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A cryptocurrency project aims to use a hashing algorithm that is resistant to quantum computer attacks. The developers are concerned that traditional hash functions might eventually be vulnerable to quantum algorithms that could find collisions more efficiently. Which characteristic is primarily sought in a post-quantum cryptographic hashing algorithm for this purpose?
- APre-image resistance against Grover's algorithm
- BResistance to quantum collision-finding algorithms
- CCollision resistance against Shor's algorithm
- DSecond pre-image resistance against quantum parallelism
Show answer & explanationAnswer & explanation
Correct answer: B. Resistance to quantum collision-finding algorithms
The primary concern for hashing algorithms in a quantum computing context is their collision resistance. While Grover's algorithm can speed up pre-image attacks, quantum algorithms like those based on the birthday paradox (e.g., in a quantum search) can find collisions in hash functions much faster than classical methods. Therefore, a post-quantum hash needs to specifically resist quantum collision-finding.
Why the other options are wrong
- A. Grover's algorithm speeds up search problems, including pre-image attacks on hashes, but collision resistance is a more fundamental and harder problem to solve quantumly for hashes.
- C. Shor's algorithm targets asymmetric cryptography (factoring, discrete log), not directly hash collision resistance.
- D. Quantum parallelism is a general concept; second pre-image resistance is a property, but the specific quantum threat to hashes is collision finding.
Post-Quantum Cryptography (PQC)
Cryptographic algorithms designed to be secure against attacks from quantum computers, which could break many of the currently used public-key cryptographic algorithms.
- Aims to replace current public-key cryptography.
- Focuses on algorithms resistant to Shor's and Grover's algorithms.
- Includes lattice-based, code-based, hash-based, and multivariate polynomial cryptography.
Memory trick: Quantum hashes are like super-strong locks, even quantum computers can't pick them.