Basic data

• Name: Helger Lipmaa.
• Citizenship: Estonian.
• Senior researcher, Cybernetica AS, Estonia.
• Professor, Tallinn University, Estonia (0.3).
• Member of the board of directors of the IACR (International Association for Cryptologic Research).
• Main research area: cryptology, including implementations, cryptanalysis, protocols, applications and theory of cryptography; also theoretical computer science, algorithms.
• http://research.cyber.ee/~lipmaa

Education and Work Experience

1. Education:

   1979-1987

   Pärnu Ülejõe Gümnaasium (primary education).

   1987-1990

   Pärnu Koidula Gümnaasium (high school, special class of mathematics and physics).

   1990-1993

   University of Tartu, Department of Mathematics (undergraduate).

   1993-1995

   University of Tartu, Department of Mathematics, Institute of Computer Science (master student).

   1995-1999

   University of Tartu, Department of Mathematics, Institute of Computer Science (PhD student).
2. Academic degrees:
   1. Master of informatics at the University of Tartu, 1995. Subject: "Review of communication complexity" (in Estonian).
   2. PhD of informatics (cum laude) at the University of Tartu, 1999. Subject: "Secure and Efficient Time-Stamping Systems."
3. Work Experience:

   1989

   Computer lab manager, Pärnu, Estonia.

   1991-1991

   Programmer, Pärnu Commerce Bank, Estonia.

   1992-1992

   Programmer, MesoCom Ltd (large scale databases), Estonia.

   1994-1995

   System-administrator and webmaster at the Department of Mathematics, University of Tartu, Estonia (Linux, WWW, ...).

   1995-1995

   Junior researcher at Institute of Computer Science, University of Tartu (complexity theory), Estonia.

   01.11.1995-12.12.1995

   Senior assistant at Institute of Computer Science, University of Tartu (complexity theory), Estonia.

   12.11.1996-28.07.1997

   Junior researcher at Institute of Cybernetics, Tallinn (cryptography), Estonia.

   01.08.1997-31.03.2000

   Senior research engineer at Küberneetika AS, a state-owned research and development company, a spin-off of Institute of Cybernetics (cryptography), Estonia.

   01.02.2000-31.03.2001

   Half-time lecturer (assistant professor) at Institute of Computer Science, University of Tartu, Estonia.

   01.04.2000-31.07.2000

   Researcher at Telecommunications Software and Multimedia Laboratory (TML), Helsinki University of Technology, Finland. (50%)

   01.08.2000-31.07.2001

   Senior researcher at the TML, Helsinki University of Technology, Finland.

   01.08.2001-31.12.2004

   Professor (pro tem) at the Laboratory for Theoretical Computer Science, Helsinki University of Technology, Finland.

   01.01.2005-31.03.2005

   Teaching researcher at the Laboratory for Theoretical Computer Science, Helsinki University of Technology, Finland.

   01.04.2005-31.08.2006

   Senior researcher, Cybernetica AS, Estonia.

   01.04.2005-31.08.2006

   Professor, University of Tartu, Estonia. (50%)

   01.09.2006-31.07.2008

   Senior lecturer, University College London, UK.

   01.08.2008-...

   Senior researcher, Cybernetica AS, Estonia.

   15.09.2008-31.08.2009

   Docent (associate professor), University of Tartu, Estonia. (25%)

   01.11.2009-...

   Professor, Tallinn University, Estonia. (30%)

Awards and main achievements (incomplete)

1987

Seventh place at the Estonian Chemistry Olympiad.

1988

Fourth place at the Estonian Mathematics Olympiad.

1990

Third place at the Estonian Mathematics Olympiad, fourth place at the Estonian Olympiad of Informatics. Member of the Estonian team at the Soviet Informatics Olympiad.

1992

Award from INTENTIA Dataarkitekten AB for successful studies.

1993

Finished undergraduate studies in 3 years instead of 4 (5/5 grades in all mathematical subjects).

1998

My first ever submitted paper was accepted to CRYPTO, the leading annual cryptographic conference (acceptance ratio 22.9%).

1998

Award from Estonian Science Foundation, Commission for Exact Sciences, for successful research.

1999

Publication "Time-stamping with Binary-linking schemes" was the only publication of high-importance from Institute of Computer Science, University of Tartu, mentioned in "Overview of Estonian Research and Development, 1996-1999".

1999

Award from Estonian Science Foundation, Commission for Exact Sciences, for successful research.

2000

Publication "Accountable Certificate Management using Undeniable Attestations" (ACM CCS 2000) invited to the Journal of Computer Security as one of the three best papers of ACM CCS 2000, a leading conference on general data security. (ACM CCS 2000 had acceptance ratio 21.4%)

2000

My student Oleg Mürk got an award from Estonian Academy of Sciences for successful research during undergraduate studies.

2001

Professor (pro tem) position at the Helsinki University of Technology at age 29, probably one of the youngest professors at this university.

2005

My student Johan Wallén got the Best Finnish Computer Science MSc Thesis Award by The Finnish Society for Computer Science.

2005

My work on cryptographic protocols was named as one of the two main achievements of the Institute of Computer Science, University of Tartu, 2005. (Another main achievement was Peeter Laud's work, with papers in ACM CCS 2005 etc.)

2006

My student Ago-Erik Riet won a prestigious stipend from Skype to continue graduate studies at the Cambridge University.

2006

Senior lecturer position at University College London, one of top 25 universities in the world.

2009

My student Ho Bae (UCL) has won the best paper award at a competition run by the National Intelligence Service of the Republic of Korea. The topic is related to Private Information Retrieval.

