Krzysztof Pietrzak

According to our database, Krzysztof Pietrzak authored at least 116 papers between 2003 and 2024.

Collaborative distances:

• Dijkstra number of three.
• Erdős number of three.

2024

Deniability in Automated Contact Tracing: Impossibilities and Possibilities.

Christoph U. Günther, Krzysztof Pietrzak

Proc. Priv. Enhancing Technol., 2024

Watermarkable and Zero-Knowledge Verifiable Delay Functions from any Proof of Exponentiation.

Charlotte Hoffmann, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2024

Fully Automated Selfish Mining Analysis in Efficient Proof Systems Blockchains.

Krishnendu Chatterjee, Amirali Ebrahim-Zadeh, Mehrdad Karrabi, Krzysztof Pietrzak, Michelle Yeo, Dorde Zikelic

IACR Cryptol. ePrint Arch., 2024

Trapdoor Memory-Hard Functions.

Benedikt Auerbach, Christoph U. Günther, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2024

The Cost of Maintaining Keys in Dynamic Groups with Applications to Multicast Encryption and Group Messaging.

Michael Anastos, Benedikt Auerbach, Mirza Ahad Baig, Miguel Cueto Noval, Matthew Kwan, Guillermo Pascual-Perez, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2024

2023

Certifying Giant Nonprimes.

Charlotte Hoffmann, Pavel Hubácek, Chethan Kamath, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2023

Random Oracle Combiners: Breaking the Concatenation Barrier for Collision-Resistance.

Yevgeniy Dodis, Niels Ferguson, Eli Goldin, Peter Hall, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2023

Efficiently Testable Circuits without Conductivity.

Mirza Ahad Baig, Suvradip Chakraborty, Stefan Dziembowski, Malgorzata Galazka, Tomasz Lizurej, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2023

On the Cost of Post-Compromise Security in Concurrent Continuous Group-Key Agreement.

Benedikt Auerbach, Miguel Cueto Noval, Guillermo Pascual-Perez, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2023

2022

Practical Statistically-Sound Proofs of Exponentiation in any Group.

Charlotte Hoffmann, Pavel Hubácek, Chethan Kamath, Karen Klein, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2022

Efficiently Testable Circuits.

Mirza Ahad Baig, Suvradip Chakraborty, Stefan Dziembowski, Malgorzata Galazka, Tomasz Lizurej, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2022

CoCoA: Concurrent Continuous Group Key Agreement.

Joël Alwen, Benedikt Auerbach, Miguel Cueto Noval, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak, Michael Walter

IACR Cryptol. ePrint Arch., 2022

Coffee: Fast Healing Concurrent Continuous Group Key Agreement for Decentralized Group Messaging.

Joël Alwen, Benedikt Auerbach, Miguel Cueto Noval, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2022

Wiser: Increasing Throughput in Payment Channel Networks with Transaction Aggregation.

Samarth Tiwari, Michelle Yeo, Zeta Avarikioti, Iosif Salem, Krzysztof Pietrzak, Stefan Schmid

Proceedings of the 4th ACM Conference on Advances in Financial Technologies, 2022

2021

Limits on the Adaptive Security of Yao's Garbling.

Chethan Kamath, Karen Klein, Krzysztof Pietrzak, Daniel Wichs

IACR Cryptol. ePrint Arch., 2021

On the Cost of Adaptivity in Graph-Based Games.

Chethan Kamath, Karen Klein, Krzysztof Pietrzak, Michael Walter

IACR Cryptol. ePrint Arch., 2021

On Treewidth, Separators and Yao's Garbling.

Chethan Kamath, Karen Klein, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2021

Trojan-Resilience without Cryptography.

Suvradip Chakraborty, Stefan Dziembowski, Malgorzata Galazka, Tomasz Lizurej, Krzysztof Pietrzak, Michelle Yeo

IACR Cryptol. ePrint Arch., 2021

HIDE & SEEK: Privacy-Preserving Rebalancing on Payment Channel Networks.

Zeta Avarikioti, Krzysztof Pietrzak, Iosif Salem, Stefan Schmid, Samarth Tiwari, Michelle Yeo

IACR Cryptol. ePrint Arch., 2021

Route Discovery in Private Payment Channel Networks.

Zeta Avarikioti, Mahsa Bastankhah, Mohammad Ali Maddah-Ali, Krzysztof Pietrzak, Jakub Svoboda, Michelle Yeo

IACR Cryptol. ePrint Arch., 2021

Grafting Key Trees: Efficient Key Management for Overlapping Groups.

