SSCP Systems Security Certified PractitionerCryptographyHard
A cryptocurrency project aims to use a hashing algorithm that is resistant to quantum computing attacks. Which of the following hashing algorithms is currently considered to offer post-quantum security properties?
- ASHA-256
- BLamport one-time signature scheme
- CMD5
- DShor's algorithm
Show answer & explanationAnswer & explanation
Correct answer: B. Lamport one-time signature scheme
SHA-256 and MD5 are classical hash functions not specifically designed for post-quantum resistance, though generic hash functions are generally more quantum-resistant than asymmetric algorithms. Shor's algorithm is a quantum algorithm that breaks RSA/ECC, not a hashing algorithm. The Lamport one-time signature scheme is a specific construction that uses hash functions in a way that provides quantum resistance, demonstrating a post-quantum cryptographic primitive.
Why the other options are wrong
- A. SHA-256 is a widely used hash function, but while generic hash functions are considered relatively quantum-resistant (requiring more quantum operations than classical), it's not explicitly 'post-quantum' in the same way as specialized schemes.
- C. MD5 is cryptographically broken and highly insecure, completely unsuitable for any modern security application, let alone post-quantum.
- D. Shor's algorithm is a quantum algorithm that can break RSA and ECC, not a hashing algorithm or a post-quantum cryptographic solution.
Post-Quantum Cryptography (PQC)
Cryptographic algorithms that are secure against attacks by quantum computers, as well as classical computers.
- Focuses on replacing asymmetric algorithms (RSA, ECC) first.
- Hash-based signatures (like Lamport) are a promising PQC area.
- NIST is standardizing PQC algorithms.
Memory trick: Quantum computers break old locks; we need new hash-based keys, like Lamport's one-time magic.