Organisational activities and services to community

• Doctoral school in computer science at University of Latvia, foreign representative for the governing board of the school.
• External reviewer for the next grant organisations: Hongkong's Research Grants Council (Competitive Earmarked Research Grant).
• Membership in steering committees: Nordic Workshop on Secure IT Systems (annual, Nordsec, 2002...), the Estonian Winter School in Computer Science (annual, 1998...), Estonian Theory Days (twice a year, 2002...).
• General chair: Eurocrypt 2011 (Tallinn, Estonia, 2011), Ecrypt II Hash function workshop (Tallinn, Estonia, 2011 - with Andrea Röck), VOTEID 2011 (Tallinn, Estonia, 2011).
• Program Committee chair: Estonian Winter School in Computer Science 1998 (Palmse, Estonia), Seminar on Network Security 2002 (Sjökulla, Finland), NordSec 2005 (Tartu, Estonia - with Dieter Gollman), Inscrypt 2006 (Beijing, China - with Moti Yung), VoteID 2011 (Tallinn, Estonia - with Aggelos Kiayias).
• 42 Program Committee memberships (as a non-chair): SAC 2002 (St. John's, Newfoundland, Canada), FC 2003 (Guadeloupe), FSE 2003 (Lund, Sweden), WISA 2003 (Jeju Island, Korea), ISC 2003 (Bristol, UK), NordSec 2003 (Gjøvik, Norway), IWAP 2003 (Kokura, Japan), INDOCRYPT 2003 (Delhi, India), FC 2004 (Key West, FL, USA), ACNS 2004 (Yellow Mountain, China), ACM CCS 2004 (Washington, D.C., USA), Privacy and Security Aspects of Data Mining 2004 (Brighton, UK), NordSec 2004 (Helsinki, Finland), FC 2005 (Roseau, The Commonwealth Of Dominica), CT-RSA 2005 (San Franscisco, CA, USA), ISC 2005 (Singapore), PSDM 2005 (New Orleans, LA, USA), ICISC 2005 (Seoul, Korea), FC 2006 (Anguilla BWI), Eurocrypt 2006 (St Petersburg, Russia), WISA 2006 (Jeju Island, Korea), ISC 2006 (Samos Island, Greece), NordSec 2006 (Linköping, Sweden), ICISC 2006 (Busan, Korea), PADM 2006 (Hong Kong, China), CT-RSA 2007 (Berkeley, Ca, USA), WCC 2007 (Circester, UK), PADM 2007 (Omaha, USA), ISC 2007 (Valparaiso, Chile), ProvSec 2008 (Shanghai, China), Indocrypt 2008 (Kharagpur, India), Africacrypt 2009 (Gammarth, Tunisia), ProvSec 2009 (Guanzhou, China), CANS 2009 (Kanazawa, Japan), RLCPS 2010 (Tenerife, Spain), FC 2010 (Tenerife, Spain), CT-RSA 2010 (Berkeley, USA), Eurocrypt 2010 (Monaco), ESSCAS 2010 (Pedase, Estonia), NordSec 2010 (Helsinki, Finland), FC 2011 (St Lucia), RLCP 2011 (St Lucia), ESSCAS 2011 (Pedase, Estonia), ECML/PKDD 2011 (Athens, Greece), NordSec 2011 (Tallinn, Estonia), CANS 2011 (Sanya, China), FC 2012 (Bonaire, Netherlands Antilles).
• Additionally, reviewed for ACM Transactions on Information and System Security, IEEE International Symposium on Circuits and Systems (ISCAS), IEEE Transactions on VLSI Systems, International Journal on Information Security, Nordic Journal of Computing, Information Processing Letters (2004), Eurocrypt (..., 2005), Fast Software Encryption (FSE) Workshop (..., 2002), International Conference on Information Security and Cryptology (ICISC, ..., 2003), International Workshop on Information Security (ISW) and many other journals and conferences. (This section is very incomplete.)
• Session chair: Information Security Conference 2002 (São Paulo), Fast Software Encryption 2003 (Lund, Sweden), NordSec 2003 (Gjøvik, Norway), Financial Cryptography 2004 (Key West, FL, USA), Public Key Cryptography 2004 (Singapore), NordSec 2004 (Espoo, Finland), ICALP 2005 (Lisboa, Portugal), ICICS 2005 (Beijing, China), CANS 2005 (Xiamen, China), Eurocrypt 2006 (St Petersburg, Russia), Inscrypt 2006 (Beijing, China), CANS 2008 (Hong Kong, China), VOTEID 2009 (Luxembourg), NordSec 2009 (Oslo, Norway), Eurocrypt 2010 (Monaco), ESORICS 2010 (Athens). Estonian Winter School in Computer Science and Estonian Theory Days (many times).
• Rump session chair: Inscrypt 2006 (Beijing, China).
• The rest:
  • One of the organisers of the 1998 cryptography seminars in Tartu.
  • One of the organisers of the 1998-99 quantum computing seminars in Tartu.
  • One of the organisers of the 2000 seminar on the "Information Technology And Its Business Aspects" in Tartu.

Visibility

• As of 01.02.2011, according to Scholar.Google.Com, I have 1550 citations and H-index 23. (See http://research.cyber.ee/~lipmaa/cites/ for more information.)

Grants

1994

Tempus S_JEP-06145-94 grant, 3 month study period in Aarhus University, Complexity Theory.

1996

Tempus Individual Mobility Grant, 4.5 month study period in Aarhus University.

1997

Estonian Science Foundation grant, "Research and Studies in the Field of Cryptology".

2000

Senior researcher grant from TEKES (Finnish National Technology Agency) for one year. Results: three papers.

2001

AWACS-HUT grant for two months (Nokia). Results: two papers and one patent application.

2001-2005

Scientific leader of the Krypto project at the HUT, funded by the Finnish Defence Forces. From 2002 to 2004 employed Markku-Juhani O. Saarinen and Johan Wallén, in 2005 employed Johan Wallén and Emilia Käsper. (From April 1, 2005, project was led by prof. Kaisa Nyberg.)

2004-2007

Cryptology and Data-mining (CRYDAMI) project, HUT, funded by the Finnish Academy of Sciences. Employed one PhD student (Sven Laur). (From April 1, 2005, project was led by prof. Kaisa Nyberg.)

2005-2007

Base funding grant from the University of Tartu to start up a new research project. Subject: "Cryptographic protocols".

2006-2008

ETF (Estonian Science Foundation) grant 6848, "Privacy-Preserving Data Mining: Cryptographic Methods."

2009-2011

ETF (Estonian Science Foundation) grant 8058, "Efficient Cryptocomputing."

1994-95

Estonian Science Foundation grant. no. 1203, "Counting hierarchy and complexity of Boolean formulae with quantifiers". (Grant owner: Mati Tombak)

1998

Estonian Science Foundation grant 3742, "Digital Time-Stamping".

1999

Phare HESR grant "Time-Stamping Server". Results (combined with the previous grant): 3 papers, PhD thesis and one patent application.

2004-2005

Participant of the GO-SEC project (HUT, funded by the Tekes), 8 months. Employed one MSc student (Emilia Käsper).

2006-...

Target funding "Theoretical and Practical Security of Heterogeneous Information Systems" (grant owner Ahto Buldas)

