README.md

🔒 Secure File Transfer (Hybrid AES + RSA)

This Java project provides secure file encryption and decryption using a hybrid AES + RSA system.

📝 Overview

• Main.java
  Handles both encryption and decryption automatically.

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🛡️ Encryptor

• Encrypts all files in the input folder using a generated AES key.
• Encrypts the AES key with the Client’s public RSA key.
• Computes a SHA-256 hash of the encrypted AES key for integrity verification.
• Stores the following in the encrypted folder:
  • AES-encrypted files (.enc)
  • Encrypted AES keys (.key.enc)
  • SHA-256 hash of AES keys (.key.sha256)
• Deletes the original files from input after successful encryption. ✅

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🔑 Decryptor

• Uses the User’s private RSA key to decrypt AES keys.
• Verifies AES key integrity using the stored SHA-256 hash.
• Decrypts the encrypted files using the decrypted AES key.
• Outputs the decrypted files to the output folder.
• Deletes the encrypted files after successful decryption. ✅

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📂 Folder Structure

SecureFileTransfer/

├── input/ # 📥 Files to encrypt

├── encrypted/ # 🔒 Encrypted files, keys, and hashes

├── output/ # 📤 Decrypted output files

├── keys/

│ ├── User/ # 🧑‍💻 User private key

│ └── Client/ # 👤 Client public key

├── Main.java # 🏃 Handles encryption and decryption

├── Encryptor.java # ✨ Optional separate encryptor

└── Decryptor.java # ✨ Optional separate decryptor

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🚀 Usage

1. Place files you want to encrypt in the input/ folder. 📥
2. Ensure the keys are correctly placed in keys/User and keys/Client. 🔑
3. Run Main.java — it will automatically detect and:
   • Encrypt files if input/ contains files
   • Decrypt files if encrypted/ contains files
4. Check the encrypted/ or output/ folders for results. 📂
5. Original files are deleted automatically after successful operations. 🗑️

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Note: The project uses AES for file encryption and RSA for secure AES key exchange, with SHA-256 hash for integrity verification.