Tight time-space lower bounds for finding multiple collision pairs and their applications

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

We consider a collision search problem (CSP), where given a parameter C, the goal is to find C collision pairs in a random function (Formula presented) (where (Formula presented) using S bits of memory. Algorithms for CSP have numerous cryptanalytic applications such as space-efficient attacks on double and triple encryption. The best known algorithm for CSP is parallel collision search (PCS) published by van Oorschot and Wiener, which achieves the time-space tradeoff (Formula presented). In this paper, we prove that any algorithm for CSP satisfies (Formula presented), hence the best known time-space tradeoff is optimal (up to poly-logarithmic factors in N). On the other hand, we give strong evidence that proving similar unconditional time-space tradeoff lower bounds on CSP applications (such as breaking double and triple encryption) may be very difficult, and would imply a breakthrough in complexity theory. Hence, we propose a new restricted model of computation and prove that under this model, the best known time-space tradeoff attack on double encryption is optimal.

Original languageEnglish
Title of host publicationAdvances in Cryptology – EUROCRYPT 2020 - 39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Proceedings
EditorsAnne Canteaut, Yuval Ishai
PublisherSpringer
Pages405-434
Number of pages30
ISBN (Print)9783030457204
DOIs
StatePublished - 1 Jan 2020
Event39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2020 - Zagreb, Croatia
Duration: 10 May 202014 May 2020

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume12105 LNCS

Conference

Conference39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2020
Country/TerritoryCroatia
CityZagreb
Period10/05/2014/05/20

Keywords

  • Collision search problem
  • Cryptanalysis
  • Double encryption
  • Parallel collision search
  • Provable security
  • R-way branching program
  • Time-space tradeoff

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)

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