Teaching qualifications

1. As the principal investigator from University of Tartu, participated in creating a joint Nordic Master Programme in data security and mobile computing, NordSecMob, http://nordsecmob.tkk.fi/
2. Pedagogical training: attended a course on Didactics of Informatics (1992)
3. Practical experience of teaching:
   • Lead several exercise sessions in 1994... 1996
   • Given lecture courses:
     • "Introduction to Cryptology", Tallinn Technical University, Spring 1997. (2 hours a week)
     • "Cryptology", University of Tartu, Autumn 1997. (2 hours a week)
     • "Cryptology", University of Tartu, Spring 2000. (2 hours a week). Course notes in Estonian.
     • "Seminar on Network Security", Helsinki University of Technology (HUT), Autumn 2000.
     • "Methods of Cryptology", HUT, Spring 2001. (2 hours a week)
     • "Special Course on Cryptology", HUT, Autumn 2001-2003. (2 hours a week)
     • "Seminar on Cryptology and Security Protocols", HUT, Autumn 2001.
     • "Cryptography and Data Security", HUT, Spring 2002-2004. (3 hours a week) Slides in English
     • "Cryptology: Special Topics", HUT, Spring 2002-2005. (2 hours a week)
     • "Postgraduate Course in Theoretical Computer Science", HUT, Autumn 2004. (2 hours a week)
     • "Research Seminar in Cryptography", University of Tartu, Autumn 2005. (2 hours a week) - student evaluation 4.67/5 (average in Institute: 3.64/5)
     • "Cryptographic Protocols", University of Tartu, Spring 2006. (2 hours a week)
     • "Graduate Seminar in Cryptography", University of Tartu, Spring 2006. (2 hours a week)
     • "Crypto II", University College London, Spring 2008. (total 30 hours)
     • "Graduate Seminar in Cryptography", University of Tartu, Autumn 2008. (2 hours a week)
     • "Research Seminar in Cryptography", University of Tartu, Spring 2009. (2 hours a week)
   • Lecture courses in summer/winter schools:
     • "Zero-knowledge: theory and applications" in Nordic Research Training course "Cryptology and Its Applications", Bergen, June 10-18, 2004
   • PhD theses supervised: Sven Laur (2008, Helsinki University of Technology).
   • BSc/MSc theses supervised:
     • From the University of Tartu: Piret Ulp (BSc in 1998, cum laude), Meelis Roos (MSc in 1999, cum laude), Priit Karu (semester work 1999, BSc 2000, cum laude), Rasmus Alop (semester work 1999), Oleg Mürk (semester work, 2000, for this Oleg won an award from Estonian Academy of Sciences; BSc thesis, 2001, cum laude), Sven Laur (MSc thesis 2002, cum laude), Emilia Käsper (MSc 2006, Complexity Analysis of Hardware-Assisted Attacks on A5/1)
     • From the Helsinki University of Technology: Lauri Tarkkala (MSc in 2001), Johan Wallén (MSc in 2003, the Best Finnish Computer Science MSc Thesis Award by The Finnish Society for Computer Science, 2005)
     • From University College London: Ho Bae and Bingsheng Zhang (co-supervisor with Jens Groth, MSc 2008).
   • Current students: Bingsheng Zhang, University of Tartu PhD student since September 2009 (MSc from University College London, 2008). Rafik Chaabouni (cosupervised with Serge Vaudenay from February 2011).
   • Joint papers with students: 6 with Sven Laur, 2 with Johan Wallén, 2 with Bingsheng Zhang.
   • Opponent of the next PhD theses:
     • Jan Willemson (PhD thesis "Size-efficient Interval Time Stamps", University of Tartu, 2002).
     • Lan Duy Nguyen (PhD thesis "Cryptographic-based Privacy Enhanching Technology", University of Wollongong, Australia, 2005).
     • Mårten Trolin (PhD thesis "Electronic Cash and Hierarchical Group Signatures", KTH, Sweden, 2006).
4. Produced teaching materials: two books in Estonian, slides for various courses. One book chapter on e-voting in "The Handbook of Information Security" (Wiley, 2005).
5. Member of the Steering and Program Committee of the Estonian Winter School of Computer Science (since 1998), organiser of the Estonian Theory Days (since 2002), and various extra-curriculum seminars in Estonia in 1998... 2000.
6. Organised the next mini-courses at the Helsinki University of Technology: "Provable Security" (Phil Rogaway, 2002), "Quantum Computation" (Andris Ambainis, 2002), "Design of AES" (Vincent Rijmen, 2003), at the University of Tartu: "Selected Topics in Algorithmic Game Theory" (Edith Elkind, 2005), "Software Obfuscation" (Yury Lifshits, 2006), and at the Tallinn University: "Algorithmic Game Theory" (Edith Elkind, 2010).

Impact in practice

• Governmental projects
  • Participant in time-stamping project (1997-2000; other members: Ahto Buldas, Jan Willemson, Peeter Laud, Meelis Roos, Arne Ansper, ...) that was initiated to create the necessary technical background to the Estonian Law of Digital Signatures. The law is in force since December 2000.
  • Contractor for Estonian government, electronic voting project, 2001. Member of the e-voting project, 2003.
  • Participated in Norwegian Internet voting project, 2009. We proposed the setting (specified in our Esorics 2010 publication) that will be used in Norway.
• Patent applications (both cancelled for various reasons):
  • U.S. patent application. Application No. 09,375,935 for: TIME-STAMPING WITH BINARY LINKING SCHEMES. File No.: A-66712. (Inventors Ahto Buldas, Peeter Laud, Helger Lipmaa and Jan Villemson).
  • 1 more patent application (Nokia) was withdrawn.
• Standardisation activities: my work, co-authored with Buldas et alt., on time-stamping has been under standardisation in the ISO SC27 work group. I was an active participant of the AES (Advanced Encryption Standard) process (publications [,,]).

Additional studies and research visits

1987-1990

The school of exact sciences (mathematics exercises of olympiad level, graded by university teachers).

1987-1990

Member of the Research Union of School Students (mathematics).

1989-1990

Chemistry club at the high school.

1989-1990

Training sessions for mathematics olympiads. (Lectures and laboratories by university professors etc.)

1994

DAIMI, Aarhus University, Denmark (3 months, complexity theory)

1996

DAIMI, Aarhus University, Denmark (4.5 months, complexity theory and cryptography)

1997

New Trends in Computer Science and Information Technology, Palmse (1 week)

1997

School on Natural Computation, Turku (1 week)

1998

Parallel and Quantum Computation, Palmse, Estonia (1 week)

1998

Summer School in Cryptography and Data Security, Aarhus, Denmark (1 week)

1999-2005

Estonian Winter School in Computer Science (Palmse, Estonia, à 1 week)

2000

Nevanlinna Prize Special Event, Helsinki, Finland (1 day)

2000

Tutorial "Network Security and IPsec" (J. Ioannides (AT&T) and A. Keromytis (Univ. of Pennsylvania)), Athens, Greece

2000

Tutorial "Electronic Payment Technologies" (Y. Frankel, eCash Technologies), Athens, Greece

2002

Tutorial "Constructive Applications of the Weil and Tate Pairings" (Alfred Menezes, University of Waterloo), Hyderabad, India

2004

"The State of Art in Stream Ciphers", (Brugge, Belgium, 3 days)

2005

Two-week research visit to I2R, Singapore.

2007

Two-week research visit to CUHK, Hong Kong.

Other information

• Computer experience: started active programming during the high school (assembly coding for 6502 and Z80, finished a few games and partial game development environments for two different home computers). Programmed in many programming languages (including some constructed by myself) and operating systems (including Apple DOS, CP/M, MSX DOS, MS DOS and derivatives, VMS, different Unix platforms). Most of the research is backed by actual computer implementations. Author of world fastest implementations of several block ciphers, most importantly AES, for the Pentium family of microprocessors.
• A member of the IACR (International Association for Cryptologic Research). Currently on the board of directors.
• Hobbies: playing go, reading, art movies, going out and socialising.
• Languages: Estonian (native), English (fluent), Russian (used to be fluent).

