Paper 2015/1075

Cybersecurity in an era with quantum computers: will we be ready?

Michele Mosca


Quantum computers will break currently deployed public-key cryptography, and significantly weaken symmetric key cryptography, which are pillars of modern-day cybersecurity. Thus, before large-scale quantum computers are built, we need to migrate our systems and practices to ones that cannot be broken by quantum computers. For systems that aim to provide long-term confidentiality, this migration should happen even sooner. There are viable options for quantum-proofing our cryptographic infrastructure, but the road ahead is neither easy nor fast. Impressive progress in developing the building blocks of a fault-tolerant scalable quantum computer indicates that the prospect of a large-scale quantum computer is a medium-term threat. For example, I estimate a $1/2$ chance of breaking RSA-2048 by $2031$. In this note, I briefly overview the problem, the solutions and some of the next steps.

Note: This note is based on the abstract for a talk I gave at QCRYPT 2015 in Tokyo.

Available format(s)
Publication info
Preprint. MINOR revision.
cryptanalysisquantum cryptanalysispost-quantum cryptographyquantum cryptographyquantum-resistant cryptographyquantum-safe cryptographyquantum computing
Contact author(s)
mmosca @ uwaterloo ca
2015-11-05: received
Short URL
Creative Commons Attribution


      author = {Michele Mosca},
      title = {Cybersecurity in an era with quantum computers: will we be ready?},
      howpublished = {Cryptology ePrint Archive, Paper 2015/1075},
      year = {2015},
      note = {\url{}},
      url = {}
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