Which of the following is least vulnerable to cryptographically relevant quantum computers (CRQC)? (Wentz QOTD)
A. Stream ciphers
B. The RSA Digital Signature Algorithm
C. Key agreement using Diffie-Hellman
D. Key exchange using RSA public-key encryption

Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.

My suggested answer is A. Stream ciphers.

Wentz’s book, The Effective CISSP: Security and Risk Management, helps CISSP and CISM aspirants build a solid conceptual security model. It is a tutorial for information security and a supplement to the official study guides for the CISSP and CISM exams and an informative reference for security professionals.

Cryptographically Relevant Quantum Computers (CRQCs) are quantum computers capable of breaking current cryptography. Post-quantum cryptography (PQC) is the research topic to identify cryptographic solutions that may be secure against quantum threats.

• Stream and block ciphers used in symmetric encryption are mainly safe from quantum computing attacks.
• However, when it comes to asymmetric encryption, “most of the popular public key ciphers are based on the difficulty of factoring integers or the discrete logarithm problem, both of which can be solved by Shor’s algorithm. In particular, the RSA, Diffie–Hellman, and elliptic curve Diffie–Hellman algorithms could be broken.” (Wikipedia)

Reference

• Peter Shor
• Paul Benioff
• Quantum computing
• Quantum Computing and the DNS
• Quantum Computing and Post-Quantum Cryptography
• Will Symmetric and Asymmetric Encryption Withstand the Might of Quantum Computing?
• DHS Issues Roadmap for Transition to Post-Quantum Cryptography
• Quantum technology and its impact on security in mobile networks
• ANSSI VIEWS ON THE POST-QUANTUM CRYPTOGRAPHY TRANSITION
• Quantum computers mean cryptography needs to change, and soon
• Are Cryptographically Relevant Quantum Computers Prepared to Disrupt Classical Encryption

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以下哪項最不容易受到密碼相關量子計算機 (CRQC) 的攻擊？ (Wentz QOTD)
A. 流密碼
B. RSA 數字簽名算法
C. 使用 Diffie-Hellman 的密鑰協商
D. 使用 RSA 公鑰加密的密鑰交換