Publications

Books

1. Vello Hanson, Ahto Buldas, Tarvi Martens, Helger Lipmaa, Arne Ansper, Viljar Tulit, "Infosüsteemide turve I. Turvarisk" Küberneetika AS, 1997, 125 pages ["Security of Information Systems I.", book, in Estonian. This and the next book can be bought online at
   http://www.raamatukoi.ee/cgi-bin/kirjastus?300]
2. Vello Hanson, Ahto Buldas, Tarvi Martens, Helger Lipmaa, Arne Ansper, Viljar Tulit, "Infosüsteemide turve II. Turbetehnoloogia" Küberneetika AS, 1998, 372 pages ["Security of Information Systems II", book, in Estonian]

Chapters in Books

1. Helger Lipmaa, "Kvantarvutid", Eesti Füüsika Seltsi 9. aastaraamat, 1999, pp. 102-125 ["Quantum Computing", Ninth Annual of the Estonian Physics Society. In Estonian. Invited paper.]
2. Helger Lipmaa. Secure Electronic Voting Protocols. A chapter from The Handbook of Information Security, volume 2, pages 647-657, Hossein Bidgoli, Editor-in-Chief. John Wiley & Sons, Inc., 2005.

Edited Books and Proceedings

1. Helger Lipmaa, Heidi Pehu-Lehtonen, `Mobile security : proceedings of the Helsinki University of Technology Seminar on Network Security", Fall 2000. Espoo, Helsinki University of Technology, 2000.
2. Helger Lipmaa, Moti Yung, editors, "Inscrypt 2006", volume 4318 of LNCS, Springer, December 2006.

Thesis

1. Master thesis "Survey on the communication complexity", University of Tartu, 1995 (in Estonian)
2. PhD thesis "Secure and Efficient Time-Stamping Systems", University of Tartu, 1999.

