Cryptology ePrint Archive: Report 2015/223

New Distinguishers for Reduced Round Trivium and Trivia-SC using Cube Testers

Anubhab Baksi and Subhamoy Maitra and Santanu Sarkar

Abstract: In this paper we experiment with cube testers on reduced round Trivium that can act as a distinguisher. Using heuristics, we obtain several distinguishers for Trivium running more than 800 rounds (maximum 829) with cube sizes not exceeding 27. In the process, we also exploit state biases that has not been explored before. Further, we apply our techniques to analyse Trivia-SC, a stream cipher proposed by modifying the parameters of Trivium and used as a building block for TriviA-ck (an AEAD scheme, which is submitted to the ongoing CAESAR competition). We obtain distinguishers till 900 rounds of Trivia-SC with a cube size of 21 only and our results refute certain claims made by the designers. These are the best results reported so far, though our work does not affect the security claims for the ciphers with full initialization rounds, namely 1152.

Category / Keywords: secret-key cryptography / Cryptanalysis, Cube Tester, Stream Cipher, Trivium, Trivia-SC.

Original Publication (with minor differences): WCC 2015

Date: received 9 Mar 2015

Contact author: subho at isical ac in

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Version: 20150309:210541 (All versions of this report)

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