Joël Alwen, Benedikt Auerbach, Mirza Ahad Baig, Miguel Cueto, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak, Michael Walter

IACR Cryptol. ePrint Arch., 2021

The Cost of Adaptivity in Security Games on Graphs.

Chethan Kamath, Karen Klein, Krzysztof Pietrzak, Michael Walter

Proceedings of the Theory of Cryptography - 19th International Conference, 2021

Keep the Dirt: Tainted TreeKEM, Adaptively and Actively Secure Continuous Group Key Agreement.

Karen Klein, Guillermo Pascual-Perez, Michael Walter, Chethan Kamath, Margarita Capretto, Miguel Cueto, Ilia Markov, Michelle Yeo, Joël Alwen, Krzysztof Pietrzak

Proceedings of the 42nd IEEE Symposium on Security and Privacy, 2021

LightPIR: Privacy-Preserving Route Discovery for Payment Channel Networks.

Krzysztof Pietrzak, Iosif Salem, Stefan Schmid, Michelle Yeo

Proceedings of the IFIP Networking Conference, 2021

2020

Delayed Authentication: Preventing Replay and Relay Attacks in Private Contact Tracing.

Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2020

Inverse-Sybil Attacks in Automated Contact Tracing.

Benedikt Auerbach, Suvradip Chakraborty, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak, Michael Walter, Michelle Yeo

IACR Cryptol. ePrint Arch., 2020

2019

PPAD-Hardness via Iterated Squaring Modulo a Composite.

Arka Rai Choudhuri, Pavel Hubácek, Chethan Kamath, Krzysztof Pietrzak, Alon Rosen, Guy N. Rothblum

IACR Cryptol. ePrint Arch., 2019

Keep the Dirt: Tainted TreeKEM, an Efficient and Provably Secure Continuous Group Key Agreement Protocol.

Joël Alwen, Margarita Capretto, Miguel Cueto, Chethan Kamath, Karen Klein, Guillermo Pascual-Perez, Krzysztof Pietrzak, Michael Walter

IACR Cryptol. ePrint Arch., 2019

Reversible Proofs of Sequential Work.

Hamza Abusalah, Chethan Kamath, Karen Klein, Krzysztof Pietrzak, Michael Walter

IACR Cryptol. ePrint Arch., 2019

Finding a Nash Equilibrium Is No Easier Than Breaking Fiat-Shamir.

Arka Rai Choudhuri, Pavel Hubácek, Chethan Kamath, Krzysztof Pietrzak, Alon Rosen, Guy N. Rothblum

Electron. Colloquium Comput. Complex., 2019

2018

Non-Malleable Codes.

Stefan Dziembowski, Krzysztof Pietrzak, Daniel Wichs

J. ACM, 2018

Simple Verifiable Delay Functions.

Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2018

Proofs of Catalytic Space.

Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2018

Adaptively Secure Proxy Re-encryption.

Georg Fuchsbauer, Chethan Kamath, Karen Klein, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2018

Simple Proofs of Sequential Work.

Bram Cohen, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2018

Sustained Space Complexity.

Joël Alwen, Jeremiah Blocki, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2018

2017

Efficient Authentication from Hard Learning Problems.

Eike Kiltz, Krzysztof Pietrzak, Daniele Venturi, David Cash, Abhishek Jain

J. Cryptol., 2017

Be Adaptive, Avoid Overcommitting.

Zahra Jafargholi, Chethan Kamath, Karen Klein, Ilan Komargodski, Krzysztof Pietrzak, Daniel Wichs

IACR Cryptol. ePrint Arch., 2017

Beyond Hellman's Time-Memory Trade-Offs with Applications to Proofs of Space.

Hamza Abusalah, Joël Alwen, Bram Cohen, Danylo Khilko, Krzysztof Pietrzak, Leonid Reyzin

IACR Cryptol. ePrint Arch., 2017

Non-Uniform Attacks Against Pseudoentropy.

Krzysztof Pietrzak, Maciej Skorski

Proceedings of the 44th International Colloquium on Automata, Languages, and Programming, 2017

2016

The Exact Security of PMAC.

Peter Gazi, Krzysztof Pietrzak, Michal Rybár

IACR Trans. Symmetric Cryptol., 2016

Pseudoentropy: Lower-bounds for Chain rules and Transformations.

