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An Unconditionally Hiding and Long-Term Binding Post-Quantum Commitment Scheme

Cabarcas, Daniel and Demirel, Denise and Göpfert, Florian and Lancrenon, Jean and Wunderer, Thomas :
An Unconditionally Hiding and Long-Term Binding Post-Quantum Commitment Scheme.

[Report] , (2015)

Abstract

Commitment schemes are among cryptography's most important building blocks. Besides their basic properties, hidingness and bindingness, for many applications it is important that the schemes applied support proofs of knowledge. However, all existing solutions which have been proven to provide these protocols are only computationally hiding or are not resistant against quantum adversaries. This is not suitable for long-lived systems, such as long-term archives, where commitments have to provide security also in the long run. Thus, in this work we present a new post-quantum unconditionally hiding commitment scheme that supports (statistical) zero-knowledge protocols and allows to refreshes the binding property over time. The bindingness of our construction relies on the approximate shortest vector problem, a lattice problem which is conjectured to be hard for polynomial approximation factors, even for a quantum adversary. Furthermore, we provide a protocol that allows the committer to prolong the bindingness property of a given commitment while showing in zero-knowledge fashion that the value committed to did not change. In addition, our construction yields two more interesting features: one is the ability to "convert" a Pedersen commitment into a lattice-based one, and the other one is the construction of a hybrid approach whose bindingness relies on the discrete logarithm and approximate shortest vector problems.

Item Type: Report
Erschienen: 2015
Creators: Cabarcas, Daniel and Demirel, Denise and Göpfert, Florian and Lancrenon, Jean and Wunderer, Thomas
Title: An Unconditionally Hiding and Long-Term Binding Post-Quantum Commitment Scheme
Language: English
Abstract:

Commitment schemes are among cryptography's most important building blocks. Besides their basic properties, hidingness and bindingness, for many applications it is important that the schemes applied support proofs of knowledge. However, all existing solutions which have been proven to provide these protocols are only computationally hiding or are not resistant against quantum adversaries. This is not suitable for long-lived systems, such as long-term archives, where commitments have to provide security also in the long run. Thus, in this work we present a new post-quantum unconditionally hiding commitment scheme that supports (statistical) zero-knowledge protocols and allows to refreshes the binding property over time. The bindingness of our construction relies on the approximate shortest vector problem, a lattice problem which is conjectured to be hard for polynomial approximation factors, even for a quantum adversary. Furthermore, we provide a protocol that allows the committer to prolong the bindingness property of a given commitment while showing in zero-knowledge fashion that the value committed to did not change. In addition, our construction yields two more interesting features: one is the ability to "convert" a Pedersen commitment into a lattice-based one, and the other one is the construction of a hybrid approach whose bindingness relies on the discrete logarithm and approximate shortest vector problems.

Uncontrolled Keywords: Secure Data;Solutions;S6;PRISMACLOUD;P1;Primitives;unconditionally hiding commitments, post-quantum, lattice-based cryptography, long-term security, proof of knowledge
Divisions: DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 1119: CROSSING – Cryptography-Based Security Solutions: Enabling Trust in New and Next Generation Computing Environments
Department of Computer Science > Theoretical Computer Science - Cryptography and Computer Algebra
LOEWE > LOEWE-Zentren > CASED – Center for Advanced Security Research Darmstadt
Department of Computer Science > Theoretical Computer Science - Cryptography and Computer Algebra > Long-term Security
Profile Areas > Cybersecurity (CYSEC)
Department of Computer Science > Theoretical Computer Science - Cryptography and Computer Algebra > Post-Quantum Cryptography
LOEWE > LOEWE-Zentren
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
Department of Computer Science
Profile Areas
LOEWE
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 15 Nov 2016 23:15
Identification Number: TUD-CS-2015-0141
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