Ahto Buldas

Researcher,

Co-Founder and Chief Scientist, GuardTime

Professor, Tallinn University of Technology


e-mail: ahto.buldas@guardtime.com

Curriculum Vitae:

.pdf, .tex

Selected Publications

  1. Ahto Buldas. Congruence lattice of a graph. Proc. Estonian Acad. Sci. Phys. Math., 1997, 46, 3, 155-170.
  2. Ahto Buldas and Jüri Põldre. A VLSI implementation of RSA and IDEA encryption engine. In NORCHIP'97, Tallinn 1997.
  3. Ahto Buldas, Peeter Laud, Helger Lipmaa, Jan Villemson, "Ajatempli protokollid, turvavajadused ja tehnilised nõuded," Technical Report DO-LU-X-22-1297, Cybernetica, 1997, 46 pages ["Timestamp protocols, security needs and technical requirements". Funded by Estonian Informatics Centre]
  4. Ahto Buldas. Graphs and lattice varieties. Proc. Estonian Acad. Sci. Phys. Math., 1998, 47, 2, 100-109.
  5. Ahto Buldas, Peeter Laud, Helger Lipmaa and Jan Villemson. Time-Stamping with binary linking schemes. In Advances in Cryptology - CRYPTO'98, LNCS 1462, 486-501. Springer-Verlag, 1998. .ps, .pdf, 10.1007/BFb0055749
  6. Ahto Buldas and Peeter Laud. New linking schemes for digital time-stamping. In Proceedings of The 1st International Conference on Information Security and Cryptology - ICISC'98, 3-14, Seoul, Korea, 1998. .ps, .pdf,
  7. Ahto Buldas, Helger Lipmaa and Berry Schoenmakers. Optimally efficient accountable time-stamping. In Public Key Cryptography - PKC'2000, Melbourne, Australia. LNCS 1751, 293-305. Springer-Verlag, 2000. .ps, .pdf, 10.1007/978-3-540-46588-1_20
  8. Ahto Buldas, Meelis Roos, Valdo Praust and Jan Willemson. On long-term validation of E-documents. Baltic IT-Review, 2 (17): 53-56, 2000.
  9. Ahto Buldas, Peeter Laud and Helger Lipmaa. Accountable Certificate Management using undeniable attestations. In The 7th ACM Conference on Computer and Communication Security - CCS'00, Athens, Greece. Nov. 1-4, 2000. .ps, .pdf, 10.1145/352600.352604
  10. Arne Ansper, Ahto Buldas, Meelis Roos and Jan Willemson. Efficient long-term validation of digital signatures. In Public Key Cryptography - PKC'2001, Cheju Island, Korea. Feb. 13-15, 2001. LNCS 1992, 402-415. Springer-Verlag, 2001. .ps, .pdf, 10.1007/3-540-44586-2_29
  11. Arne Ansper, Ahto Buldas, Märt Saarepera and Jan Willemson. Improving the availability of time-stamping services. In The 6th Australasian Conference on Information Security and Privacy - ACISP'2001, Sydney, Australia, July 2-4, 2001. LNCS 2119, 360-375. Springer-Verlag, 2001. .ps, .pdf, 10.1007/3-540-47719-5_29
  12. Ahto Buldas, Peeter Laud, Helger Lipmaa. Eliminating counterevidence with applications to accountable certificate management. Journal of Computer Security, v. 10, n. 3, pp. 273-296, 2002. .pdf
  13. Ahto Buldas, Meelis Roos, Jan Willemson. Undeniable replies for database queries. In H.-M. Haav, A.Kalja, eds., Proc. of the 5th International Baltic Conference On Databases and Information Systems -- Baltic DB\&IS 2002, v.2, pp.215-226. Institute of Cybernetics, Tallinn, 2002. CiteSeerX
  14. Ahto Buldas, Märt Saarepera. Electronic signature system with small number of private keys. In 2nd Annual PKI Research Workshop, pp.96-108. NIST Gaithersburg MD, USA. April 28-29, 2003. .pdf
  15. Arne Ansper, Ahto Buldas, Margus Freudenthal, Jan Willemson. Scalable and Efficient PKI for Inter-Organizational Communication. Annual Computer Security Applications Conference -- ACSAC'2003. .pdf, 10.1109/CSAC.2003.1254335
  16. Ahto Buldas and Märt Saarepera. On provably secure time-stamping schemes. In ASIACRYPT 2004, LNCS 3329, pp. 500--514. 2004. .ps, .pdf 10.1007/978-3-540-30539-2_35
  17. Ahto Buldas, Peeter Laud, Märt Saarepera, Jan Willemson. Universally composable time-stamping schemes with audit. In Information Security Conference -- ISC 2005, LNCS 3650, pp.359--373. 2005. 10.1007/11556992_26
  18. Ahto Buldas, Sven Laur. Do broken hash functions affect the security of time-stamping schemes? In 4th International Conference on Applied Cryptography and Network Security -- ACNS'06, LNCS 3989, pp. 50-65, 2006. 10.1007/11767480_4