Krzysztof Pietrzak, Maciej Skorski

IACR Cryptol. ePrint Arch., 2016

A Quasipolynomial Reduction for Generalized Selective Decryption on Trees.

Georg Fuchsbauer, Zahra Jafargholi, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2016

Position-Based Cryptography and Multiparty Communication Complexity.

Joshua Brody, Stefan Dziembowski, Sebastian Faust, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2016

On the Memory-Hardness of Data-Independent Password-Hashing Functions.

Joël Alwen, Peter Gazi, Chethan Kamath, Karen Klein, Georg Osang, Krzysztof Pietrzak, Leonid Reyzin, Michal Rolínek, Michal Rybár

IACR Cryptol. ePrint Arch., 2016

Scrypt is Maximally Memory-Hard.

Joël Alwen, Binyi Chen, Krzysztof Pietrzak, Leonid Reyzin, Stefano Tessaro

IACR Cryptol. ePrint Arch., 2016

On the Complexity of Scrypt and Proofs of Space in the Parallel Random Oracle Model.

Joël Alwen, Binyi Chen, Chethan Kamath, Vladimir Kolmogorov, Krzysztof Pietrzak, Stefano Tessaro

IACR Cryptol. ePrint Arch., 2016

Depth-Robust Graphs and Their Cumulative Memory Complexity.

Joël Alwen, Jeremiah Blocki, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2016

A counterexample to the chain rule for conditional HILL entropy.

Stephan Krenn, Krzysztof Pietrzak, Akshay Wadia, Daniel Wichs

Comput. Complex., 2016

Standard Security Does Imply Security Against Selective Opening for Markov Distributions.

Georg Fuchsbauer, Felix Heuer, Eike Kiltz, Krzysztof Pietrzak

Proceedings of the Theory of Cryptography - 13th International Conference, 2016

2015

Condensed Unpredictability.

Maciej Skorski, Alexander Golovnev, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2015

The Chain Rule for HILL Pseudoentropy, Revisited.

Krzysztof Pietrzak, Maciej Skorski

IACR Cryptol. ePrint Arch., 2015

Spacemint: A Cryptocurrency Based on Proofs of Space.

Sunoo Park, Krzysztof Pietrzak, Albert Kwon, Joël Alwen, Georg Fuchsbauer, Peter Gazi

IACR Cryptol. ePrint Arch., 2015

New Realizations of Somewhere Statistically Binding Hashing and Positional Accumulators.

Tatsuaki Okamoto, Krzysztof Pietrzak, Brent Waters, Daniel Wichs

IACR Cryptol. ePrint Arch., 2015

Simple Chosen-Ciphertext Security from Low-Noise LPN.

Eike Kiltz, Daniel Masny, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2015

Standard Security Does Imply Security Against Selective Opening for Markov Distributions.

Felix Heuer, Eike Kiltz, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2015

Generic Security of NMAC and HMAC with Input Whitening.

Peter Gazi, Krzysztof Pietrzak, Stefano Tessaro

IACR Cryptol. ePrint Arch., 2015

Tight Bounds for Keyed Sponges and Truncated CBC.

Peter Gazi, Krzysztof Pietrzak, Stefano Tessaro

IACR Cryptol. ePrint Arch., 2015

Offline Witness Encryption.

Hamza Abusalah, Georg Fuchsbauer, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2015

Key-Homomorphic Constrained Pseudorandom Functions.

Abhishek Banerjee, Georg Fuchsbauer, Chris Peikert, Krzysztof Pietrzak, Sophie Stevens

IACR Cryptol. ePrint Arch., 2015

The Exact PRF Security of Truncation: Tight Bounds for Keyed Sponges and Truncated CBC.

Peter Gazi, Krzysztof Pietrzak, Stefano Tessaro

Proceedings of the Advances in Cryptology - CRYPTO 2015, 2015

2014

Robust Multi-Property Combiners for Hash Functions.

Marc Fischlin, Anja Lehmann, Krzysztof Pietrzak

J. Cryptol., 2014

The Exact PRF-Security of NMAC and HMAC.

Peter Gazi, Krzysztof Pietrzak, Michal Rybár

IACR Cryptol. ePrint Arch., 2014

Adaptive Security of Constrained PRFs.

Georg Fuchsbauer, Momchil Konstantinov, Krzysztof Pietrzak, Vanishree Rao

IACR Cryptol. ePrint Arch., 2014

Efficient Zero-Knowledge Proofs for Commitments from Learning With Errors over Rings.

