart contract on the Ethereum network, written in Solidity. The integrated development environment (IDE) Remix was an effective tool for the development, test- ing and debugging of the smart contract, allowing to greatly speed up the setup phases of the development environment. Remix allows to emulate a blockchain network and a multitude of nodes quickly and easily. Solidity is an object-based language, created specifically to develop smart contracts, especially on Ethereum.