Java-AES

AES File Encryption and Decryption in Java

This project provides Java classes for encrypting and decrypting files using AES (Advanced Encryption Standard) with a 256-bit key. It includes two main components:

• Encrypt.java: Encrypts files with AES encryption.
• Decrypt.java: Decrypts files that were encrypted with Encrypt.java.

Features

• AES Encryption: Uses a 256-bit AES key with CBC (Cipher Block Chaining) mode.
• Key Padding: Automatically pads keys shorter than 256 bits with random bytes in Encrypt.java and with a provided padding in Decrypt.java.
• File-based Encryption: Encrypts and decrypts files with added IV (Initialization Vector) support for secure encryption.

Prerequisites

• Java Development Kit (JDK) 8 or above.
• AES-256 Support: Ensure the JRE/JDK supports AES-256. For some environments, you may need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files.

Usage

0. Jar File Download

releases-latest
Windows Version

1. Compile the Java files

javac Encrypt.java
javac Decrypt.java

2. Run the Encryption

Use Encrypt to encrypt a file by specifying the file path and encryption key.

java Encrypt

3. Run the Decryption

Use Decrypt to decrypt a file by specifying the encrypted file path and the decryption key.

java Decrypt 

Code Details

Encrypt.java

• padKey(byte[] key): Pads the encryption key to a length of 256 bits (32 bytes) with random bytes if the provided key is shorter.
• encryptFile(String inputFile, byte[] key): Encrypts the specified file using AES and saves the result to an output file.

Decrypt.java

• padKey(byte[] key, byte[] padding): Reconstructs the original padded key used for encryption by combining the provided key with the padding.
• decryptFile(String inputFile, byte[] key): Decrypts the specified encrypted file and saves the original content to an output file.

Notes

• Both encryption and decryption require that the key used in decryption exactly matches the key (including padding) used in encryption.
• The Encrypt.java class saves the IV at the beginning of the encrypted file, which Decrypt.java reads to ensure secure decryption.

License

This project is open-source and available under the MIT License.

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