🔐 Zero Knowledge Proof Cryptographic System

Secure Authentication & Integrity Verification Using Zero Knowledge Proofs

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📋 Project Overview

This project demonstrates a practical implementation of Zero Knowledge Proof (ZKP) cryptographic algorithms using a Schnorr-like protocol, applied to real-world security use cases.

The system shows how secrets can be cryptographically proven without ever being transmitted or stored.

Implemented Use Cases

1. Secure Authentication — prove password knowledge without revealing it
2. Digital Forensics — verify file integrity without exposing file contents

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🎯 Problem Statement

Issues with Traditional Authentication

• Passwords are transmitted over networks
• Servers store password hashes that may be leaked
• Man-in-the-middle attacks can capture credentials
• Data breaches expose sensitive secrets

Proposed Solution

Zero Knowledge Proof–based authentication
A cryptographic approach that allows a user to prove knowledge of a secret without ever revealing the secret itself.

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📐 Mathematical Foundation

Schnorr-like Zero Knowledge Proof Protocol

The implementation is based on a Schnorr-style ZKP using the discrete logarithm problem.

Parameters:
- p = 256-bit prime number (secp256k1 prime)
- g = 2 (generator)
- x = secret (derived from password/file hash via SHA-256)
- y = g^x mod p (public value - safe to share)

Protocol Steps:

┌─────────────────┐                    ┌─────────────────┐
│     PROVER      │                    │    VERIFIER     │
│   (Client)      │                    │    (Server)     │
└────────┬────────┘                    └────────┬────────┘
         │                                      │
         │  1. Commitment: t = g^r mod p        │
         │ ────────────────────────────────────>│
         │                                      │
         │  2. Challenge: c (random)            │
         │ <────────────────────────────────────│
         │                                      │
         │  3. Response: s = r + c*x mod (p-1)  │
         │ ────────────────────────────────────>│
         │                                      │
         │  4. Verify: g^s ≟ t * y^c mod p      │
         │                                      │

Why This is Zero Knowledge:

Transmitted (Safe)	Never Transmitted
Commitment (t)	Password
Challenge (c)	Secret (x)
Response (s)	Random nonce (r)
Public value (y)	File contents

Security Basis: Discrete Logarithm Problem - Computing x from y = g^x mod p is computationally infeasible.

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🏗️ Project Architecture

zkp-capstone-final/
│
├── main.py                 # CLI demo runner
├── requirements.txt        # Python dependencies
├── README.md               # This documentation
│
├── authentication/         # Use Case 1: ZKP Authentication
│   ├── __init__.py
│   ├── prover.py          # Prover: generates proofs
│   ├── verifier.py        # Verifier: validates proofs
│   └── auth_flow.py       # Complete auth workflow
│
├── forensics/             # Use Case 2: File Integrity
│   ├── __init__.py
│   ├── prover.py          # Prover: file-based proofs
│   ├── verifier.py        # Verifier: validates file proofs
│   └── file_integrity.py  # Complete file verification flow
│
├── performance/           # Performance Measurement
│   ├── __init__.py
│   ├── metrics.py         # Timing and logging utilities
│   └── results.csv        # Performance data log
│
├── ui/                    # Streamlit Web Interface
│   └── app.py             # Full-featured web UI
│
└── docs/                  # Documentation
    ├── PRESENTATION_GUIDE.md  # How to present the project
    └── ARCHITECTURE.md        # Technical details

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🚀 How to Run

Prerequisites

• Python 3.8 or higher
• pip (Python package manager)

Installation

# 1. Navigate to project folder
cd zkp-capstone-final

# 2. Install dependencies
pip install -r requirements.txt

# 3. Run CLI demo
python main.py

# 4. Run Web Interface (RECOMMENDED for presentation)
streamlit run ui/app.py

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💻 Use Cases

Use Case 1: ZKP Authentication

Scenario: Login to a system without transmitting your password.

Traditional Method (INSECURE):

User → "password123" → Server → Compare with stored hash
❌ Password transmitted
❌ Server sees password

ZKP Method (SECURE):

User → Mathematical Proof → Server → Verify equation
✅ Password NEVER transmitted
✅ Server NEVER sees password
✅ Even if hacked, no passwords leaked

Use Case 2: Digital Forensics File Integrity

Scenario: Prove you have an authentic copy of evidence without sending the file.

Applications:

• Court evidence verification
• Chain of custody in forensics
• Secure backup verification
• Distributed file validation

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📊 Performance Results

Our system demonstrates excellent performance:

Operation	Average Time
Proof Generation	< 1 ms
Verification	< 1 ms
Total Round-trip	< 2 ms

Based on 256-bit prime modular exponentiation

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🔒 Security Properties

1. Completeness

If the prover knows the secret, verification always succeeds.

2. Soundness

If the prover does NOT know the secret, they cannot forge a valid proof (probability ≈ 1/p ≈ 0).

3. Zero Knowledge

The verifier learns NOTHING about the secret from the proof values.

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🛠️ Technology Stack

Component	Technology
Language	Python 3.8+
Cryptography	SHA-256, Modular Arithmetic
Protocol	Schnorr-like ZKP
Web UI	Streamlit
Logging	CSV

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📚 References

1. Schnorr, C.P. (1991). Efficient signature generation by smart cards. Journal of Cryptology
2. Goldwasser, S., Micali, S., & Rackoff, C. (1989). The knowledge complexity of interactive proof systems. SIAM Journal on Computing
3. RFC 8235 - Schnorr Non-interactive Zero-Knowledge Proof

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✅ Features

• Schnorr-like ZKP Protocol
• Secure Password Authentication
• File Integrity Verification
• Command-line Interface (CLI)
• Web-based User Interface (Streamlit)
• Performance Metrics Logging
• Comparative Demo (Traditional vs ZKP)
• Mathematical Visualization

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© 2026 Surya - Zero Knowledge Proof System