Refereed proceedings and journals

1. Helger Lipmaa. IDEA: A cipher for multimedia architectures? In Stafford Tavares and Henk Meijer, editors, Selected Areas in Cryptography '98, volume 1556 of LNCS, pages 248-263, Kingston, Canada, 17-18 August 1998. Springer-Verlag.
2. Ahto Buldas, Peeter Laud, Helger Lipmaa, and Jan Villemson. Time-Stamping with Binary Linking Schemes. In Hugo Krawczyk, editor, Advances in Cryptology - CRYPTO '98, volume 1462 of LNCS, pages 486-501. Springer-Verlag, 1998.
3. Ahto Buldas, Helger Lipmaa, and Berry Schoenmakers. Optimally Efficient Accountable Time-Stamping. In Hideki Imai and Yulieng Zheng, editors, Public Key Cryptography '2000, volume 1751 of Lecture Notes in Computer Science, pages 293-305, Melbourne, Australia, 18-20 January 2000. Springer Verlag.
4. Kazumaro Aoki and Helger Lipmaa. Fast Implementations of AES Candidates. In Third AES Candidate Conference, New York City, USA, 13-14 April 2000.
5. Ahto Buldas, Peeter Laud, and Helger Lipmaa. Accountable Certificate Management using Undeniable Attestations. In Sushil Jajodia and Pierangela Samarati, editors, 7th ACM Conference on Computer and Communications Security, pages 9-18, Athens, Greece, 1-4 November 2000. ACM Press.
6. Helger Lipmaa and Shiho Moriai. Efficient Algorithms for Computing Differential Properties of Addition. In Mitsuru Matsui, editor, Fast Software Encryption '2001, volume 2355 of LNCS, pages 336-350, Yokohama, Japan, 2-4 April 2001. Springer-Verlag, 2002.
7. Helger Lipmaa, N. Asokan, Valtteri Niemi, Secure Vickrey Auctions without Threshold Trust. In Matt Blaze, editor, Financial Cryptography 2002, volume 2357 of LNCS, Southampton Beach, Bermuda, 11-14 March 2002. Springer-Verlag.
8. Ahto Buldas, Peeter Laud, and Helger Lipmaa. Eliminating Counterevidence with Applications to Accountable Certificate Management. Journal of Computer Security, 10(3):273-296, 2002. Special issue for the best papers of ACM CCS 2000. One of the three invited papers.
9. Helger Lipmaa. Fast Software Implementations of SC2000. In Agnes Chan and Virgil Gligor, editors, Information Security Conference 2002, volume 2433 of Lecture Notes in Computer Science, pages 63-74, São Paulo, Brazil, 30 September - 2 October 2002. Springer-Verlag.
10. Helger Lipmaa. On Optimal Hash Tree Traversal for Interval Time-Stamping. In Agnes Chan and Virgil Gligor, editors, Information Security Conference 2002, volume 2433 of LNCS, pages 357-371, São Paulo, Brazil, 30 September - 2 October 2002. Springer-Verlag.
11. Helger Lipmaa. On Differential Properties of Pseudo-Hadamard Transform and Related Mappings. In Alfred Menezes and Palash Sarkar, editors, INDOCRYPT 2002, volume 2551 of LNCS, pages 48-61, Hyderabad, India, 15-18 December 2002. Springer-Verlag.
12. Helger Lipmaa. On Diophantine Complexity and Statistical Zero-Knowledge Arguments. In Chi Sung Laih, editor, Advances on Cryptology - ASIACRYPT 2003, volume 2894 of LNCS, pages 398-415, Taipei, Taiwan, November 30-December 4 2003. Springer-Verlag.
13. Helger Lipmaa. Verifiable Homomorphic Oblivious Transfer and Private Equality Test. In Chi Sung Laih, editor, Advances on Cryptology - ASIACRYPT 2003, volume 2894 of LNCS, pages 416-433, Taipei, Taiwan, November 30-December 4 2003. Springer-Verlag.
14. Edith Elkind and Helger Lipmaa. Interleaving Cryptography and Mechanism Design: The Case of Online Auctions. In Ari Juels, editor, Financial Cryptography - Eighth International Conference, volume 3110 of Lecture Notes in Computer Science, pages 117-131, Key West, FL, USA, February 9-12 2004. Springer-Verlag.
15. Andris Ambainis, Markus Jakobsson and Helger Lipmaa. Cryptographic Randomized Response Techniques. In Feng Bao, Robert H. Deng and Jianying Zhou, editors, Public Key Cryptography 2004, volume 2947 of Lecture Notes in Computer Science, pages 425-438, Singapore, March 1-4 2004. Springer-Verlag.
16. Helger Lipmaa, Johan Wallén and Philippe Dumas. On the Additive Differential Probability of Exclusive-Or. In Bimal Roy and Willi Meier, editor, Fast Software Encryption 2004, volume 3017 of LNCS, pages 317-331, Delhi, India, February 5-7 2004. Springer-Verlag.
17. Sven Laur and Helger Lipmaa. On Private Similarity Search Protocols. In Sanna Liimatainen and Teemupekka Virtanen, editors, Proceedings of the Ninth Nordic Workshop on Secure IT Systems (NordSec 2004), pages 73-77, Espoo, Finland, November 4-5, 2004.
18. Bart Goethals, Sven Laur, Helger Lipmaa and Taneli Mielikäinen. On Private Scalar Product Computation for Privacy-Preserving Data Mining. In Choonsik Park and Seongtaek Chee, editors, The 7th Annual International Conference in Information Security and Cryptology (ICISC 2004), volume 3506 of Lecture Notes in Computer Science, pages 104-120, Seoul, Korea, December 2-3, 2004. Springer-Verlag.
19. Edith Elkind and Helger Lipmaa. Small Coalitions Cannot Manipulate Voting. In Andrew Patrick and Moti Yung, editors, Financial Cryptography and Data Security - Ninth International Conference, volume 3570 of Lecture Notes in Computer Science, pages 285-297, Roseau, The Commonwealth Of Dominica, February 28-March 3, 2005. Springer-Verlag.
20. Helger Lipmaa, Guilin Wang and Feng Bao. Designated Verifier Signature Schemes: Attacks, New Security Notions and A New Construction. In Luis Caires, Guiseppe F. Italiano, Luis Monteiro, Catuscia Palamidessi, and Moti Yung, editors, The 32nd International Colloquium on Automata, Languages and Programming, ICALP 2005, volume 3580 of LNCS, pages 459-471, Lisboa, Portugal, July 11-15, 2005. Springer-Verlag.
21. Helger Lipmaa. An Oblivious Transfer Protocol with Log-Squared Communication. In Jianying Zhou and Javier Lopez, editors, The 8th Information Security Conference (ISC'05), volume 3650 of Lecture Notes in Computer Science, pages 314-328, Singapore, September 20-23, 2005. Springer-Verlag.
22. Sven Laur, Helger Lipmaa and Taneli Mielikäinen. Private Itemset Support Counting. In Sihan Qing, Wenbo Mao and Javier Lopez, editors, Seventh International Conference on Information and Communications Security, ICICS '05, volume 3783 of Lecture Notes in Computer Science, pages 97-111, Beijing, China, December 10-13, 2005. Springer-Verlag.
23. Yong Li, Helger Lipmaa and Dingyi Pei. On Delegatability of Four Designated Verifier Signatures. In Sihan Qing, Wenbo Mao and Javier Lopez, editors, Seventh International Conference on Information and Communications Security, ICICS '05, volume 3783 of LNCS, pages 61-71, Beijing, China, December 10-13, 2005. Springer-Verlag.
24. Edith Elkind and Helger Lipmaa. Hybrid Voting Protocols and Hardness of Manipulation. In Xiaotie Deng and Dingzhu Du, editors, The 16th Annual International Symposium on Algorithms and Computation, ISAAC 2005, volume 3827 of LNCS, pages 206-215, Sanya, Hainan, China, December 19-21, 2005. Springer-Verlag.
25. Ammar Alkassar, Elena Andreeva and Helger Lipmaa. SLC: Efficient Authenticated Encryption for Short Packets. In Erik Zenner and Stefan Lucks, editors, Workshop "Kryptographie in Theorie und Praxis", part of the conference Sicherheit 2006, volume ? of ?, pages 270-278, Magdeburg, Germany, February 20-22, 2006.
26. Sven Laur, Helger Lipmaa and Taneli Mielikäinen. Cryptographically Private Support Vector Machines. In Lyle Ungar, Mark Craven, Dimitrios Gunopulos and Tina Eliassi-Rad, editors, The Twelfth ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, KDD 2006, pages 618-624, Philadelphia, USA, August 20-23, 2006. ACM.
27. Sven Laur and Helger Lipmaa. A New Protocol for Conditional Disclosure of Secrets And Its Applications. In Jonathan Katz and Moti Yung, editors, ACNS 2007, volume 4521 of LNCS, pages 207-225, Zhuhai, China, June 5-8, 2007. Springer-Verlag.
28. Philippe Dumas, Helger Lipmaa and Johan Wallén. Asymptotic Behaviour of A Non-Commutative Rational Series with A Nonnegative Linear Representation. Discrete Mathematics and Theoretical Computer Science, 9(1):247-274, October 2007.
29. Giovanni Di Crescenzo and Helger Lipmaa. Succinct NP Proofs from An Extractability Assumption. In Arnold Beckmann, Costas Dimitracopoulos and Benedikt Löwe, editors, Computability in Europe, volume 5028 of LNCS, pages 175-185, Athens, Greece, June 15-20, 2008. Springer-Verlag.
30. Helger Lipmaa. New Communication-Efficient Oblivious Transfer Protocols Based on Pairings. In Tzong-Chen Wu and Chin-Laung Lei, editors, 11th Information Security Conference, ISC 2008, volume 5222 of LNCS, pages 441-454, Taipei, Taiwan, September 15-18, 2008. Springer-Verlag.
31. Yvo Desmedt, Helger Lipmaa and Duong Hieu Phan. Hybrid Damgård Is CCA1-Secure under The DDH Assumption. In Matthew K. Franklin, Lucas Chi Kwong Hui and Duncan S. Wong, editors, The 7th International Conference on Cryptology And Network Security (CANS 2008), volume 5339 of LNCS, pages 18-30, Hong Kong, China, December 2-4, 2008. Springer-Verlag.
32. Jin Tamura, Kazukuni Kobara, Ryo Nojima, Hideki Imai and Helger Lipmaa. A note on the error of Optimized LFC Private Information Retrieval Scheme. In Hirosuke Yamamoto (?), editor, 2008 International Symposium on Information Theory and its Applications, ISITA 2008, volume ? of ?, pages ?-?, Auckland, New Zealand, December 7-10, 2008. IEEE.
33. Giovanni Di Crescenzo and Helger Lipmaa. 3-Message NP Arguments in The BPK Model with Optimal Soundness And Zero-Knowledge. In Seok-Hee Hong, Hiroshi Nagamochi and Takuro Fukunaga, editors, The 19th International Symposium on Algorithm and Computation, ISAAC 2008, volume 5369 of LNCS, pages 616-628, Gold Coast, Australia, December 15-17, 2008. Springer-Verlag.
34. Arne Ansper, Sven Heiberg, Helger Lipmaa, Tom André Øverland and Filip van Laenen. Security and Trust for the Norwegian E-voting Pilot Project E-valg 2011. In Audun Jøsang, Torleiv Maseng, and Svein J. Knapskog, editors, NordSec 2009, 2009, volume 5838 of LNCS, pages 207-222, Oslo, Norway, October 14-16, 2009. Springer-Verlag.
35. Helger Lipmaa. First CPIR Protocol with Data-Dependent Computation. In Donghoon Lee and Seokhie Hong, editors, ICISC 2009, volume 5984 of Lecture Notes in Computer Science, pages 193-210, Seoul, Korea, December 2-4, 2009. Springer-Verlag. To appear.
36. Helger Lipmaa and Bingsheng Zhang. Efficient Generalized Selective Private Function Evaluation with Applications in Biometric Authentication. In Feng Bao, Moti Yung, Dongdai Lin and Jiwu Jing, editors, Inscrypt 2009, volume 6151 of LNCS, pages 154-163, Beijing, China, December 11-15, 2009. Springer-Verlag. To appear.
37. Sven Laur and Helger Lipmaa. On the Feasibility of Consistent Computations. In Phong Q. Nguyen and David Pointcheval, editors, PKC 2010, volume 6056 of LNCS, pages 88-106, Paris, France, May 26-28, 2010. Springer-Verlag.
38. Jens Groth, Aggelos Kiayias and Helger Lipmaa. Multi-Query Computationally-Private Information Retrieval with Constant Communication Rate. In Phong Q. Nguyen and David Pointcheval, editors, PKC 2010, volume 6056 of LNCS, pages 107-123, Paris, France, May 26-28, 2010. Springer-Verlag.
39. Helger Lipmaa and Bingsheng Zhang. Two New Efficient PIR-Writing Protocols. In Jianying Zhou and Moti Yung, editors, ACNS 2010, volume 6123 of LNCS, pages 438-455, Beijing, China, June 22-25, 2010. Springer-Verlag.
40. Rafik Chaabouni, Helger Lipmaa and Abhi Shelat. Additive Combinatorics and Discrete Logarithm Based Range Protocols. In Ron Steinfeld and Philip Hawkes, editors, ACISP 2010, volume 6168 of Lecture Notes in Computer Science, pages 336-351, Sydney, Australia, July 5-7, 2010. Springer-Verlag.
41. Sven Heiberg, Helger Lipmaa, and Filip van Laenen. On E-Vote Integrity in the Case of Malicious Voter Computers. In Dimitris Gritzalis, Bart Preneel and Marianthi Theoharidou, editors, Esorics 2010, volume 6345 of LNCS, pages 373-388, Athens, Greece, September 20-22, 2010. Springer-Verlag.
42. Helger Lipmaa. On the CCA1-Security of Elgamal and Damgård's Elgamal. In Xuejia Lai and Moti Yung, editors, Inscrypt 2010, volume 6584 of Lecture Notes in Computer Science, pages 18-35, Shanghai, China, October 20-23, 2010. Springer-Verlag. To appear.

