Quantum-resistant encryption refers to cryptographic methods designed to secure data against the potential threats posed by quantum computing. As quantum computers become more powerful, traditional encryption methods may become vulnerable, making quantum-resistant techniques essential for future security.
These cryptographic systems rely on mathematical problems that are believed to be difficult for both classical and quantum computers to solve, ensuring data remains secure in a post-quantum world.
Encrypted data is collected and stored
Quantum computers achieve cryptographic relevance
Previously secure data is compromised
The importance of quantum-resistant encryption lies in its ability to protect sensitive information from being decrypted by quantum computers. This is crucial for maintaining the confidentiality and integrity of data in various applications, including financial transactions, personal communications, and sensitive government information.
Several approaches to quantum-resistant cryptography have emerged, each with different mathematical foundations and security properties:
Based on the hardness of finding closest vectors in high-dimensional lattices
Uses cryptographic hash functions to create one-time or few-time signatures
Based on the difficulty of solving systems of multivariate polynomial equations
Lattice-based cryptography is one of the most promising approaches for post-quantum security. NIST has selected multiple lattice-based algorithms as part of its post-quantum cryptography standardization process.
// Example of a simple lattice-based encryption scheme (pseudocode)
function encrypt(message, publicKey) {
// Generate a random polynomial
polynomial r = randomPolynomial();
// Encrypt the message using the public key and the random polynomial
return (message + publicKey * r) % q;
}
function decrypt(ciphertext, privateKey) {
// Decrypt the ciphertext using the private key
return (ciphertext - privateKey) % q;
}This pseudocode illustrates a basic lattice-based encryption scheme, where a message is encrypted using a public key and a random polynomial. The decryption process uses the private key to retrieve the original message.
Implementing quantum-resistant encryption often involves integrating established libraries and following emerging standards. As these algorithms are still being standardized, implementations need to be adaptable:
// Example Node.js implementation using Open Quantum Safe library wrapper
const crypto = require('crypto');
const oqs = require('node-oqs');
// Create a post-quantum key encapsulation mechanism (KEM)
function demonstrateKyber() {
try {
// Initialize Kyber-512 KEM (NIST Round 3 selection)
const kyber = new oqs.KeyEncapsulation('Kyber512');
// Generate key pair
const keys = kyber.keypair();
console.log('Public key length:', keys.public_key.length, 'bytes');
// Encapsulate - generates a shared secret and ciphertext
const encapsulation = kyber.encapsulate(keys.public_key);
console.log('Ciphertext length:', encapsulation.ciphertext.length, 'bytes');
console.log('Shared secret length:', encapsulation.shared_secret.length, 'bytes');
// Decapsulate - recovers the shared secret from ciphertext
const decapsulated = kyber.decapsulate(encapsulation.ciphertext, keys.secret_key);
// Verify that both parties have the same shared secret
console.log('Shared secrets match:',
Buffer.compare(encapsulation.shared_secret, decapsulated) === 0);
// Clean up
kyber.free();
return {
publicKeySize: keys.public_key.length,
secretKeySize: keys.secret_key.length,
ciphertextSize: encapsulation.ciphertext.length,
sharedSecretSize: encapsulation.shared_secret.length
};
} catch (err) {
console.error('Error in Kyber demonstration:', err);
}
}
// Example hybrid implementation combining traditional and PQ crypto
function hybridEncrypt(plaintext, recipientRSAPublicKey, kemAlgorithm = 'Kyber512') {
// 1. Generate a random AES key
const aesKey = crypto.randomBytes(32);
// 2. Encrypt the plaintext with AES
const iv = crypto.randomBytes(16);
const cipher = crypto.createCipheriv('aes-256-gcm', aesKey, iv);
let encrypted = cipher.update(plaintext, 'utf8', 'hex');
encrypted += cipher.final('hex');
const authTag = cipher.getAuthTag();
// 3. Encrypt the AES key with traditional RSA
const rsaEncryptedKey = crypto.publicEncrypt(
recipientRSAPublicKey,
aesKey
);
// 4. Also encrypt the AES key with post-quantum KEM
const kem = new oqs.KeyEncapsulation(kemAlgorithm);
const recipientKEMPublicKey = getRecipientKEMPublicKey(); // Get from key server
const kemEncapsulation = kem.encapsulate(recipientKEMPublicKey);
// 5. Return the complete hybrid encrypted package
return {
iv: iv.toString('hex'),
authTag: authTag.toString('hex'),
encryptedData: encrypted,
rsaEncryptedKey: rsaEncryptedKey.toString('hex'),
kemCiphertext: kemEncapsulation.ciphertext.toString('hex'),
algorithm: kemAlgorithm
};
}This code demonstrates a hybrid approach using both traditional RSA encryption and a post-quantum KEM (Kyber) to encrypt data. This provides immediate protection against quantum attacks while maintaining compatibility with existing systems.
Each quantum-resistant approach offers different trade-offs in terms of key size, signature/ciphertext size, and computational requirements:
| Algorithm Type | Key Size | Performance | NIST Status | Confidence |
|---|---|---|---|---|
| Lattice-Based | Medium | High | Selected (Kyber) | High |
| Hash-Based | Small | Medium | Selected (SPHINCS+) | Very High |
| Multivariate | Very Large | Low | Not Selected | Medium |
| Code-Based | Large | Medium | Selected (Classic McEliece) | High |