Will You Cross the Threshold for Me? Generic Side-Channel Assisted Chosen-Ciphertext Attacks on NTRU-based KEMs

Prasanna Ravi, Martianus Frederic Ezerman, Shivam Bhasin, Anupam Chattopadhyay, Sujoy Sinha Roy

Research output: Contribution to journalArticlepeer-review

Abstract

In this work, we propose generic and novel side-channel assisted chosen-ciphertext attacks on NTRU-based key encapsulation mechanisms (KEMs). These KEMs are IND-CCA secure, that is, they are secure in the chosen-ciphertext model. Our attacks involve the construction of malformed ciphertexts. When decapsulated by the target device, these ciphertexts ensure that a targeted intermediate variable becomes very closely related to the secret key. An attacker, who can obtain information about the secret-dependent variable through side-channels, can subsequently recover the full secret key. We propose several novel CCAs which can be carried through by using side-channel leakage from the decapsulation procedure. The attacks instantiate three different types of oracles, namely a plaintext-checking oracle, a decryption-failure oracle, and a full-decryption oracle, and are applicable to two NTRU-based schemes, which are NTRU and NTRU Prime. The two schemes are candidates in the ongoing NIST standardization process for post-quantum cryptography. We perform experimental validation of the attacks on optimized and unprotected implementations of NTRU-based schemes, taken from the open-source pqm4 library, using the EM-based side-channel on the 32-bit ARM Cortex-M4 microcontroller. All of our proposed attacks are capable of recovering the full secret key in only a few thousand chosen ciphertext queries on all parameter sets of NTRU and NTRU Prime. Our attacks, therefore, stress on the need for concrete side-channel protection strategies for NTRU-based KEMs.
Original languageEnglish
Pages (from-to)722–761
Number of pages40
JournalIACR Transactions on Cryptographic Hardware and Embedded Systems
Volume2022
Issue number1
DOIs
Publication statusPublished - 2022

Keywords

  • lattice based cryptography
  • Side channel attacks
  • Post-quantum cryptography
  • learning with error
  • chosen ciphertext attack
  • key encapsulation mechanism
  • public key encryption
  • learning with rounding
  • lattice-based cryptography
  • electromagnetic-based side-channel attack

ASJC Scopus subject areas

  • Software
  • Artificial Intelligence
  • Signal Processing
  • Hardware and Architecture
  • Computer Networks and Communications
  • Computer Graphics and Computer-Aided Design

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