Non-refereed workshops and invited papers (with publications)

1. Helger Lipmaa, Phillip Rogaway, and David Wagner. Comments to NIST Concerning AES-modes of Operations: CTR-mode Encryption. In Symmetric Key Block Cipher Modes of Operation Workshop, Baltimore, Maryland, US, 20 October 2000. Electronic proceedings available from http://www.nist.gov/modes.
2. Masahiko Takenaka, Helger Lipmaa, Naoya Torii. The Implementation of The Block Cipher SC2000 (III). In ISEC Technical group meeting, Tohoku University, Sendai, Japan, 18-19 July 2002. In Japanese.
3. Helger Lipmaa. Statistical Zero-Knowledge Arguments: Theory and Practice. In 4th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2004), Jyväskylä, Finland, 24-28 July 2004. Invited paper

Workshops without Publication

1. Andris Ambainis, Markus Jakobsson, Helger Lipmaa. Cryptographic Randomized Response Techniques. In DIMACS/PORTIA Workshop on Privacy-Preserving Data Mining. Rutgers University, Piscataway, NJ, USA, 15-16 March 2004. Program available at http://dimacs.rutgers.edu/Workshops/Privacy/
2. Edith Elkind and Helger Lipmaa. How Hard is it to Manipulate Voting?. In DIMACS Workshop on Electronic Voting, Rutgers U, NJ, USA, 26-27 May 2004. Program available at
   http://dimacs.rutgers.edu/Workshops/Voting/
3. Edith Elkind and Helger Lipmaa. Hybrid Voting Protocols and Hardness of Manipulation. In First Spain Italy Netherlands Meeting on Game Theory, Maastricht, The Netherlands, 24-26 June 2004. Webpage at http://www.fdewb.unimaas.nl/sing/
4. Helger Lipmaa. An Oblivious Transfer Protocol with Log-Squared Communication. In The Past, Present and Future of Oblivious Transfer, Satellite workshop of the Fifth Haifa Workshop on Interdisciplinary Applications of Graph theory, Combinatorics, and Algorithms, Haifa, Israel, May 17, 2005. Webpage at http://cri.haifa.ac.il/events/2005/graph/oblivious.htm.
5. Edith Elkind and Helger Lipmaa. Hybrid Voting Protocols and Hardness of Manipulation. In 1st International Workshop on Computational Social Choice, Amsterdam, 6-8 December 2006. Webpage at http://staff.science.uva.nl/~ulle/COMSOC-2006.

Posters

1. Andris Ambainis, Markus Jakobsson, Helger Lipmaa, "Cryptographic Randomized Response Techniques", Estonian Winter School in Computer Science, Palmse, Estonia, March 3-7 2003.

Introductory Articles in Mass Media

1. Helger Lipmaa, "Turvalised virtuaalsed privaatvõrgud," Arvutimaailm 2/97, pp 6-7 ["Virtual Private Networks", a survey in Estonian.], 1997
2. Ahto Buldas, Helger Lipmaa, "Ajatemplid digitaaldokumentidel", Arvutimaailm 2/98, pp 45-47 ["Time-stamps on the digital documents", a technical survey in Estonian.]

Public Surveys, Preprints and Technical Reports (not complete)

