EHR Blockchain Simulation

Overview

This project implements a blockchain-based Electronic Health Record (EHR) system with secure data storage and access control. The system integrates blockchain technology with AES encryption to protect sensitive patient information.

Key Features

• Secure Data Storage: Patient and visit records are encrypted using AES Symmetric key algorithm
• Access Control: Patients can only view their own data; doctors can access patient records with appropriate permissions
• Blockchain Integrity: All records are stored on an immutable blockchain with proof-of-work validation
• Fast Retrieval: Optimized search using hash-based indexing for quick data access

System Architecture

Core Components

• Doctors: Create and manage patient records, add visit information
• Patients: Store health data encrypted on the blockchain
• Patient Visits: Track medical appointments and clinical observations
• Admin: Manage doctors in the system

Data Encryption

Both patient records and visit information are encrypted using AES algorithms where the EHR system maintains the encryption keys.

Process Flow

User Management

• The system initializes with at least one predefined doctor
• Admins can add new doctors to the system
• Doctors can register and manage patients

Patient Registration

When creating a patient record, the following information is collected:

• Name, Age, Height, Weight, Sex
• Initial vital signs (Blood Pressure, Oxygen Level, Glucose Level)

The patient data is converted to a string representation, encrypted, and stored on the blockchain.

Patient Visits

Doctors can record patient visit information including:

• Patient index reference
• Vital signs (Pulse, Oxygen Level, Blood Pressure, Glucose Level, Temperature)
• Diagnosis and reason for visit
• Prescribed treatment

Visit data follows the same encryption and blockchain storage process as patient records.

Data Retrieval

• Doctors can access any patient's complete medical history
• Records are indexed using a hash map with keys formatted as:
  • p_x: Patient record (where x is the patient index)
  • v_x: Visit records (where x is the patient index)

Blockchain Implementation

Block Structure

Each block contains:

• Encrypted content data
• Previous block hash
• Current block hash
• Nonce value for proof-of-work

Mining Process

1. The system calculates an appropriate nonce value
2. Generates a hash with a configurable number of leading zeros (set to 4 in this implementation)
3. Stores the nonce and hash in the block

Validation

After each block insertion, a validity checker:

• Recalculates hashes for the entire blockchain
• Verifies chain integrity to detect any corruption or unauthorized modifications