Journal of Cryptology

, Volume 30, Issue 2, pp 392–443 | Cite as

Acoustic Cryptanalysis

  • Daniel Genkin
  • Adi Shamir
  • Eran TromerEmail author


Many computers emit a high-pitched noise during operation, due to vibration in some of their electronic components. These acoustic emanations are more than a nuisance: They can convey information about the software running on the computer and, in particular, leak sensitive information about security-related computations. In a preliminary presentation (Eurocrypt’04 rump session), we have shown that different RSA keys induce different sound patterns, but it was not clear how to extract individual key bits. The main problem was the very low bandwidth of the acoustic side channel (under 20  kHz using common microphones, and a few hundred kHz using ultrasound microphones), and several orders of magnitude below the GHz-scale clock rates of the attacked computers. In this paper, we describe a new acoustic cryptanalysis key extraction attack, applicable to GnuPG’s implementation of RSA. The attack can extract full 4096-bit RSA decryption keys from laptop computers (of various models), within an hour, using the sound generated by the computer during the decryption of some chosen ciphertexts. We experimentally demonstrate such attacks, using a plain mobile phone placed next to the computer, or a more sensitive microphone placed 10 meters away.


Side channel attacks Acoustic emanations RSA Cryptanalysis 



Lev Pachmanov wrote much of the software setup used in our experiments, including custom signal acquisition programs. Avi Shtibel, Ezra Shaked, and Oded Smikt assisted in constructing and configuring the experimental setup. Assa Naveh assisted in various experiments and offered valuable suggestions. Sharon Kessler provided copious editorial advice. We thank Werner Koch, lead developer of GnuPG, for the prompt response to our disclosure and the productive collaboration in adding suitable countermeasures. We are indebted to Pankaj Rohatgi for inspiring the origin of this research; to Nir Yaniv for audio recording advice and use of the Nir Space Station studio; to National Instruments Israel for donating PCI-6052E and MyDAQ hardware; and to the anonymous reviewers for their valuable suggestions. This work was sponsored by the Check Point Institute for Information Security; by European Union’s Tenth Framework Programme (FP10/2010–2016) under Grant Agreement No. 259426 ERC-CaC, by the Leona M. & Harry B. Helmsley Charitable Trust; by the Israeli Ministry of Science and Technology; by the Israeli Centers of Research Excellence I-CORE program (center 4/11); and by NATO’s Public Diplomacy Division in the Framework of “Science for Peace.”


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Copyright information

© International Association for Cryptologic Research 2016

Authors and Affiliations

  1. 1.TechnionHaifaIsrael
  2. 2.Tel Aviv UniversityTel AvivIsrael
  3. 3.Weizmann Institute of ScienceRehovotIsrael

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