1. Ahto Buldas, Peeter Laud, Helger Lipmaa, Jan Villemson, "Ajatempli protokollid, turvavajadused ja tehnilised nõuded", Technical Report DO-LU-X-22-1297, Küberneetika AS, 1997, 46 pages ["Timestamp protocols, security needs and technical requirements". Written by the order of Estonian Informatics Center for the work of committee preparing the legal use of electronic documents. In Estonian.]
2. Ahto Buldas, Helger Lipmaa, "Digital Signatures, Timestamps and the corresponding Infrastructure", Küberneetika AS, Technical Report 1998-21, Jan 1998, 7 pages
3. Ahto Buldas, Peeter Laud, Helger Lipmaa, Jan Villemson. Ajatemplisüsteemide teoreetilised alused. Küberneetika AS, Infotehnoloogia osakond, DO-AR-X-14-0698, 1998
4. Ahto Buldas, Peeter Laud, Alar Leibak, Helger Lipmaa, Jan Villemson, Krüptograafiliste protokollide formaalne turvaanalüüs. Küberneetika AS, Infotehnoloogia osakond, DO-AR-T-28-1298, 1998
5. Helger Lipmaa, "AES Candidates: A Survey of Implementations", Technical Report. Available from the list of submissions to the AES2 conference NIST Webpage, 8 pages, 1999.
6. Helger Lipmaa, "Security in On-Line Governance". Survey prepared under UNESCO project "Developing Telematics and Information Networks for On-Line Governance", June 1999. Available from http://www.cc.ioc.ee/training/unesco/onlinegov/security/
7. Ahto Buldas, Helger Lipmaa, Meelis Roos, Jan Villemson. Turvalised ja efektiivsed ajatemplisüsteemid. Küberneetika AS, Infotehnoloogia osakond, DO-LU-T-30-1299, 1999
8. Helger Lipmaa, "Digital Signatures and Authentication", June 1999. Updated version of a module in "Security in On-Line Governance". Available from http://www.cyber.ee/research/publications/auth/
9. Ahto Buldas, Helger Lipmaa, Jan Villemson. Avaliku võtme sertifikaatide haldus, kasutades vaidlustamatuid kehtivustõendeid. Küberneetika AS, Infotehnoloogia osakond, DO-AR-S-04-0500, 2000.
10. Ahto Buldas, Peeter Laud and Helger Lipmaa, "Accountable Certificate Management using Undeniable Attestations", Cryptology ePrint Archive, Report 2000/027, 2000. (Published in ACM CCS 2000.)
11. Helger Lipmaa, Shiho Moriai, "Efficient Algorithms for Computing Differential Properties of Addition", Cryptology ePrint Archive, Report 2001/001, 2001. (Published in FSE 2001.)
12. Helger Lipmaa, Oleg Mürk, `E-valimiste realiseerimisvõimaluste analüüs", 33 pp, April 2001. In Estonian. [`An analysis of the possibility to organise e-voting". Analysis ordered by Estonian Department of Justice. Available from the governmental webpage of E-Voting, http://www.riik.ee/evalimised/]
13. Helger Lipmaa, "New Auction Mechanism with Bid Privacy and Minimal Cognitive Cost", 17 pp, 16 August 2001. (Nokia internal report.)
14. Helger Lipmaa, "Statistical Zero-Knowledge from Diophantine Equations", Cryptology ePrint Archive, Report 2001/086, 2001. (Superseded by 2003/105.)
15. Helger Lipmaa and N. Asokan and Valtteri Niemi, "Secure Vickrey Auctions without Threshold Trust", Cryptology ePrint Archive, Report 2001/095, 2001. (Published in FC 2002.)
16. Helger Lipmaa, "On Optimal Hash Tree Traversal for Interval Time-Stamping", Cryptology ePrint Archive, Report 2002/124, 2002. (Published in ISC 2002.)
17. Edith Elkind and Helger Lipmaa, "Interleaving Cryptography and Mechanism Design: The Case of Online Auctions", Cryptology ePrint Archive, Report 2003/021, 2003. (Published in FC 2004.)
18. Andris Ambainis, Markus Jakobsson, Helger Lipmaa, "Cryptographic Randomized Response Techniques", Cryptology ePrint Archive, Report 2003/027, 2003. (Published in PKC 2004.)
19. Helger Lipmaa, "On Diophantine Complexity and Statistical Zero-Knowledge Arguments", Cryptology ePrint Archive, Report 2003/105, 2003. (Published in ASIACRYPT 2003.)
20. Helger Lipmaa, "An Oblivious-Transfer Protocol with Log-Squared Communication", Cryptology ePrint Archive, Report 2004/063, 2004.
21. Sven Laur and Helger Lipmaa, "Additive Conditional Disclosure of Secrets And Applications", Cryptology ePrint Archive, Report 2005/378, 2005.
22. Sven Laur and Helger Lipmaa, "Consistent Adaptive Two-Party Computations", Cryptology ePrint Archive, Report 2006/088, 2006.
23. Sven Laur, Helger Lipmaa and Taneli Mielikäinen. "Cryptographically Private Support Vector Machines", Cryptology ePrint Archive, Report 2006/198, 2006.
24. Emilia Käsper, Sven Laur and Helger Lipmaa. "Black-Box Knowledge Extraction Revisited: Universal Approach with Precise Bounds", Cryptology ePrint Archive, Report 2006/356, 2006.
25. Helger Lipmaa. "New Communication-Efficient Oblivious Transfer Protocols Based on Pairings", Cryptology ePrint Archive, Report 2007/133, 2007.
26. Helger Lipmaa. "Private Branching Programs: On Communication-Efficient Cryptocomputing", Cryptology ePrint Archive, Report 2008/107, 2008.
27. Helger Lipmaa. "How to Disassemble CPIR: First CPIR with Database-Dependent Computation", Cryptology ePrint Archive, Report 2009/395, 2009.
28. Rafik Chaabouni, Helger Lipmaa, and Abhi Shelat. "Additive Combinatorics and Discrete Logarithm Based Range Protocols", Cryptology ePrint Archive, Report 2009/469, 2009.
29. Sven Heiberg, Helger Lipmaa, and Filip Van Laenen. "On E-Vote Integrity in the Case of Malicious Voter Computers", Cryptology ePrint Archive, Report 2010/195, 2010.
30. Helger Lipmaa. "Progression-Free Sets and Sublinear Pairing-Based Non-Interactive Zero-Knowledge Arguments". Cryptology ePrint Archive, Report 2011/009, 2011.

Presentations

Invited Talks at Conferences/Workshops

1. How hard is it to manipulate voting? Invited talk at the VOTEID 2009 workshop, 08.09.2009, Luxembourg.
2. Critical look at Estonian E-voting protocol. Invited talk at the Swiss E-Voting Workshop 2010, 06.09.2010, Fribourg, Switzerland.

Tutorials at conferences

1. Cryptographic techniques in privacy-preserving data-mining. In ECML/PKDD 2006, 18-22.09.2006, Berlin, Germany.
2. Cryptographic techniques in privacy-preserving data-mining. In Inscrypt 2006, 29.11-01.12.2006, Beijing, China.

