SSCP Systems Security Certified PractitionerCryptographyMedium
A cryptocurrency project aims to use a hashing algorithm that is resistant to quantum computing attacks. Which of the following properties is MOST crucial for a hashing algorithm to be considered 'quantum-resistant'?
- ACollision resistance for classical computers
- BResistance to Shor's algorithm
- CResistance to Grover's algorithm
- DPre-image resistance for classical computers
Show answer & explanationAnswer & explanation
Correct answer: C. Resistance to Grover's algorithm
Grover's algorithm significantly reduces the time required for brute-force attacks on hash functions. Therefore, a quantum-resistant hash must have a much larger output size (e.g., 256 bits for SHA-256 might effectively become 128 bits against Grover's) to maintain adequate security against quantum adversaries.
Why the other options are wrong
- A. Collision resistance for classical computers is a standard requirement, but quantum resistance demands more.
- B. Shor's algorithm targets asymmetric cryptography (like RSA, ECC) and does not directly attack hash functions in the same way.
- D. Pre-image resistance for classical computers is a standard requirement, but quantum resistance demands more.
Quantum-Resistant Hashing
Cryptographic hash functions designed to remain secure against attacks by quantum computers, particularly those leveraging Grover's algorithm.
- Grover's algorithm can halve the effective security strength of a hash function.
- Requires significantly larger hash output sizes compared to classical hashes for equivalent security.
- Post-quantum cryptography research is actively developing and standardizing these algorithms.
Memory trick: Quantum attacks: Shor breaks keys, Grover finds hashes!