To simulate a Birthday Attack using OMNeT++, which is challenging, as OMNeT++ mainly concentrates on network simulations instead of cryptographic operations. But, we can be mimicked a network-based birthday attack by making scenarios in which the attacker exploits hash collisions within a network environment, particularly for protocols depending on cryptographic hash functions for integrity or authentication. The attacker attempts to discover the hash collisions by using the birthday paradox to bypass security mechanisms.
Below is a brief approach on how to simulate the Birthday Attack Projects in OMNeT++:
Key Concepts for a Birthday Attack in OMNeT++
A birthday attack includes discovering two distinct inputs, which produce the similar hash value (collision). For instance:
- In digital signatures, a malicious node may discover two distinct messages with the similar hash and then utilize the forged message to deceive the recipient.
- In message authentication codes (MACs), the attacker might discover collisions to bypass security checks.
Here, we simulate a basic birthday attack in which the attacker attempts to discover hash collisions and bypass an integrity-checking mechanism in a network.
Step-by-Step Guide to Simulate a Birthday Attack in OMNeT++
- Install OMNeT++ and INET Framework
- Install OMNeT++ from here.
- Install the INET framework from INET GitHub repository. INET framework delivers support for network communication protocols such as TCP, UDP, and HTTP, and it can be mimicked secure communication and attacks.
- Network Scenario
We make a network in which legitimate nodes are communicate securely, exploiting hash-based message integrity (e.g., using SHA-1 or MD5). The attacker node attempts to discover a hash collision and use it to bypass the integrity checks and change messages or authentication.
- Network Topology in NED
Descover the network in which legitimate nodes are transmit hashed messages, and the attacker node attempts to discover a collision to deceive the recipient.
Example NED File for Birthday Attack:
network BirthdayAttackNetwork {
submodules:
client: StandardHost {
@display(“p=100,200”);
}
server: StandardHost {
@display(“p=300,200”);
}
attacker: StandardHost {
@display(“p=200,250”);
}
router: Router {
@display(“p=200,150”);
}
connections allowunconnected:
client.ethg++ <–> Eth100M <–> router.ethg++;
server.ethg++ <–> Eth100M <–> router.ethg++;
attacker.ethg++ <–> Eth100M <–> router.ethg++; // Attacker node connected to the same network
}
- Configure Secure Communication Using Hashes
In this sample, we can replicate secure communication among the client and the server, in which the client transmits messages to the server together with the hash of the message for integrity verification.
Example omnetpp.ini Configuration:
[General]
network = BirthdayAttackNetwork
sim-time-limit = 100s
# Server configuration (listening on TCP port 80, verifying message integrity)
**.server.numApps = 1
**.server.app[0].typename = “TcpServerApp”
**.server.app[0].localPort = 80
# Client configuration (sending hashed messages)
**.client.numApps = 1
**.client.app[0].typename = “TcpApp”
**.client.app[0].connectAddress = “server”
**.client.app[0].connectPort = 80
**.client.app[0].message = “SecureMessage”
**.client.app[0].sendInterval = 1s
**.client.app[0].hashFunction = “SHA-1” # Hash function used for integrity checks
# Attacker configuration (performing a birthday attack)
**.attacker.numApps = 1
**.attacker.app[0].typename = “BirthdayAttackApp”
In this configuration:
- The client transmits a secure message together with its SHA-1 hash to the server.
- The server verifies if the received message’s hash matches the computed hash to make sure message integrity.
- The attacker attempts to discover collisions by generating distinct messages, which produce the similar hash as the legitimate message.
- Implement the Birthday Attack
The attacker node tries to generate several inputs and hash them. The attacker is attempting to discover distinct inputs, which generate the similar hash (collision). When a collision is discovered then the attacker transmits the forged message to the server, bypassing the integrity check.
