A comprehensive Java implementation demonstrating the combination of AES (Advanced Encryption Standard) and RSA encryption algorithms for secure data transmission and digital signatures.

This project provides a complete example of how to combine AES and RSA encryption for secure communication between client and server applications. The implementation includes:

• AES Encryption: Fast symmetric encryption for data payload
• RSA Encryption: Asymmetric encryption for AES key exchange and digital signatures
• Digital Signatures: RSA-based signature generation and verification
• Base64 Encoding: Safe data transmission format

• 🔐 AES-128 Encryption: Fast symmetric encryption for sensitive data
• 🔑 RSA Key Management: Public/private key pair generation and management
• ✍️ Digital Signatures: RSA-based signature generation and verification
• 🔄 Hybrid Encryption: Combines AES speed with RSA security
• 📦 Base64 Encoding: Safe data transmission over text-based protocols
• 🧪 Complete Example: Ready-to-run client-server simulation

The project implements a hybrid encryption scheme:

1. Client Side:

   • Generate random AES key
   • Encrypt data with AES
   • Sign data with RSA private key
   • Encrypt AES key with server's RSA public key

2. Server Side:

   • Decrypt AES key with RSA private key
   • Decrypt data with AES key
   • Verify signature with client's RSA public key

src/main/java/com/wustrive/aesrsa/util/
├── AES.java              # AES encryption/decryption utilities
├── RSA.java              # RSA encryption/decryption and signatures
├── EncryUtil.java        # High-level encryption utilities
├── Base64.java           # Base64 encoding/decoding
├── RandomUtil.java       # Random key generation
├── Digest.java           # Hash and HMAC utilities
├── CheckUtils.java       # Input validation utilities
├── ConvertUtils.java     # Data conversion utilities
└── ConfigureEncryptAndDecrypt.java  # Configuration constants

src/main/java/com/wustrive/
└── Main.java             # Example client-server implementation

• Java 8+
• JUnit 3.8.1 (for testing)
• Log4j 1.2.16 (for logging)
• Apache Commons Lang 2.5 (utility functions)
• FastJSON 1.1.15 (JSON processing)

git clone <repository-url>
cd aes-rsa-java

mvn clean compile

mvn exec:java -Dexec.mainClass="com.wustrive.Main"

// Client side - encrypt and sign data
TreeMap<String, Object> params = new TreeMap<>();
params.put("userid", "152255855");
params.put("phone", "18965621420");

// Generate RSA signature
String sign = EncryUtil.handleRSA(params, clientPrivateKey);
params.put("sign", sign);

// Convert to JSON and encrypt with AES
String info = JSON.toJSONString(params);
String aesKey = RandomUtil.getRandom(16);
String encryptedData = AES.encryptToBase64(info, aesKey);

// Encrypt AES key with server's public key
String encryptedKey = RSA.encrypt(aesKey, serverPublicKey);

// Server side - decrypt and verify
boolean isValid = EncryUtil.checkDecryptAndSign(
    encryptedData, encryptedKey, clientPublicKey, serverPrivateKey);

if (isValid) {
    // Decrypt and process data
    String aesKey = RSA.decrypt(encryptedKey, serverPrivateKey);
    String decryptedData = AES.decryptFromBase64(encryptedData, aesKey);
    // Process decrypted data...
}

• Algorithm: AES-128
• Mode: Default Java Cipher mode
• Key Length: 128 bits (16 bytes)
• Encoding: UTF-8

• Key Size: 1024 bits
• Algorithm: RSA
• Padding: Default Java RSA padding
• Signature: SHA1WithRSA

1. Key Management: Store private keys securely
2. Random Generation: Uses SecureRandom for key generation
3. Input Validation: Comprehensive parameter checking
4. Error Handling: Proper exception handling and logging

• encrypt(byte[] data, byte[] key): Encrypt data with AES
• decrypt(byte[] data, byte[] key): Decrypt data with AES
• encryptToBase64(String data, String key): Encrypt string to Base64
• decryptFromBase64(String data, String key): Decrypt Base64 string

• generateKeyPair(): Generate RSA key pair
• encrypt(String data, String publicKey): Encrypt with RSA
• decrypt(String data, String privateKey): Decrypt with RSA
• sign(String content, String privateKey): Create digital signature
• checkSign(String content, String sign, String publicKey): Verify signature

• handleRSA(TreeMap<String, Object> map, String privateKey): Generate signature
• checkDecryptAndSign(...): Complete decryption and verification process

Run the test suite:

mvn test

This project is licensed under the MIT License - see the LICENSE file for details.

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

⚠️ Important: This is an educational example. For production use:

• Use longer RSA key sizes (2048+ bits)
• Implement proper key rotation
• Use secure random number generation
• Follow security best practices for key storage
• Consider using established cryptographic libraries

Created by wustrive - demonstrating AES+RSA hybrid encryption in Java.