Cryptanalysis of ITRU

TL;DR

This paper presents a frequency analysis attack on the ITRU cryptosystem, challenging claims of its superior security and highlighting vulnerabilities in its design based on the ring of integers.

Contribution

The paper introduces a novel cryptanalysis method using frequency analysis to break the ITRU cryptosystem, revealing security weaknesses.

Findings

Frequency analysis can effectively recover messages encrypted with ITRU.

ITRU's security claims are undermined by the proposed attack.

The attack exposes vulnerabilities in ITRU's ring of integers-based structure.

Abstract

ITRU cryptosystem is a public key cryptosystem and one of the known variants of NTRU cryptosystem. Instead of working in a truncated polynomial ring, ITRU cryptosystem is based on the ring of integers. The authors claimed that ITRU has better features comparing to the classical NTRU, such as having a simple parameter selection algorithm, invertibility, and successful message decryption, and better security. In this paper, we present an attack technique against the ITRU cryptosystem, and it is mainly based on a simple frequency analysis on the letters of ciphertexts.