Digital Signature Authentication

Digitally signs and verifies files using RSA and SHA-256 to ensure file authenticity, integrity, and tamper detection.

🔐 Digital Signature–Based File Authentication System

Developed by © 2026 Syed Shaheer Hussain

📸 Screenshots

📌 1. Project Description (Overview)

The Digital Signature–Based File Authentication System is a Python-based desktop application designed to ensure file integrity, authenticity, and non-repudiation using modern cryptographic techniques.

This system allows users to digitally sign files using RSA private keys and later verify those files using corresponding public keys or X.509 certificates. Any modification to the file after signing is immediately detected during verification.

This project demonstrates a real-world implementation of cryptography, commonly used in secure communications, legal documents, banking systems, and cybersecurity applications.

🎯 2. Project Objectives

1. Ensure file integrity and tamper detection
2. Authenticate the file owner using cryptographic keys
3. Implement RSA-based digital signatures
4. Support X.509 digital certificates
5. Provide an easy-to-use graphical interface
6. Demonstrate practical cybersecurity concepts
7. Enable secure file exchange and verification

❓ 3. What Is a Digital Signature?

📖 Definition

A digital signature is a cryptographic mechanism that validates the authenticity and integrity of digital data.

🧠 In Simple Terms

A digital signature is like a digital fingerprint and lock attached to a file.

It proves:

• Who signed the file
• That the file was not altered
• That the signer cannot deny signing it

💎 4. Importance & Value of Digital Signatures

• ✔ Data Integrity
• ✔ Authentication
• ✔ Non-Repudiation
• ✔ Legal Validity
• ✔ Cybersecurity Assurance
• ✔ Used in banking, blockchain, government, and legal systems

🧱 5. Technologies Used

🖥️ Programming Language

• Python 3.10+ (Tested on Python 3.14)

🔐 Cryptography

• RSA (2048 / 3072 / 4096 bit)
• SHA-256 Hashing
• PSS Padding
• X.509 Certificates

🎨 GUI Framework

• Tkinter
• ttk Widgets
• TkinterDnD (optional drag & drop)

📦 Libraries / Modules

• cryptography
• hashlib
• base64
• datetime
• tkinter
• tkinterdnd2 (optional)

📦 6. Required Packages (Installation)

pip install cryptography

pip install tkinterdnd2

Tkinter comes pre-installed with Python.

🗂️ 7. Folder Structure

Digital Signature-Based File Authentication/
├── README.md   
├── main.py
├── screenshots/
│   ├── 1.png
│   ├── 2.png
│   ├── 3.png
│   ├── 4.png
│   └── 5.png

🧩 8. System Architecture

🏗️ Architecture Layers

1. GUI Layer (Tkinter)
2. Cryptographic Engine
3. Certificate Engine
4. Audit Logger
5. File System

🔄 9. Code Flow (Execution Flow)

1. Application starts
2. GUI loads
3. User generates or loads RSA keys
4. File is selected
5. File hash (SHA-256) is generated
6. Hash is signed using private key
7. Signature is saved or embedded
8. Verification uses public key
9. Result is displayed
10. Events are logged

🔁 10. Flowchart (Textual Representation)

START
  |
  v
Launch Application
  |
  v
Generate / Load RSA Keys
  |
  v
Select File
  |
  v
Generate SHA-256 Hash
  |
  v
Sign Hash with Private Key
  |
  v
Save / Embed Signature
  |
  v
Verify Using Public Key
  |
  v
Display Result
  |
  v
END

🛠️ 11. How the System Works (Internal Working)

🔐 File Signing Process

1. File is read in binary mode
2. SHA-256 hash is generated
3. Hash is encrypted with private key
4. Signature is saved or embedded

🔎 Verification Process

1. File hash is recalculated
2. Signature is decrypted using public key
3. Hashes are compared
4. Match → Valid
5. Mismatch → Invalid

▶️ 12. Installation Steps

1. Install Python
2. Extract project folder
3. Open terminal in project directory
4. Install required packages
5. Run main.py

▶️ 13. How to Run the Project

python main.py

✔ A GUI window will open.

🧑‍💻 14. How to Use the Application

🔑 Key Management Tab

• Select key size
• Enter optional password
• Generate RSA key pair
• Generate X.509 certificate

✍️ File Signing Tab

• Select private key
• Select file
• Enter password
• Sign file or embed signature

✅ Verification Tab

• Select public key
• Select original file
• Select signature
• Verify authenticity

👁️ Viewer Tab

• View file hash and signature details

⚙️ Settings Tab

• Toggle dark/light mode

⭐ 15. Key Features

• RSA key generation
• X.509 certificate support
• Digital file signing
• Embedded signature support
• Signature verification
• GUI-based interface
• Dark / Light mode
• Audit logging

🧠 16. Major Functions & Modules

• CryptoEngine
• CertificateEngine
• AuditLogger
• DigitalSignatureApp
• SHA-256 hashing
• RSA signing & verification

⚠️ 17. Cautions

Caution

• Do not share private keys
• Losing password makes key unusable
• Modified files will fail verification
• Embedded signatures increase file size

❗ 18. Important Notes

Important

• Designed for educational use
• Production use requires enhancements
• Legal systems require trusted CA certificates

📜 19. Disclaimer

Note

This project is developed for educational and learning purposes only. The developer is not responsible for misuse.

🎓 20. Learning Outcomes

• Cryptography fundamentals
• RSA & hashing algorithms
• Digital certificates
• GUI application design
• Secure file handling
• Cybersecurity principles

🧪 21. Practice Areas

• Cybersecurity
• Digital forensics
• Secure systems
• Ethical hacking
• Python GUI development

🚀 22. Future Enhancements

1. Elliptic Curve Cryptography (ECC)
2. Cloud-based verification
3. Mobile application version
4. Database integration
5. Hardware security modules
6. Verification reports
7. Blockchain anchoring

🔮 23. Future Implementations

• E-Government portals
• Legal documentation systems
• Banking & finance systems
• Software licensing
• Secure email systems

🧾 24. Programming Concepts Used

• Object-Oriented Programming
• Cryptography
• Hashing
• File I/O
• GUI architecture
• Exception handling

👨‍💻 25. Developer Information

© 2026 Syed Shaheer Hussain Digital Signature–Based File Authentication System