Example C++ Code for BirthdayAttackApp:
#include “inet/applications/base/ApplicationBase.h”
#include “inet/common/packet/Packet.h”
#include <openssl/sha.h> // Use OpenSSL for hashing
class BirthdayAttackApp : public inet::ApplicationBase {
protected:
virtual void initialize(int stage) override;
virtual void handleMessage(cMessage *msg) override;
virtual std::string generateRandomInput();
virtual std::string hashInput(const std::string &input);
virtual void performBirthdayAttack();
public:
BirthdayAttackApp() {}
virtual ~BirthdayAttackApp() {}
};
Define_Module(BirthdayAttackApp);
void BirthdayAttackApp::initialize(int stage) {
if (stage == inet::INITSTAGE_APPLICATION_LAYER) {
// Start the attack after 1 second
scheduleAt(simTime() + 1.0, new cMessage(“startAttack”));
}
}
void BirthdayAttackApp::handleMessage(cMessage *msg) {
if (strcmp(msg->getName(), “startAttack”) == 0) {
performBirthdayAttack();
}
delete msg;
}
std::string BirthdayAttackApp::generateRandomInput() {
// Generate random input (forged message)
char randomInput[20];
snprintf(randomInput, sizeof(randomInput), “Data-%d”, rand());
return std::string(randomInput);
}
std::string BirthdayAttackApp::hashInput(const std::string &input) {
// Hash the input using SHA-1
unsigned char hash[SHA_DIGEST_LENGTH];
SHA1(reinterpret_cast<const unsigned char *>(input.c_str()), input.length(), hash);
// Convert the hash to hexadecimal format
char hexHash[SHA_DIGEST_LENGTH * 2 + 1];
for (int i = 0; i < SHA_DIGEST_LENGTH; ++i) {
snprintf(hexHash + i * 2, sizeof(hexHash) – i * 2, “%02x”, hash[i]);
}
return std::string(hexHash);
}
void BirthdayAttackApp::performBirthdayAttack() {
std::map<std::string, std::string> hashTable;
bool collisionFound = false;
while (!collisionFound) {
std::string input = generateRandomInput();
std::string hashValue = hashInput(input);
// Check if this hash value already exists in the table
if (hashTable.find(hashValue) != hashTable.end()) {
EV << “Collision found! Input 1: ” << hashTable[hashValue] << “, Input 2: ” << input << endl;
collisionFound = true;
} else {
// Store the hash and input in the table
hashTable[hashValue] = input;
}
}
}
In this code:
- BirthdayAttackApp makes random inputs and hashes them using SHA-1.
- The attacker stores the hash values in a table and searches for a collision.
- When a collision is discovered then the attacker logs the two inputs, which produce the similar hash.
- Monitor and Capture Traffic
Allow packet capture to monitor the network traffic and examine how the attack influences the communication.
Enable Packet Capture in omnetpp.ini:
# Enable packet capture to analyze the birthday attack
**.pcapRecorder.enable = true
**.pcapRecorder.packetFilter = “all”
**.pcapRecorder.file = “output/birthday_attack.pcap”
- Run the Simulation
We can run the simulation in OMNeT++ to monitor how the attacker generates collisions and tries to bypass the server’s integrity checks. The client transmits legitimate messages, even though the attacker tries to forge messages by discovering hash collisions.
- Analyze Results
- Collision Detection: Verify if the attacker discovered a collision (two different inputs with the same hash) and exploited it.
- Packet Integrity: Investigate the integrity of packets using Wireshark to observe if the attacker bypassed the server’s integrity check.
- Effectiveness of the Attack: Calculate how long it took the attacker to discover a collision and whether the attack was effective.
- Extend the Simulation
We can expand the birthday attack simulation by inserting the following aspects:
- Different Hash Functions: Experiment diverse hash functions such as MD5, SHA-256, and also monitor how they perform versus birthday attacks.
- Attack Variants: Replicate attacks on digital signatures, certificates, or message authentication codes (MACs) by exploiting hash collisions.
- Defense Mechanisms: Execute countermeasures like switching to cryptographically secure hash functions and check the efficiency of these defenses.
Example Projects for Birthday Attack Simulation:
- Simple Hash Collision: Mimic a birthday attack on a basic message integrity system and exploit hash collisions to forge messages.
- Digital Signature Attack: Replicate a birthday attack to break digital signatures by discovering two messages with the similar signature.
- Certificate Forgery: Mimic a birthday attack to forge a certificate by using a hash collision.
- Hash Function Comparison: Compare the performance of distinct hash functions (MD5, SHA-1, SHA-256) versus birthday attacks and compute the time to discover collisions.
- Birthday Attack with Defense: Replicate an attack on a network with stronger hash functions (e.g., SHA-256) and experiment the resilience versus the birthday attack.
We displayed the necessary technique to execute and simulate the Birthday Attack projects, where the attacker tries to find hash collisions and bypass an integrity-checking mechanism in a network using OMNeT++. More informations will be followed, if required. All the Concepts for a Birthday Attack in OMNeT++ tool are worked by our developers, so stay in touch with us to get novel topic guidance.
