Cryptographic Protocols research group

Open Positions

We have currently several open positions, and we are both looking for new postdocs and new PhD students. Please email Helger Lipmaa for more information.

Group Description

The research group performs research in the generic area of cryptographic protocols, including but not only

  • Design of efficient zero-knowledge protocols
  • E-voting, esp. including
    • Verifiable (zero-knowledge) mixnets
    • Bulletin boards
  • Blockchain, esp. privacy in blockchain
  • Privacy-preserving data mining and machine learning
  • Relations with coding theory

The group is currently funded by the following projects:

  • Panoramix - H2020 project on verifiable mixnets
  • PRIViLEDGE - H2020 project on privacy in distributed ledgers
  • PRG49 - Estonian research grant on "Cryptographic Protocols and Coding Theory"

Please see the individual project places for more information about our research.

Team

  • Team leader: research professor Helger Lipmaa (dblp)
  • Ph.D. students:
    • Toomas Krips (dblp, PhD)
    • Behzad Abdolmaleki (dblp), Karim Baghery (dblp), Janno Siim (dblp, all started PhD studies in 2016)
    • Zaira Pindado (visiting PhD student)
  • M.Sc. students:
    • Janno Veeorg, Shahla Atapoor

Alumni (not complete)

  • Sven Laur (defended PhD in 2008, now a senior research fellow in Tartu)
  • Bingsheng Zhang (defended PhD in 2011, now a lecturer in Lancaster)
  • Prastudy Fauzi (defended PhD in 2017, now a postdoc in Aarhus)
  • Rafik Chaabouni (defended PhD in 2017, now a IT risk analyst, Pictet Group)
  • Michal Zajac (dblp) (now at Clearmatics, London-based blockchain company)
  • Gennaro Avitabile (Erasmus exchange student from Salerno, Italy, 01.09.18 -- 14.02.18)
  • Hamidreza Khoshakhlagh (Ph.D. student 01.09.18 - 31.05.19, now a PhD student in Aarhus)

Recent Publications

2016

  • Prastudy Fauzi, Helger Lipmaa and Michał Zając. A Shuffle Argument Secure in the Generic Model. In Jung Hee Cheon and Tsuyoshi Takagi, editors, ASIACRYPT 2016, volume ? of Lecture Notes in Computer Science, pages 841--872, Hanoi, Vietnam, December 4--8, 2016. Springer, Heidelberg.
  • Helger Lipmaa. Prover-Efficient Commit-And-Prove Zero-Knowledge SNARKs. In David Pointcheval, Abderrahmane Nitaj and Tajjeeddine Rachidi, editors, Africacrypt 2016, volume 10032 of Lecture Notes in Computer Science, pages 200--216, Fes, Morocco, April 13--15, 2016. Springer, Heidelberg. Invited to IJACT as one of the three best papers
  • Prastudy Fauzi and Helger Lipmaa. Efficient Culpably Sound NIZK Shuffle Argument without Random Oracles. In Kazue Sako, editor, CT-RSA 2016, volume 9610 of Lecture Notes in Computer Science, pages 200--216, San Franscisco, CA, USA, February 29--March 4, 2016. Springer, Heidelberg.

2017

  • Helger Lipmaa. Prover-efficient commit-and-prove zero-knowledge SNARKs. International Journal of Applied Cryptography (IJACT), Vol. 3, No. 4, 2017. This is an invited journal version of the earlier Africacrypt 2016 paper
  • Behzad Abdolmaleki, Karim Baghery, Helger Lipmaa and Michal Zajac. A Subversion-Resistant SNARK. In Thomas Peyrin and Tsuyoshi Takagi, editors, ASIACRYPT (3) 2017, volume 10626 of Lecture Notes in Computer Science, pages 3--33, Hong Kong, China, December 3--7, 2017. Springer, Heidelberg. Invited to Journal of Cryptology as one of the three best papers
  • Prastudy Fauzi, Helger Lipmaa, Janno Siim and Michal Zajac. An Efficient Pairing-Based Shuffle Argument. In Thomas Peyrin and Tsuyoshi Takagi, editors, ASIACRYPT (2) 2017, volume 10625 of Lecture Notes in Computer Science, pages 97--127, Hong Kong, China, December 3--7, 2017. Springer, Cham.
  • Helger Lipmaa and Kateryna Pavlyk. A Simpler Rate-Optimal CPIR Protocol. In Aggelos Kiayias, editor, FC 2017, volume ? of Lecture Notes in Computer Science, pages ?--?, Malta, April 3--7, 2017. Springer, Heidelberg. Accepted.
  • Helger Lipmaa. Optimally Sound Sigma Protocols Under DCRA. In Aggelos Kiayias, editor, FC 2017, volume ? of Lecture Notes in Computer Science, pages ?--?, Malta, April 3--7, 2017. Springer, Heidelberg. Accepted.
  • Florian Bourse, Fabrice Benhamouda and Helger Lipmaa. CCA-Secure Inner-Product Functional Encryption from Projective Hash Functions. In Serge Fehr, editor, PKC 2017, volume 10175 of Lecture Notes in Computer Science, pages 36--66, Amsterdam, Netherlands, March 28--31, 2017. Springer, Heidelberg.

2018

  • Aggelos Kiayias, Annabell Kuldmaa, Helger Lipmaa, Janno Siim and Thomas Zacharias. On the Security Properties of e-Voting Bulletin Boards. In Dario Catalano and Roberto de Prisco, editors, SCN 2018, volume 11035 of Lecture Notes in Computer Science, pages 505--523, Amalfi, Italy, September 5--7, 2018. Springer, Cham.

2019

  • Behzad Abdolmaleki, Karim Baghery, Helger Lipmaa, Janno Siim and Michal Zajac. DL-Extractable UC-Commitment Schemes. In Robert Deng and Moti Yung, editors, ACNS 2019, volume ? of Lecture Notes in Computer Science, pages ?--?, Bogotá , Colombia, June 5--7, 2019. Springer, Heidelberg. eprint version
  • Behzad Abdolmaleki, Karim Baghery, Helger Lipmaa, Janno Siim and Michal Zajac. UC-Secure CRS Generation for SNARKs. In Johannes Buchmann, Abderrahmane Nitaj and Tajjeeddine Rachidi, editors, Africacrypt 2019, volume ? of Lecture Notes in Computer Science, pages ?--?, Rabat, Morocco, July 9--11, 2019. Springer, Heidelberg.
  • Karim Baghery. On the Efficiency of Privacy-Preserving Smart Contract Systems. In Johannes Buchmann, Abderrahmane Nitaj and Tajjeeddine Rachidi, editors, Africacrypt 2019, volume ? of Lecture Notes in Computer Science, pages ?--?, Rabat, Morocco, July 9--11, 2019. Springer, Heidelberg.