client

IS/Lab/Eval-Endsem/q.md

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+# Question
+
+**Design and implement a privacy-preserving medical records management system with the following requirements:**
+
+1. **System Architecture**: Create a client-server architecture where:
+   - Doctors (clients) can register, submit medical reports, and log expenses
+   - An auditor can verify reports and perform aggregate analysis without decrypting individual records
+
+2. **Cryptographic Requirements**:
+   - Use **RSA** for encrypting sensitive AES keys during report transmission
+   - Use **ElGamal** for digitally signing reports with timestamps
+   - Use **Paillier homomorphic encryption** for department information to enable privacy-preserving keyword searches
+   - Use **RSA-based homomorphic encryption** (exponent trick) to allow summation of encrypted expenses without decryption
+   - Use **AES-256** for authenticated encryption of report contents
+
+3. **Functional Features**:
+   - Doctor registration with encrypted department information
+   - Secure report submission with signature verification
+   - Privacy-preserving expense tracking where individual amounts remain encrypted
+   - Auditor capabilities to:
+     - Search doctors by department keyword without decrypting data
+     - Sum all expenses across doctors or per-doctor while maintaining encryption
+     - Verify report authenticity and timestamps
+     - List and audit all stored records
+
+4. **Implementation Details**:
+   - Implement server-side state management with persistent JSON storage
+   - Implement client-side key generation and cryptographic operations
+   - Use socket-based TCP communication with JSON serialization
+   - Handle concurrent connections with thread-safe operations
+   - Support multiple independent doctor clients connecting to a single server
+
+**Required**: Provide both server and client implementations with proper key management, error handling, and an interactive menu system for all user roles.
+
+# Answers
+
+Client - [Code](https://git.aadit.cc/aadit/MIT-Curricular/src/branch/main/IS/Lab/Eval-Endsem/client.py)
+Server - [Server](https://git.aadit.cc/aadit/MIT-Curricular/src/branch/main/IS/Lab/Eval-Endsem/server.py)