On the IND-CCA security of post-quantum public-key encryption schemes

Time: Tuesday, January 14, 2020 - 4:00pm - 5:00pm
Type: Seminar Series
Presenter: Nina Bindel; Postdoctoral Researcher, Department of Combinatorics & Optimization - University of Waterloo
Room/Office: Room 107
J. Robert Mann, Jr. Engineering Student Center
10 Hillhouse Avenue
New Haven, CT 06511
United States

Department of Electrical Engineering Seminar

Nina Bindel
Postdoctoral Researcher
Department of Combinatorics & Optimization
University of Waterloo

“On the IND-CCA security of post-quantum public-key encryption schemes”

Abstract: If a general-purpose quantum computer can be built, it will break most widely-deployed public-key cryptography. The cryptographic community is busily designing new cryptographic systems to prepare for this risk, e.g., the (US-American) National Institute for Standards and Technology (NIST) is currently aiming at standardizing several quantum-safe digital signature and public-key encryption schemes (PKEs). After giving an update on the current status of the NIST's post-quantum standardization effort we will present to recent results on the security of PKEs.

First we will revisit the security loss when transforming an IND-CPA secure PKE to an IND-CCA secure key encapsulation mechanism (KEM) in the quantum random oracle model. We will explain how this result applies to candidates in the NIST standardization project.

Interestingly, most of the submitted PKEs are not perfectly correct schemes, i.e., sometimes honestly generated ciphertexts can't be encrypted correctly. Finding such a decryption failure poses a security risk that is also considered in our theoretical IND-CCA security analysis.

Surprisingly, correctly decrypted ciphertexts might pose a security risk as well, if the theoretical bounds coming from the security analysis are not respected. We will describe the attack and, again, show the impact on standardization candidates by presenting experimental data.

Bio: Nina Bindel is affiliated to the Institute for Quantum Computing (IQC) as a postdoctoral researcher at the Department of Combinatorics & Optimization at the University of Waterloo in Waterloo, Ontario, Canada.

Before joining the IQC, she was a postdoctoral researcher in the Cryptography and computer algebra group at TU Darmstadt where she also received her Ph.D. in September 2018 under the supervision of Johannes Buchmann.

Nina's research interest is mostly in the area of cryptography that is secure even in the presence of quantum computers, so-called post-quantum cryptography.

Hosted by: Professor Jakub Szefer