Paper Presentations at Conferences

1. SAC 1998 (Kingston, Canada, 1998)
2. PKC 2000 (Melbourne, Australia, 2000)
3. ACM CCS 2000 (Athens, Greece, 2000)
4. FSE 2001 (Yokohama, Japan, 2001)
5. FC 2002 (Bermuda, 2002)
6. ISC 2002 (São Paulo, 2002, presented two papers)
7. INDOCRYPT 2002 (Hyderabad, 2002)
8. ASIACRYPT 2003 (Taipei, Taiwan, 2003, presented two papers)
9. FC 2004 (Key West, FL, USA, 2004)
10. PKC 2004 (Singapore, 2004)
11. ICALP 2005 (Lisbao, Portugal, 2005)
12. ISC 2005 (Singapore, 2005)
13. ACNS 2007 (Zhuhai, China, 2007)
14. ISC 2008 (Taipei, Taiwan, 2008)
15. CANS 2008 (Hong Kong, China, 2008)
16. ISAAC 2008 (Gold Coast, Australia, 2008)
17. Esorics 2010 (Athens, Greece, 2010)
18. Inscrypt 2010 (Shanghai, China, 2010)

Other Invited Presentations

1. "Virtual Private Networks", The Second Annual Information Security Training Seminar of the Institute of Cybernetics, Tallinn, 1996.
2. "IP-level encryption," The Third Annual Information Security Training Seminar, Tallinn, 1997, Küberneetika AS Technical Report DO-ÜV-T-20-1297, 16 pages
3. "Quantum algorithms," Estonian Autumn School of Young Physicists, 04.10.98-06.10.98.
4. "Fast cryptographic algorithms on multimedia processors", The Autumn Seminar of the Institute of Cybernetics, 1998.
5. "Formal security analysis of cryptographic protocols", The Autumn Seminar of the Institute of Cybernetics, 1998.
6. "Quantum algorithms," Seminars on quantum mechanics 1998.
7. "Three-Move Identification Schemes", Cybernetica Seminars, May 23 1999, slides 36 pages
8. "Optimally Efficient Accountable Time-Stamping", The Autumn Seminar of the Institute of Cybernetics, 1999.
9. Ahto Buldas, Helger Lipmaa, "Cryptographic methods and the security of e-commerce", E-commerce seminar of Estonian Chamber of Commerce and Industry, 27.10.1999.
10. "Fast Implementations of AES Candidates", Queensland University of Technology, Brisbane, Australia, 24.01.2000.
11. "Secure and Efficient Time-Stamping Systems", University of Wollongong, Wollongong, Australia, 25.01.2000.
12. "Secure and Efficient Time-Stamping Systems", Helsinki University of Technology, Helsinki, Finland, 07.03.2000.
13. "Secure and Efficient Time-Stamping Systems", University of Latvia, Riga, Latvia, 17.03.2000.
14. "Cryptography: from theory to practice", assembly of Estonian Mathematical Society, 25.03.2000.
15. "Accountable Certificate Management", Helsinki University, Helsinki, Finland, 26.09.2000.
16. "Efficient Algorithms for Differential Probability of Addition modulo 2ⁿ and Related Problems", Helsinki University of Technology, Laboratory of Theoretical Computer Science, 14.12.2000.
17. "On Accountable Time-Stamping and Certificate Management", NTT Laboratories, Japan, 05.04.2001.
18. "Secure Vickrey Auctions without Threshold Trust", Estonian Theory Day, Roosta, Estonia, 16-17.10.2002.
19. "On Diophantine Complexity and Statistical Zero-Knowledge Arguments", Estonian Theory Day, Pedase, Estonia, 03-05.10.2003.
20. "Interleaving Cryptography and Mechanism Design: The Case of Online Auctions", Estonian Theory Day, Koke, Estonia, 30.01-01.02.2004.
21. "An Oblivious Transfer Protocol with Log-Squared Communication", Estonian Theory Day, Veskisilla, Estonia, 1-3.10.2004.
22. Invited for a research visit to Singapore, 16-31 Jan 2005. One talk: "An Oblivious Transfer Protocol with Log-Squared Communication", 25.01.2005.
23. "Designated Verifier Signatures: Attacks, New Security Notions And A Construction", Estonian Theory Day, Koke, Estonia, 04-06.02.2005.
24. "An Oblivious Transfer Protocol with Log-Squared Communication", University of Indiana at Bloomington, 14.02.2005.
25. "Designated Verifier Signatures: Attacks, New Security Notions And A Construction", National University of Singapore, Singapore, 26.09.2005.
26. "On delegatability of four designated verifier signatures", Estonian Theory Day, Viinistu, Estonia, 28.10.2005.
27. "An Oblivious Transfer Protocol with Log-Squared Communication", Xiamen University, China, 17.12.2005.
28. "Designated Verifier Signatures: Attacks, New Security Notions And A Construction", University College London, UK, 23.02.2006.
29. "Succinct NP Proofs from An Extractable-Algorithm Assumption", Estonian Theory Days, Voore, Estonia, 01.10.2006.
30. Cryptographic techniques in privacy-preserving data-mining (tutorial). In University of Bristol, UK, 22.01.2007.
31. Cryptographic techniques in privacy-preserving data-mining (tutorial). In Estonian Theory Days, UK, 28.01.2007.
32. Research visit, Chinese University of Hong Kong, March 2007 (2 weeks). Talks:
    • Cryptographic techniques in privacy-preserving data-mining (tutorial).
33. "Hybrid Damgård is CCA1-Secure", Estonian Theory Days, Estonia, 30.9.2007.
34. On Some Open Problems in Communication-Efficient Cryptocomputing, Royal Holloway, University of London, UK, 20.03.2008.
35. Research visit, Tsinghua University, China, May 12-31, 2008. Talks:
    • Private Branching Programs: On Communication-Efficient Cryptocomputing. Tsinghua, Beijing, China, 21.05.2008.
36. "Private branching programs: on communication-efficient cryptocomputing", Estonian Theory Days, Jõulumäe, Estonia, 03.10.2008.
37. Research visit, Macquarie University, Australia, Dec 18-22, 2008. Talks:
    • Private Branching Programs: On Communication-Efficient Cryptocomputing. Macquarie University, Sydney, Australia, 19.12.2008.
38. Research visit, National Technical University, Singapore, Jan 11-30, 2009. Talks:
    • Private Branching Programs: On Communication-Efficient Cryptocomputing. NTU, Singapore, 16.01.2009.
39. Additive combinatorics and discrete logarithm based range protocols. Estonian Theory Days, Mäetaguse, Estonia, 04.10.2008.
40. Multi-Query Computationally-Private Information Retrieval with Constant Communication Rate. Estonian Theory Days, Elva, Estonia, 13.06.2010.
41. On Norwegian Internet Voting Protocols. Joint Estonian-Latvian Theory Days, Rakari, Latvia, ??.10.2010.

Rump Session Presentations

1. "Efficient Algorithms for Differential Probability modulo 2ⁿ and Related Problems" (Eurocrypt 2000, joint work with Shiho Moriai)
2. "On Optimal Hash Tree Traversal" (EWSCS 2001)
3. "On Additive Differential Probability of Exclusive Or" (Eurocrypt 2003, joint work with Johan Wallén, presented by Johan)
4. "How Hard is it to Manipulate Voting?" (FC 2004, joint work with Edith Elkind, presented by Edith)

Other Presentations

1. Several presentations at the Estonian Winter School in Computer Science, 1998-1999.

Panelist

1. "E-Voting: Challenge to the Society", Tallinn, Estonia, 19.06.2003.
2. Seminar on e-voting, Tartu, Estonia, 17.05.2004. Panel leader.
3. Swiss Workshop on e-voting, Fribourg, Switzerland, 06.09.2010
4. USENIX EVT/WOTE 2011, San Francisco, CA, USA, 08-09.08.2011