SecureLink

A network encryption library implementing AES-256-GCM and ChaCha20-Poly1305 with advanced security features for secure communication protocols.

⚠️ Security Notice

This library contains implementation bugs and is not production-ready. Use only for research, educational purposes, or as a foundation requiring thorough security review. Key exchange protocols must be implemented separately.

Features

• Multiple Cipher Support: AES-256-GCM and ChaCha20-Poly1305 AEAD encryption
• Forward Secrecy: Automatic key rotation every 100 packets
• Replay Protection: Sliding window anti-replay mechanism
• Secure Memory: Memory locking, secure allocation, and explicit clearing
• Message Fragmentation: Automatic handling of large messages
• Traffic Obfuscation: Padding-based traffic analysis resistance
• Thread Safety: Full multi-threaded operation support
• Session Management: Multiple concurrent encrypted sessions

Requirements

• libsodium - Modern cryptographic library
• OpenSSL - Cryptographic functions and key derivation
• pthread - Thread synchronization
• GCC with C99 support

Installation

# Install dependencies (Ubuntu/Debian)
sudo apt-get install libsodium-dev libssl-dev

# Compile
gcc -O2 -Wall -Wextra -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fPIE -pie securelink.c -lcrypto -lsodium -pthread -o securelink

Quick Start

#include "securelink.h"

int main() {
    // Initialize cryptographic subsystem
    crypto_init();
    
    // Create session manager
    uint8_t master_secret[32];
    secure_random(master_secret, 32);
    session_manager_t *mgr = session_manager_create(master_secret);
    
    // Establish secure session
    uint8_t ephemeral_key[32];
    secure_random(ephemeral_key, 32);
    crypto_context_t *session = establish_session(mgr, 
        (uint8_t*)"peer_id", 7, ephemeral_key, CIPHER_AES_256_GCM);
    
    // Encrypt data
    const char *message = "Sensitive data requiring encryption";
    uint8_t *encrypted;
    size_t encrypted_len;
    
    encrypt_packet(session, (uint8_t*)message, strlen(message), 
                  &encrypted, &encrypted_len);
    
    // Decrypt data
    uint8_t *decrypted;
    size_t decrypted_len;
    
    decrypt_packet(session, encrypted, encrypted_len, 
                  &decrypted, &decrypted_len);
    
    printf("Decrypted: %.*s\n", (int)decrypted_len, decrypted);
    
    // Cleanup
    free(encrypted);
    free(decrypted);
    close_session(mgr, session);
    session_manager_free(mgr);
    
    return 0;
}

Architecture

┌─────────────────┐    ┌─────────────────┐
│  Session Mgr    │    │  Crypto Context │
│                 │    │                 │
│ ┌─────────────┐ │    │ ┌─────────────┐ │
│ │   Session   │ │    │ │  AES-GCM    │ │
│ │ Management  │ │────│ │ ChaCha20    │ │
│ └─────────────┘ │    │ └─────────────┘ │
│                 │    │                 │
│ ┌─────────────┐ │    │ ┌─────────────┐ │
│ │  Key Store  │ │    │ │   Replay    │ │
│ │   (Secure)  │ │────│ │ Protection  │ │
│ └─────────────┘ │    │ └─────────────┘ │
└─────────────────┘    └─────────────────┘
         │                        │
         └────────────────────────┘
                    │
         ┌─────────────────┐
         │  Network Layer  │
         │ (Not Included)  │
         └─────────────────┘

API Reference

Core Functions

• crypto_init() - Initialize cryptographic libraries
• session_manager_create() - Create session manager
• establish_session() - Create encrypted session
• encrypt_packet() - Encrypt data packet
• decrypt_packet() - Decrypt data packet
• close_session() - Terminate session
• session_manager_free() - Cleanup manager

Advanced Features

• send_fragmented() - Fragment large messages
• receive_fragmented() - Reassemble fragments
• obfuscate_packet() - Add traffic padding
• deobfuscate_packet() - Remove padding

Testing

# Run built-in test suite
./securelink

# Expected output includes performance metrics
# Throughput: ~XXX MB/s depending on hardware

Use Cases

• Custom VPN implementations
• Secure file transfer protocols
• IoT device communication
• P2P encrypted messaging
• Research and education
• Protocol development

Security Considerations

Current Limitations

• No key exchange protocol - Requires pre-shared secrets
• Implementation bugs - Needs security audit
• Missing peer authentication - No identity verification
• No perfect forward secrecy - Key rotation only

Recommendations

• Implement proper key exchange (ECDH, X25519)
• Add mutual authentication
• Conduct thorough security review
• Implement proper protocol state machines
• Add comprehensive fuzzing tests

Performance

Typical performance on modern hardware:

• AES-256-GCM: ~200-400 MB/s
• ChaCha20-Poly1305: ~150-300 MB/s
• Memory overhead: ~2KB per session
• Key rotation: Automatic every 100 packets

Disclaimer

This software is provided for educational and research purposes. The authors are not responsible for any misuse or security vulnerabilities. Professional security review is required before production deployment.

---

SecureLink - Emphasizes secure communication links while remaining professional and descriptive.