  19. Ahto Buldas, Peeter Laud, Jaan Priisalu, Märt Saarepera, and Jan Willemson. Rational Choice of Security Measures via Multi-Parameter Attack Trees. In Critical Information Infrasturctures Security First International Workshop -- CRITIS 2006, LNCS 4347, pp. 235-248, 2006. 10.1007/11962977_19
  20. Ahto Buldas, Sven Laur. Knowledge-binding commitments with applications in time-stamping. In The International Conference on Theory and Practice of Public-Key Cryptography (PKC 2007). Beijin, China, April 16-20, 2007. LNCS 4450, pp. 150-165, 2007. 10.1007/978-3-540-71677-8_11
  21. Ahto Buldas, Triinu Mägi. Practical security analysis of e-voting systems. In the Second International Workshop on Security (IWSEC) 2007. Nara, Japan, October 29-31, 2007. LNCS 4752, pp.320-335, 2007. 10.1007/978-3-540-75651-4_22
  22. Ahto Buldas, Aivo Jürgenson. Does secure time-stamping imply collision-free hash functions? In the 1st International Conference on Provable Security (ProvSec) 2007. Wollongong, Australia, October 31-November 2, 2007. LNCS 4784, pp.138-150, 2007. 10.1007/978-3-540-75670-5_9
  23. Ahto Buldas, Margus Niitsoo. Can we construct unbounded time-stamping schemes from collision-free hash functions? In the 2nd International Conference on Provable Security (ProvSec) 2008. Shanghai, China, October 30-November 1, 2008. LNCS 5324, pp.254-267, 2008. 10.1007/978-3-540-88733-1_18
  24. Ahto Buldas, Aivo Jürgenson, Margus Niitsoo. Efficiency bounds for adversary constructions in black-box reductions. In C. Boyd and J. Gonz.alez Nieto (Eds.): ACISP 2009, LNCS 5594, pp.264-275, 2009. 10.1007/978-3-642-02620-1_19
  25. Ahto Buldas, Sven Laur, Margus Niitsoo. Oracle separation in the non-uniform model. In J.Pieprzyk and F.Zhang (Eds.): the 3rd International Conference on Provable Security (ProvSec) 2009, November 11-13, 2009, Guangzhou, China. LNCS 5848, pp. 230-244, 2009. 10.1007/978-3-642-04642-1_19
  26. Ahto Buldas, Margus Niitsoo. Optimally tight security proofs for hash-then-publish time-stamping. In: Steinfeld, R., Hawkes, P. (eds.): ACISP 2010. LNCS 6168, pp.318-335, 2010. 10.1007/978-3-642-14081-5_20
  27. Ahto Buldas, Roman Stepanenko. Upper bounds for adversaries' utility in attack trees. In: J. Grossklags and J. Walrand (Eds.): GameSec 2012, LNCS 7638, pp. 98-117, 2012. 10.1007/978-3-642-34266-0_6
  28. Ahto Buldas, Margus Niitsoo. Black-box separations and their adaptability to the non-uniform model. In: C. Boyd and L. Simpson (Eds.): ACISP 2013, LNCS 7959, pp. 152-167, 2013. 10.1007/978-3-642-39059-3_11
  29. Ahto Buldas, Risto Laanoja. Security proofs for hash tree time-stamping using hash functions with small output size. In: C. Boyd and L. Simpson (Eds.): ACISP 2013, LNCS 7959, pp. 235-250, 2013. 10.107/978-3-642-39059-3_16
  30. Ahto Buldas, Andres Kroonmaa, Risto Laanoja. Keyless signatures infrastructure: How to build global distributed hash-trees. In: H. Riis Nielson and D. Gollmann (Eds.): NordSec 2013, LNCS 8208, pp. 313-320. Springer, Heidelberg (2013) 10.1007/978-3-642-41488-6_21
  31. Arne Ansper, Ahto Buldas, Margus Freudenthal, Jan Willemson. High-performance qualified digital signatures for X-Road. In: H. Riis Nielson and D. Gollmann (Eds.): NordSec 2013, LNCS 8208, pp. 123-138. Springer Heidelberg (2013) 10.1007/978-3-642-41488-6_9
  32. Ahto Buldas, Aleksandr Lenin. New efficient utility upper bounds for the fully adaptive model of attack trees. In: S.K. Das, C. Nita-Rotaru, and M.Kantarcioglu (Eds.): GameSec 2013, LNCS 8252, pp. 192-205. Springer International Publishing Switzerland (2013) 10.1007/978-3-319-02786-9_12

Lecture Notes

Introduction to Combinatorics and Cryptography (ITX8110)

Complexity Theory (University of Tartu)

Combinatorics (University of Tartu)

Loeng "Sissejuhatus krüptograafiasse"

Seminar for Cyber Defence Students, Autumn 2012

Presentations from 2011

Loeng "Sissejuhatus andmeturbesse"