Certain Observations on ACORN v3 and the Implications to TMDTO Attacks

  • Akhilesh Anilkumar SiddhantiEmail author
  • Subhamoy Maitra
  • Nishant Sinha
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10662)


ACORN is a lightweight authenticated cipher which is one of the selected designs among the fifteen third round candidates. This is based on the underlying model of a stream cipher with 6 LFSRs of different lengths and three additional bits. In this paper we consider the scenario that certain amount of key stream bits and some portion of the state is known. Then we try to discover the rest of the state bits. For example, we show that the LFSR of length 47 can be recovered from 47 key stream bits and guessing the rest of the state bits. We also present the implication of such results towards mounting TMDTO attack on ACORN v3. We show that a TMDTO attack can be mounted with preprocessing complexity \(2^{171}\) and \(2^{180}\) (without and with the help of a SAT solver) and the maximum of online time, memory and data complexity \(2^{122}\) and \(2^{120}\) respectively. While our results do not refute any claim of the designer, these observations might be useful for further understanding of the cipher.


ACORN v3 Authenticated encryption CAESAR Cryptanalysis Stream cipher 



The first author would like to thank Department of Science and Technology DST-FIST Level-1 Program Grant No. SR/FST/MSI-092/2013 for providing the computational facilities.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Akhilesh Anilkumar Siddhanti
    • 1
    Email author
  • Subhamoy Maitra
    • 2
  • Nishant Sinha
    • 3
  1. 1.BITS Pilani, Goa CampusGoaIndia
  2. 2.Applied Statistics UnitIndian Statistical InstituteKolkataIndia
  3. 3.Department of Computer Science and EngineeringIndian Institute of Technology RoorkeeRoorkeeIndia

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