Fabrice Benhamouda, Stephan Krenn, Vadim Lyubashevsky, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2014

Constrained PRFs for Unbounded Inputs.

Hamza Abusalah, Georg Fuchsbauer, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2014

2013

A Closer Look at HMAC.

Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2013

How to Fake Auxiliary Input.

Dimitar Jetchev, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2013

Proofs of Space.

Stefan Dziembowski, Sebastian Faust, Vladimir Kolmogorov, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2013

Key Derivation Without Entropy Waste.

Yevgeniy Dodis, Krzysztof Pietrzak, Daniel Wichs

IACR Cryptol. ePrint Arch., 2013

Learning with Rounding, Revisited: New Reduction, Properties and Applications.

Joël Alwen, Stephan Krenn, Krzysztof Pietrzak, Daniel Wichs

IACR Cryptol. ePrint Arch., 2013

A Counterexample to the Chain Rule for Conditional HILL Entropy - And What Deniable Encryption Has to Do with It.

Stephan Krenn, Krzysztof Pietrzak, Akshay Wadia

Proceedings of the Theory of Cryptography - 10th Theory of Cryptography Conference, 2013

Digital Signatures with Minimal Overhead from Indifferentiable Random Invertible Functions.

Eike Kiltz, Krzysztof Pietrzak, Mario Szegedy

Proceedings of the Advances in Cryptology - CRYPTO 2013, 2013

2012

Parallel Repetition of Computationally Sound Protocols Revisited.

Krzysztof Pietrzak, Douglas Wikström

J. Cryptol., 2012

Digital Signatures with Minimal Overhead.

Eike Kiltz, Krzysztof Pietrzak, Mario Szegedy

IACR Cryptol. ePrint Arch., 2012

Message Authentication, Revisited.

Yevgeniy Dodis, Eike Kiltz, Krzysztof Pietrzak, Daniel Wichs

IACR Cryptol. ePrint Arch., 2012

Commitments and Efficient Zero-Knowledge Proofs from Hard Learning Problems.

Abhishek Jain, Stephan Krenn, Krzysztof Pietrzak, Aris Tentes

IACR Cryptol. ePrint Arch., 2012

Lossy Functions Do Not Amplify Well.

Krzysztof Pietrzak, Alon Rosen, Gil Segev

Proceedings of the Theory of Cryptography - 9th Theory of Cryptography Conference, 2012

Subspace LWE.

Krzysztof Pietrzak

Proceedings of the Theory of Cryptography - 9th Theory of Cryptography Conference, 2012

Hardness Preserving Constructions of Pseudorandom Functions.

Abhishek Jain, Krzysztof Pietrzak, Aris Tentes

Proceedings of the Theory of Cryptography - 9th Theory of Cryptography Conference, 2012

Cryptography from Learning Parity with Noise.

Krzysztof Pietrzak

Proceedings of the SOFSEM 2012: Theory and Practice of Computer Science, 2012

Lapin: An Efficient Authentication Protocol Based on Ring-LPN.

Stefan Heyse, Eike Kiltz, Vadim Lyubashevsky, Christof Paar, Krzysztof Pietrzak

Proceedings of the Fast Software Encryption - 19th International Workshop, 2012

Practical Leakage-Resilient Symmetric Cryptography.

Sebastian Faust, Krzysztof Pietrzak, Joachim Schipper

Proceedings of the Cryptographic Hardware and Embedded Systems - CHES 2012, 2012

Commitments and Efficient Zero-Knowledge Proofs from Learning Parity with Noise.

Abhishek Jain, Stephan Krenn, Krzysztof Pietrzak, Aris Tentes

Proceedings of the Advances in Cryptology - ASIACRYPT 2012, 2012

2011

Tamper-Proof Circuits: How to Trade Leakage for Tamper-Resilience.

Sebastian Faust, Krzysztof Pietrzak, Daniele Venturi

IACR Cryptol. ePrint Arch., 2011

Leftover Hash Lemma, Revisited.

Boaz Barak, Yevgeniy Dodis, Hugo Krawczyk, Olivier Pereira, Krzysztof Pietrzak, François-Xavier Standaert, Yu Yu

IACR Cryptol. ePrint Arch., 2011

Parallel Repetition for Leakage Resilience Amplification Revisited.

