The do's and don'ts of quantum memory in cryptanalysis

<p>This thesis refines the estimates of the costs to attack three different cryptographic problems. To get there, I first survey some fundamental issues in quantum computing. This narrows the scope of the capabilities of quantum computers and the engineering costs to build and run them. I then...

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Main Author: Jaques, S
Other Authors: Benjamin, S
Format: Thesis
Language:English
Published: 2023
Subjects:
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author Jaques, S
author2 Benjamin, S
author_facet Benjamin, S
Jaques, S
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description <p>This thesis refines the estimates of the costs to attack three different cryptographic problems. To get there, I first survey some fundamental issues in quantum computing. This narrows the scope of the capabilities of quantum computers and the engineering costs to build and run them. I then focus on “QRAM”, a type of quantum memory. The question with QRAM is whether quantum computers could cheaply access memory in superposition. I argue that they could not, and that quantum computers must pay a steep price to access memory.</p> <p>I then analyse circuits to attack elliptic curve cryptography with Shor’s algo- rithm. I find that even expensive QRAM improves these circuits. Next I provide some optimisations and parallelisation strategies for Kuperberg’s algorithm. This algorithm can attack “CSIDH”, a type of post-quantum cryptography. Again QRAM is an effective tool: huge classical co-processing costs offset the expense of each quantum memory access. Finally I provide an algorithm for the golden collision problem, a generalisation of “meet-in-the-middle” attacks. If stable, error- free memory exists, then this algorithm could acheive an exponential advantage in total cost. However, the run-time of this algorithm is too high, so I show a more effective use of massive arrays of quantum hardware. This second algorithm has a higher cost but parallelises nearly perfectly.</p>
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spelling oxford-uuid:fd1412a1-2229-4b48-bbbe-95d03c79ba002024-12-12T07:58:28ZThe do's and don'ts of quantum memory in cryptanalysisThesishttp://purl.org/coar/resource_type/c_db06uuid:fd1412a1-2229-4b48-bbbe-95d03c79ba00cryptographyquantum computingEnglishHyrax Deposit2023Jaques, SBenjamin, SPetit, C<p>This thesis refines the estimates of the costs to attack three different cryptographic problems. To get there, I first survey some fundamental issues in quantum computing. This narrows the scope of the capabilities of quantum computers and the engineering costs to build and run them. I then focus on “QRAM”, a type of quantum memory. The question with QRAM is whether quantum computers could cheaply access memory in superposition. I argue that they could not, and that quantum computers must pay a steep price to access memory.</p> <p>I then analyse circuits to attack elliptic curve cryptography with Shor’s algo- rithm. I find that even expensive QRAM improves these circuits. Next I provide some optimisations and parallelisation strategies for Kuperberg’s algorithm. This algorithm can attack “CSIDH”, a type of post-quantum cryptography. Again QRAM is an effective tool: huge classical co-processing costs offset the expense of each quantum memory access. Finally I provide an algorithm for the golden collision problem, a generalisation of “meet-in-the-middle” attacks. If stable, error- free memory exists, then this algorithm could acheive an exponential advantage in total cost. However, the run-time of this algorithm is too high, so I show a more effective use of massive arrays of quantum hardware. This second algorithm has a higher cost but parallelises nearly perfectly.</p>
spellingShingle cryptography
quantum computing
Jaques, S
The do's and don'ts of quantum memory in cryptanalysis
title The do's and don'ts of quantum memory in cryptanalysis
title_full The do's and don'ts of quantum memory in cryptanalysis
title_fullStr The do's and don'ts of quantum memory in cryptanalysis
title_full_unstemmed The do's and don'ts of quantum memory in cryptanalysis
title_short The do's and don'ts of quantum memory in cryptanalysis
title_sort do s and don ts of quantum memory in cryptanalysis
topic cryptography
quantum computing
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