CipherForge: Modular Encryption Suite

CipherForge is a modular encryption and decryption platform built in Java using JavaFX. It demonstrates strong object-oriented design principles, a clean separation of concerns and an extensible architecture for implementing multiple encryption algorithms.

---

Overview

CipherForge is designed as a pluggable encryption framework that allows users to encrypt and decrypt text and files using different algorithms through a graphical interface.

The project focuses on:

• Object-Oriented Programming principles
• Strategy Design Pattern
• Modular and scalable architecture
• Separation of UI and business logic
• Desktop application development using JavaFX

---

Feature Status

Feature	Status
EncryptionStrategy interface	✅ Done
CaesarStrategy	✅ Done
AESStrategy (CBC mode)	✅ Done
FileEncryptionUtil	✅ Done
EncryptionContext	✅ Done
FileHandler	✅ Done
EncryptionException	✅ Done
InvalidKeyException	✅ Done
JavaFX UI (FXML + CSS)	✅ Done
MainApp entry point	✅ Done
UML Diagrams	✅ Done

---

Project Architecture

                        MainApp.java
                             │
                       ConsoleUI.java
                             │
                   EncryptionContext.java
                             │
               ┌─────────────┴─────────────┐
               │                           │
        AESStrategy                 CaesarStrategy
               │
        FileEncryptionUtil
                             │
                    EncryptionStrategy
                        (interface)
                             │
              ┌──────────────┴──────────────┐
              │                             │
      EncryptionException          InvalidKeyException

---

OOP Concepts Covered

Concept	Where
Encapsulation	Private fields with controlled access throughout
Abstraction	EncryptionStrategy interface
Inheritance	AESStrategy, CaesarStrategy implement interface
Polymorphism	encrypt(), decrypt() behave differently per class
Composition	EncryptionContext has-a EncryptionStrategy
Method Overriding	Each strategy overrides interface methods
Exception Handling	EncryptionException, InvalidKeyException
Packages	Modular structure across crypto, context, util
Design Pattern	Strategy Pattern

---

Folder Structure

src/
├── crypto/
│    ├── EncryptionStrategy.java    ← Strategy interface
│    ├── CaesarStrategy.java        ← Caesar Cipher
│    ├── AESStrategy.java           ← AES-128 CBC
│    └── FileEncryptionUtil.java    ← File encryption via AES
├── context/
│    └── EncryptionContext.java     ← Strategy selector
├── util/
│    └── FileHandler.java           ← File read/write
├── exceptions/
│    ├── EncryptionException.java
│    └── InvalidKeyException.java
├── ui/
│    ├── fxml/                      ← Layout files
│    ├── css/                       ← Styling
│    └── controllers/               ← UI controllers
└── MainApp.java                    ← Entry point

---

Encryption Algorithms

Caesar Cipher

Shifts each character by a numeric key value.

Input  : "HELLO", key = 3
Output : "KHOOR"

Simple substitution cipher used for testing system flow.

AES-128 (Advanced Encryption Standard)

Industry-standard symmetric block cipher using Java Cryptography API.

Property	Value
Mode	CBC (Cipher Block Chaining)
Key	Any string → SHA-256 → 16 bytes
IV	Random 16 bytes per encryption
Output	Base64 encoded string
Block Size	16 bytes
Rounds	10

File Encryption

Encrypts any file type using AES internally.

Operation	Flow
Encrypt	file bytes → Base64 → AES encrypt → .encrypted
Decrypt	.encrypted → AES decrypt → Base64 → original file

---

Security Design Decisions

Decision	Reason
CBC mode instead of ECB	ECB leaks patterns - identical blocks produce identical ciphertext. CBC chains each block to the previous output.
SHA-256 key derivation	AES needs exactly 16 bytes. SHA-256 converts any password to a fixed output. Zero-padding is guessable.
SecureRandom for IV	Regular Random is predictable if seed is known. SecureRandom uses hardware entropy, truly unpredictable.
IV prepended to output	Decryptor needs same IV. Stored as first 16 bytes of output.
Base64 encoding	Raw bytes corrupt in String form. Base64 is safe and printable.

---

Error Handling

Error	Handled By
Invalid key format	InvalidKeyException
Null strategy	EncryptionException
File read/write errors	FileHandler + exceptions
AES key length issues	buildKey() via SHA-256

---

System Flow

User Input → MainApp → EncryptionContext → Strategy → Output

1. User selects algorithm (AES / Caesar)
2. User provides input data and key
3. Context sets the chosen strategy
4. Strategy performs encryption or decryption
5. Result is displayed to the user

---

How to Run

🚧 Full setup instructions will be added once the project compiles end-to-end.

Requirements: JDK 17+, JavaFX SDK. No external dependencies.

# Clone the repository
git clone https://github.com/tanushrijadhav/encryption-decryption-oopd-java.git
cd encryption-decryption-oopd-java

# Run the batch file
run.bat

---

Team Contribution

Member	Responsibility	Modules
Tanushri Jadhav	Crypto logic - Caesar, AES, interface	crypto/
Tanushka Gulhane	Context, File Handling, Exceptions	context/, util/, exceptions/
Advait Gajewar	MainApp, UI, Integration	ui/, MainApp.java

---

Learning Outcomes

• Practical implementation of OOP concepts
• Understanding of the Strategy Design Pattern
• Hands-on experience with Java Cryptography API
• Modular software design
• Team collaboration using GitHub

---

License

This project is for educational and demonstration purposes.

---

OOPD Mini Project