Publications

Collaboration Fintech

Project Hamilton. Conceptual Analysis

Ahto Buldas. Märt Saarepera 

The Hamilton Project, conducted by the Federal Reserve Bank of Boston together with the Massachusetts Institute of Technology Digital Currency Initiative, is a concept study on implementing central bank digital currency (CBDC). 

This report is based on the information presented in the technical paper [1] of the Hamilton project, where two possible CBDC designs are described. In Section 2, we present basic engineering principles of CBDC design. In Section 3, we analyze both designs in the framework of the engineering principles and compare them with the KSI-Cash [3] and Bitcoin [2].

Authors' version available HERE.

Academic Paper Collaboration

Zero-Knowledge in EasyCrypt

Denis Firsov, Dominique Unruh 

In: Proceedings of 36th IEEE Computer Security Foundations Symposium, CSF 2023, to appear.

Pre-print version available HERE.
Academic Paper Collaboration

Secure and Efficient Implementation of Electronic Money

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Ahto Buldas, Dirk Draheim, Märt Saarepera

In: Dang, T.K., Küng, J., Chung, T.M. (eds) Future Data and Security Engineering. Big Data, Security and Privacy, Smart City and Industry 4.0 Applications. FDSE 2022. Communications in Computer and Information Science, vol 1688. Springer, Singapore.
Academic Paper Collaboration

Towards a Foundation of Web3

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Ahto Buldas, Dirk Draheim, Mike Gault, Märt Saarepera

In: Dang, T.K., Küng, J., Chung, T.M. (eds) Future Data and Security Engineering. Big Data, Security and Privacy, Smart City and Industry 4.0 Applications. FDSE 2022. Communications in Computer and Information Science, vol 1688. Springer, Singapore.
Academic Paper Collaboration

An Ultra-Scalable Blockchain Platform for Universal Asset Tokenization: Design and Implementation

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Ahto Buldas, Dirk Draheim, Mike Gault, Risto Laanoja, Takehiko Nagumo, Märt Saarepera, Syed Attique Shah, Joosep Simm, Jamie Steiner, Tanel Tammet, Ahto Truu

In: IEEE Access, vol. 10, pp. 77284-77322, 2022.
Academic Paper Collaboration

Unsatisfiability of Comparison-Based Non-malleability for Commitments

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Denis Firsov, Sven Laur, Ekaterina Zhuchko

In: H. Seidl, Z. Liu, C. S. Pasareanu, eds., Proc. of 19th Int. Coll. on Theoretical Aspects of Computing, ICTAC 2022 (Tbilisi, Sept. 2022), v. 13572 of Lect. Notes in Comput. Sci., pp. 305-323. Springer, 2022.

Authors' version available HERE
Academic Paper Collaboration

Reflection, Rewinding, and Coin-Toss in EasyCrypt

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Denis Firsov, Dominique Unruh 

In: Proceedings of the 11th ACM SIGPLAN International Conference on Certified Programs and Proofs (CPP 2022). Association for Computing Machinery, New York, NY, USA, 166–179. 

Authors' version available HERE.

Academic Paper KSI Security

Bounded Pre-Image Awareness and the Security of Hash-Tree Keyless Signatures

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Ahto Buldas, Risto Laanoja, Peeter Laud, Ahto Truu

In: Sherman S. M. Chow, Joseph K. Liu, Lucas Chi Kwong Hui, Siu-Ming Yiu. Provable Security - 8th International Conference, ProvSec 2014, Proceedings. LNCS 8782, pp. 130-145. Springer, 2014. 

Pre-print version available HERE.
Academic Paper KSI Security

Security Proofs for Hash-Tree Time-Stamping Using Hash Functions with Small Output Size

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Ahto Buldas, Risto Laanoja

In: Colin Boyd, Leonie Simpson. Information Security and Privacy - 18th Australasian Conference, ACISP 2013, Proceedings. LNCS 7959, pp. 235-250. Springer, 2013.
Academic Paper KSI Security

Optimally Tight Security Proofs for Hash-Then-Publish Time-Stamping.

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Ahto Buldas, Margus Niitsoo

In: Ron Steinfeld, Philip Hawkes. Information Security and Privacy - 15th Australasian Conference, ACISP 2010, Proceedings. LNCS 6168, pp. 318-335. Springer, 2010.

Academic Paper KSI Security

Knowledge-Binding Commitments with Applications in Time-Stamping

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Ahto Buldas, Sven Laur

In: Okamoto T., Wang X. (eds) Public Key Cryptography – PKC 2007. PKC 2007. Lecture Notes in Computer Science, vol 4450. Springer, 2007.
Academic Paper KSI Security

Does Secure Time-Stamping Imply Collision-Free Hash Functions?

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Ahto Buldas, Aivo Jürgenson

In: Susilo W., Liu J.K., Mu Y. (eds) Provable Security. ProvSec 2007. Lecture Notes in Computer Science, vol 4784. Springer, 2007.
Academic Paper KSI Security

Do Broken Hash Functions Affect the Security of Time-Stamping Schemes?

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Ahto Buldas, Sven Laur

In: Zhou J., Yung M., Bao F. (eds) Applied Cryptography and Network Security. ACNS 2006. Lecture Notes in Computer Science, vol 3989. Springer, 2006.
Academic Paper KSI Security

Universally Composable Time-Stamping Schemes with Audit

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Ahto Buldas, Peeter Laud, Mart Saarepera, Jan Willemson

In: Zhou J., Lopez J., Deng R.H., Bao F. (eds) Information Security. ISC 2005. Lecture Notes in Computer Science, vol 3650. Springer, 2005.

Extended version available HERE.
Academic Paper KSI Security

On Provably Secure Time-Stamping Schemes

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Ahto Buldas, Märt Saarepera

In: Pil Joong Lee. Advances in Cryptology - ASIACRYPT 2004, 10th International Conference on the Theory and Application of Cryptology and Information Security, Proceedings. LNCS 3329, pp. 500-514. Springer, 2004.

Academic Paper KSI Engineering

Verifiable Multi-Party Business Process Automation

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Joosep Simm, Jamie Steiner, Ahto Truu.

In: A. Del Río Ortega, H. Leopold, F.M. Santoro. Business Process Management Workshops. BPM 2020. LNBIP 397, pp. 30-41. Springer, 2021.

Author's manuscript available HERE.
Academic Paper KSI Engineering

Keyless Signature Infrastructure and PKI: Hash-Tree Signatures in Pre- and Post-Quantum World

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Ahto Buldas, Risto Laanoja, Ahto Truu

In: International Journal of Services Technology and Management, Vol. 23, Nos. 1/2, pp. 117-130. Inderscience publishers, 2017.

Academic Paper KSI Engineering

Efficient Record-Level Keyless Signatures for Audit Logs

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Ahto Buldas, Ahto Truu, Risto Laanoja, Rainer Gerhards

In: Karin Bernsmed, Simone Fischer-Hübner. Secure IT Systems - 19th Nordic Conference, NordSec 2014, Proceedings. LNCS 8788, pp. 149-164. Springer, 2014.

Pre-print version available HERE.
Academic Paper KSI Engineering

Keyless Signatures' Infrastructure: How to Build Global Distributed Hash-Trees

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Ahto Buldas, Andres Kroonmaa, Risto Laanoja

In: Hanne Riis Nielson, Dieter Gollmann. Secure IT Systems - 18th Nordic Conference, NordSec 2013, Proceedings. LNCS 8208, pp 313-320. Springer, 2013.

Pre-print version available HERE.
Academic Paper BLT

BLT+L: Efficient Signatures from Timestamping and Endorsements

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Denis Firsov, Henri Lakk, Sven Laur, Ahto Truu

In Proceedings of the 18th International Conference on Security and Cryptography (SECRYPT), pp. 75–86, SciTePress, 2021

Pre-print version available HERE. 

Academic Paper BLT

Verified Multiple-Time Signature Scheme from One-Time Signatures and Timestamping

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Denis Firsov, Henri Lakk, Ahto Truu

In 2021 IEEE 34th Computer Security Foundations Symposium (CSF), pp. 1–13, IEEE, 2021

Pre-print version available HERE.
Code available HERE.
Academic Paper BLT

Verified Security of BLT Signature Scheme

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Denis Firsov, Ahto Buldas, Ahto Truu, Risto Laanoja

In: CPP 2020: Proceedings of the 9th ACM SIGPLAN International Conference on Certified Programs and Proofs, pp. 244–257. ACM DL, 2020.

Pre-print available HERE.
Code HERE.
Academic Paper BLT

A New Approach to Constructing Digital Signature Schemes

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Ahto Buldas, Denis Firsov, Risto Laanoja, Henri Lakk, Ahto Truu

In: Attrapadung N., Yagi T. (eds) Advances in Information and Computer Security. IWSEC 2019. Lecture Notes in Computer Science, vol 11689. Springer, 2019. 

Extended version available HERE.

Academic Paper BLT

A Blockchain-Assisted Hash-Based Signature Scheme

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Ahto Buldas, Risto Laanoja, Ahto Truu

In: Nils Gruschka. Secure IT Systems - 23rd Nordic Conference, NordSec 2018, Proceedings. LNCS 11252, pp. 138-153. Springer, 2018.

Pre-print available HERE.
Academic Paper BLT

A Server-Assisted Hash-Based Signature Scheme

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Ahto Buldas, Risto Laanoja, Ahto Truu

In: Helger Lipmaa, Aikaterini Mitrokotsa, Raimundas Matulevičius. Secure IT Systems - 22nd Nordic Conference, NordSec 2017, Proceedings. LNCS 10674, pp. 3-17. Springer, 2017.

Pre-print version available HERE.
Academic Paper Policy

The Technological Sovereignty Dilemma – and How New Technology Can Offer a Way Out

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Luukas Ilves, Anna-Maria Osula

In: European Cybersecurity Journal, Vol. 6, No. 1, 2020, pp. 24-35. 
Academic Paper Policy

Blockchain Industry, Regulations and Policy in Estonia

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Risto Hansen

In: Asian Research Policy , Vol. 9, No. 2, 2018 (special issue on Science and Technology Trends - Blockchain Industries, Regulations and Policy), pp. 45-55.
Academic Paper Collaboration

A Unifying Theory of Electronic Money and Payment Systems

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Ahto Buldas, Märt Saarepera, Jamie Steiner, Dirk Draheim  

In: TechRxiv (2021)

PDF version available HERE.

Academic Paper Collaboration

A privacy-preserving statistics marketplace using local differential privacy and blockchain: An application to smart-grid measurements sharing

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Nikos Fotiou, Iakovos Pittaras, Vasilios A. Siris, George C. Polyzos, Priit Anton

In Blockchain: Research and Applications, Vol. 2, No. 1, April 2021


Academic Paper Collaboration

SST Data Trust as a Service - Towards Secure Decentralised Management and Exchange of Space Surveillance and Tracking Data

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M. Popp, V. Rogojin, M.C.Boysan, and M. Wallum.

In 8th European Conference on Space Debris, 20-23.04.2021, vol 8/1, ESA Space Debris Office, 2021.

Whitepaper

Blockchain Receipts using History Trees

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Guardtime Whitepaper by Risto Alas and Hema Krishnamurthy, 2020

Whitepaper

Blockchain Designed for Supply Chains: Guardtime Supply Chain Framework

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Guardtime Whitepaper, 2020
Whitepaper

Shortage Alerts Engine

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Guardtime Health Whitepaper, 2020
Whitepaper

Real World Data Engine

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Guardtime Health Whitepaper, 2020
Whitepaper

Data integrity critical in securing autonomous AI

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Whitepaper by Guardtime Strategic Advisor Tony Kenyon, 2019
Whitepaper

Privacy Series: Differential Privacy in a Nutshell

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Guardtime Research whitepaper, 2019
Whitepaper

Convergence of Blockchain and Artificial Intelligence

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Guardtime Research whitepaper, 2019
Whitepaper

Guardtime Health

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Guardtime Whitepaper, 2019
Whitepaper

Enabling Multi Party Trust in the Era of 5G and Multi-Access Edge Computing

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Guardtime Whitepaper, 2019
Whitepaper

KSI and PUF - Internet of Things Authentication

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Guardtime Whitepaper, 2016
Whitepaper

KSI and SDN - Use of a globally distributed blockchain to secure SDN

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Guardtime Whitepaper, 2016
Whitepaper

KSI and Insider Threat - Combating the enemy within – an elegant mathematical approach to insider threat eradication

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Guardtime Whitepaper, 2015
Whitepaper

Attributable Networks - Truth, not Trust

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Guardtime Whitepaper, 2014
Whitepaper

Cloud Insecurity and True Accountability - Primer for CIOs on Guardtime and KSI for Attributed Networking

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Guardtime Whitepaper, 2014
Whitepaper

Internet of Things (IoT) Security - Turning Defense into Offence

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Guardtime Whitepaper, 2014