The One-Way to Hiding (O2H) theorem, first given by Unruh (J ACM 2015) and then restated by Ambainis et al. (CRYPTO 2019), is a crucial technique for solving the reprogramming problem in the quantum random oracle model (QROM). It provides an upper bound \(d\cdot \sqrt{\epsilon }\) for the distinguisher’s advantage, where d is the query depth and \(\epsilon \) denotes the advantage of a one-wayness attacker. Later, in order to obtain a tighter upper bound, Kuchta et al. (EUROCRYPT 2020) proposed the Measure-Rewind-Measure (MRM) technique and then proved the Measure-Rewind-Measure O2H (MRM-O2H) theorem, which provides the upper bound \(d\cdot \epsilon \) . They also proposed an open question: Can we combine their MRM technique with Ambainis et al.’s semi-classical oracle technique (CRYPTO 2019) or Zhandry’s compressed oracle technique (CRYPTO 2019) to prove a new O2H theorem with an upper bound even tighter than \(d\cdot \epsilon \) ? In this paper, we give an affirmative answer for the above question. We propose a new technique named Measure-Rewind-Extract (MRE) by combining the MRM technique with the semi-classical oracle technique. By using MRE technique, we prove the Measure-Rewind-Extract O2H (MRE-O2H) theorem, which provides the upper bound \(\sqrt{d}\cdot \epsilon \) . As an important application of our MRE-O2H theorem, for the , \(\textsf {FO}^{\bot }\) and \(\textsf {FO}_m^\bot \) proposed by Hofheinz et al. (TCC 2017), i.e., the key encapsulation mechanism (KEM) variants of the Fujisaki-Okamoto transformation, we prove the following results in the QROM:

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Measure-Rewind-Extract: Tighter Proofs of One-Way to Hiding and CCA Security in the Quantum Random Oracle Model

  • Jiangxia Ge,
  • Heming Liao,
  • Rui Xue

摘要

The One-Way to Hiding (O2H) theorem, first given by Unruh (J ACM 2015) and then restated by Ambainis et al. (CRYPTO 2019), is a crucial technique for solving the reprogramming problem in the quantum random oracle model (QROM). It provides an upper bound \(d\cdot \sqrt{\epsilon }\) for the distinguisher’s advantage, where d is the query depth and \(\epsilon \) denotes the advantage of a one-wayness attacker. Later, in order to obtain a tighter upper bound, Kuchta et al. (EUROCRYPT 2020) proposed the Measure-Rewind-Measure (MRM) technique and then proved the Measure-Rewind-Measure O2H (MRM-O2H) theorem, which provides the upper bound \(d\cdot \epsilon \) . They also proposed an open question: Can we combine their MRM technique with Ambainis et al.’s semi-classical oracle technique (CRYPTO 2019) or Zhandry’s compressed oracle technique (CRYPTO 2019) to prove a new O2H theorem with an upper bound even tighter than \(d\cdot \epsilon \) ? In this paper, we give an affirmative answer for the above question. We propose a new technique named Measure-Rewind-Extract (MRE) by combining the MRM technique with the semi-classical oracle technique. By using MRE technique, we prove the Measure-Rewind-Extract O2H (MRE-O2H) theorem, which provides the upper bound \(\sqrt{d}\cdot \epsilon \) . As an important application of our MRE-O2H theorem, for the , \(\textsf {FO}^{\bot }\) and \(\textsf {FO}_m^\bot \) proposed by Hofheinz et al. (TCC 2017), i.e., the key encapsulation mechanism (KEM) variants of the Fujisaki-Okamoto transformation, we prove the following results in the QROM: