Research and Publications

My main interests in cryptography are secure communication and storage protocols, multi-party computation and blockchain protocols, and more generally the theoretical study of cryptosystems together with their applications . Beyond that, I am interested in topics in the intersection of cryptography, game theory, and theoretical computer science.

New Papers & Preprints

New pre-prints will appear shortly.

Publications

Universally Composable SNARKs with Transparent Setup without Programmable Random Oracle [ ePrint ]

Joint work with Matteo Campanelli, Michele Ciampi, Luigi Russo, and Luisa Siniscalchi.

Advances in Cryptology — CRYPTO 2025. Lecture Notes in Computer Science, Springer (to appear).

What Did Come Out of it? Analysis and Improvements of DIDComm Messaging [ ePrint ]

Joint work with Fabio Banfi and Jesus Diaz Vico.

CCS '24 — Proceedings of the 2024 ACM SIGSAC Conference on Computer and Communications Security, pp. 4732-4746, Dec 2024 . [ DOI ]

Scalable and Lightweight State-Channel Audits [ ePrint ]

Joint work with Maxim Jourenko, Dimitris Karakostas, and Mario Larangeira.

Cryptology and Network Security (CANS), 2024. Lecture Notes in Computer Science, Springer, vol. 14905 (Proceedings Part I), pp. 264–288, Oct 2024. [ DOI ]

Unlinkable Policy-Compliant Signatures for Compliant and Decentralized Anonymous Payments [ ePrint ]

Joint work with Mahdi Sedaghat and Hendrik Waldner.

Proceedings on Privacy Enhancing Technologies (PoPETS), 2024(4), pp. 226-267. [ DOI ]

This paper was also presented at the Cryptographic Tools for Blockchains (CTB) Workshop 2024.

Consensus Redux: Distributed Ledgers in the Face of Adversarial Supremacy [ ePrint ]

Joint work with Peter Gazi, Aggelos Kiayias, Alexander Russell, and Vassilis Zikas.

2024 IEEE 37th Computer Security Foundations Symposium (CSF). IEEE, pp. 143-158, Oct 2024 [ DOI ]

Updatable Policy-Compliant Signatures [ ePrint ]

Joint work with Monosij Maitra, Christian Matt, and Hendrik Waldner.

Public-Key Cryptography — PKC 2024. Lecture Notes in Computer Science, Springer, vol. 14601 (Proceedings Part I), pp. 105–132, Apr 2024. [ DOI ]

Bitcoin as a Transaction Ledger: A Composable Treatment [ ePrint ]

Joint work with Ueli Maurer, Daniel Tschudi, and Vassilis Zikas.

Journal of Cryptology - J Cryptol, 37, 18 (2024) [ DOI ]

An earlier version of this work appeared as an extended abstract in the proceedings of Crypto 2017.

Agile Cryptography: A Universally Composable Approach [ ePrint ]

Joint work with Michele Ciampi and Aggelos Kiayias.

Theory of Cryptography — TCC 2023. Lecture Notes in Computer Science, Springer, vol. 14372 (Proceedings Part IV), pp. 480–509, Nov 2023. [ DOI ]

A Composable Security Treatment of ECVRF and Batch Verifications [ ePrint (Extended Version) ]

Joint work with Peter Gazi, Inigo Querejeta-Azurmendi, and Alexander Russell.

Computer Security — ESORICS 2022. Lecture Notes in Computer Science, Springer, vol. 13556 (Proceedings Part III), pp. 22–41, Sep 2022. [ DOI ]

Policy-Compliant Signatures [ ePrint ]

Joint work with Christian Matt and Hendrik Waldner.

Theory of Cryptography — TCC 2021. Lecture Notes in Computer Science, Springer, vol. 13044 (Proceedings Part III), pp. 350–381, Nov 2021. [ DOI ]

On the (Ir)Replaceability of Global Setups, or How (Not) to Use a Global Ledger [ ePrint ]

Joint work with Julia Hesse and Vassilis Zikas.

Theory of Cryptography — TCC 2021. Lecture Notes in Computer Science, Springer, vol. 13043 (Proceedings Part II), pp. 626–657, Nov 2021. [ DOI ]

Generalized Proofs of Knowledge with Fully Dynamic Setup [ ePrint ]

Joint work with Daniel Jost and Ueli Maurer.

Theory of Cryptography — TCC 2021. Lecture Notes in Computer Science, Springer, vol. 13042 (Proceedings Part I), pp. 499–528, Nov 2021. [ DOI ]

A Rational Protocol Treatment of 51% Attacks [ ePrint ]

Joint work with Yun Lu and Vassilis Zikas.

Advances in Cryptology — CRYPTO 2021. Lecture Notes in Computer Science, Springer, vol. 12827 (Proceedings Part III), pp. 3–32, Aug 2021. [ DOI ]

This work was part of the program of the Workshop on the Theory and Practice of Blockchains 2021.

Consistency for Functional Encryption [ ePrint ]

Joint work with Aggelos Kiayias, Markulf Kohlweiss, and Hendrik Waldner.

2021 IEEE 34th Computer Security Foundations Symposium (CSF). IEEE, pp. 1-16, Jun 2021 [ DOI ]

Dynamic Ad Hoc Clock Synchronization [ ePrint (Ouroboros Chronos) ]

Joint work with Peter Gazi, Aggelos Kiayias, Alexander Russell, and Vassilis Zikas.

Advances in Cryptology — EUROCRYPT 2021. Lecture Notes in Computer Science, Springer, vol. 12698 (Proceedings Part III), pp. 399–428, Jun 2021. [ DOI ]

Revisiting (R)CCA Security and Replay Protection [ ePrint ]

Joint work with Ueli Maurer, Christopher Portmann, and Guilherme Rito.

Public-Key Cryptography — PKC 2021. Lecture Notes in Computer Science, Springer, vol. 12711 (Proceedings Part II), pp. 173–202, May 2021. [ DOI ]

Universal Composition with Global Subroutines: Capturing Global Setup within plain UC [ ePrint ]

Joint work with Ran Canetti, Julia Hesse, Björn Tackmann, and Vassilis Zikas.

Theory of Cryptography — TCC 2020. Lecture Notes in Computer Science, Springer, vol. 12552 (Proceedings Part III), pp. 1–30, Dec 2020. [ DOI ]

Security Limitations of Classical-Client Delegated Quantum Computing [ arXiv ]

Joint work with Alexandru Cojocaru, Léo Colisson, Elham Kashefi, Dominik Leichtle, Atul Mantri, Petros Wallden.

Advances in Cryptology — ASIACRYPT 2020. Lecture Notes in Computer Science, Springer, vol. 12492 (Proceedings Part II), pp. 667–696, Dec 2020. [ DOI ]

Work was presented as a poster at QCrypt 2020 and part of the program of QTurn 2020.

Ouroboros Genesis: Composable Proof-of-Stake Blockchains with Dynamic Availability [ ePrint ]

Joint work with Peter Gazi, Aggelos Kiayias, Alexander Russell, and Vassilis Zikas.

CCS '18 — Proceedings of the 2018 ACM SIGSAC Conference on Computer and Communications Security, pp. 913-930, Oct 2018. [ DOI ]

A Constructive Perspective on Signcryption Security [ ePrint ]

Joint work with Fabio Banfi and Ueli Maurer.

Security and Cryptography for Networks — SCN 2018. Lecture Notes in Computer Science, Springer, vol. 11035, pp. 102–120, Sep 2018. [ DOI ]

But Why Does it Work? A Rational Protocol Design Treatment of Bitcoin [ ePrint ]

Joint work with Juan Garay, Ueli Maurer, Daniel Tschudi, and Vassilis Zikas.

Advances in Cryptology — EUROCRYPT 2018. Lecture Notes in Computer Science, Springer, vol. 10821 (Proceedings Part II), pp. 34–65, Apr 2018. [ DOI ]

Composable and Robust Outsourced Storage [ ePrint ]

Joint work with Ueli Maurer.

Topics in Cryptology — CT-RSA 2018. Lecture Notes in Computer Science, Springer, vol. 10808, pp. 354-373, Apr 2018. [ DOI ]

On Composable Security for Digital Signatures [ ePrint ]

Joint work with Ueli Maurer and Björn Tackmann.

Public-Key Cryptography — PKC 2018. Lecture Notes in Computer Science, Springer, vol. 10769 (Proceedings Part I), pp. 494–523, Mar 2018. [ DOI ]

Strengthening Access Control Encryption [ ePrint ]

Joint work with Christian Matt and Ueli Maurer.

Advances in Cryptology — ASIACRYPT 2017. Lecture Notes in Computer Science, Springer, vol. 10624, pp. 502–532, Nov 2017. [ DOI ]

Bitcoin as a Transaction Ledger: A Composable Treatment [ ePrint ]

Joint work with Ueli Maurer, Daniel Tschudi, and Vassilis Zikas.

Advances in Cryptology — CRYPTO 2017. Lecture Notes in Computer Science, Springer, vol. 10401 (Proceedings Part I), pp. 324–356, Aug 2017. [ DOI ]

Efficiency Lower Bounds for Commit-and-Prove Constructions

Joint work with Sandro Coretti, Chen-Da Liu Zhang, and Ueli Maurer.

2017 IEEE International Symposium on Information Theory (ISIT). IEEE, pp. 1788–1792, Jun 2017. [ DOI ]

Direct Access:

BCLM17.pdf

Robust Authenticated Encryption and the Limits of Symmetric Cryptography [ ePrint ]

Joint work with Christian Matt, Ueli Maurer, Phillip Rogaway, and Björn Tackmann.

15th IMA International Conference on Cryptography and Coding — IMACC 2015. Lecture Notes in Computer Science, Springer, vol. 9496, pp. 112–129, Dec 2015. [ DOI ]

Augmented Secure Channels and the Goal of the TLS 1.3 Record Layer [ ePrint ]

Joint work with Christian Matt, Ueli Maurer, Phillip Rogaway, and Björn Tackmann.

The 9th International Conference on Provable Security — ProvSec 2015. Lecture Notes in Computer Science, Springer, vol. 9451, pp. 85–104, Nov 2015. [ DOI ]

Manuscripts and Technical Reports

On UC-secure Range Extension and Batch Verification for ECVRF [ Link ]

Joint work with Peter Gazi, Inigo Querejeta-Azurmendi, and Alexander Russell.

(A technical report that contains a careful UC treatment of practical VRF constructions. An extended abstract of this work appears at ESORICS 2022.)

A note on the equivalence of IND-CCA & INT-PTXT and IND-CCA & INT-CTXT [ ePrint ]

Joint work with Fabio Banfi and Daniel Jost. (Feb 2018)

(A technical note that contains a proof of a statement typically not covered in textbooks.)

PhD Thesis

Ideailzations of Practical Cryptographic Building Blocks

ETH Zurich, 2018 [ DOI ]

Direct Access:

thesis_christian_badertscher.pdf

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