Abhishek Jain, Krzysztof Pietrzak

Proceedings of the Theory of Cryptography - 8th Theory of Cryptography Conference, 2011

2010

An Efficient Parallel Repetition Theorem.

Johan Håstad, Rafael Pass, Douglas Wikström, Krzysztof Pietrzak

Proceedings of the Theory of Cryptography, 7th Theory of Cryptography Conference, 2010

Leakage-Resilient Pseudorandom Functions and Side-Channel Attacks on Feistel Networks.

Yevgeniy Dodis, Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2010

Leakage Resilient ElGamal Encryption.

Eike Kiltz, Krzysztof Pietrzak

Proceedings of the Advances in Cryptology - ASIACRYPT 2010, 2010

2009

Leakage-Resilient Signatures.

Sebastian Faust, Eike Kiltz, Krzysztof Pietrzak, Guy N. Rothblum

IACR Cryptol. ePrint Arch., 2009

A Leakage-Resilient Mode of Operation.

Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2009

On the Security of Padding-Based Encryption Schemes - or - Why We Cannot Prove OAEP Secure in the Standard Model.

Eike Kiltz, Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2009

2008

A New Randomness Extraction Paradigm for Hybrid Encryption.

Eike Kiltz, Krzysztof Pietrzak, Martijn Stam, Moti Yung

IACR Cryptol. ePrint Arch., 2008

Leakage-Resilient Cryptography in the Standard Model.

Stefan Dziembowski, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2008

Weak Pseudorandom Functions in Minicrypt.

Krzysztof Pietrzak, Johan Sjödin

Proceedings of the Automata, Languages and Programming, 35th International Colloquium, 2008

Robust Multi-property Combiners for Hash Functions Revisited.

Marc Fischlin, Anja Lehmann, Krzysztof Pietrzak

Proceedings of the Automata, Languages and Programming, 35th International Colloquium, 2008

Leakage-Resilient Cryptography.

Stefan Dziembowski, Krzysztof Pietrzak

Proceedings of the 49th Annual IEEE Symposium on Foundations of Computer Science, 2008

A New Mode of Operation for Block Ciphers and Length-Preserving MACs.

Yevgeniy Dodis, Krzysztof Pietrzak, Prashant Puniya

Proceedings of the Advances in Cryptology, 2008

Compression from Collisions, or Why CRHF Combiners Have a Long Output.

Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2008

2007

Intrusion-Resilient Secret Sharing.

Stefan Dziembowski, Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2007

Improving the Security of MACs Via Randomized Message Preprocessing.

Yevgeniy Dodis, Krzysztof Pietrzak

Proceedings of the Fast Software Encryption, 14th International Workshop, 2007

Range Extension for Weak PRFs; The Good, the Bad, and the Ugly.

Krzysztof Pietrzak, Johan Sjödin

Proceedings of the Advances in Cryptology, 2007

2006

Indistinguishability and composition of random systems.

Krzysztof Pietrzak

PhD thesis, 2006

Non-Trivial Black-Box Combiners for Collision-Resistant Hash-Functions don't Exist.

Krzysztof Pietrzak

IACR Cryptol. ePrint Arch., 2006

Indistinguishability Amplification.

Ueli Maurer, Krzysztof Pietrzak, Renato Renner

IACR Cryptol. ePrint Arch., 2006

Luby-Rackoff Ciphers from Weak Round Functions?

Ueli Maurer, Yvonne Anne Oswald, Krzysztof Pietrzak, Johan Sjödin

IACR Cryptol. ePrint Arch., 2006

Separating Sources for Encryption and Secret Sharing.

Yevgeniy Dodis, Krzysztof Pietrzak, Bartosz Przydatek

Proceedings of the Theory of Cryptography, Third Theory of Cryptography Conference, 2006

A Tight Bound for EMAC.

Krzysztof Pietrzak

Proceedings of the Automata, Languages and Programming, 33rd International Colloquium, 2006

Composition Implies Adaptive Security in Minicrypt.

Krzysztof Pietrzak

Proceedings of the Advances in Cryptology - EUROCRYPT 2006, 25th Annual International Conference on the Theory and Applications of Cryptographic Techniques, St. Petersburg, Russia, May 28, 2006

2005

Composition Does Not Imply Adaptive Security.

Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2005

On the Generic Insecurity of the Full Domain Hash.

Yevgeniy Dodis, Roberto Oliveira, Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2005

Improved Security Analyses for CBC MACs.

Mihir Bellare, Krzysztof Pietrzak, Phillip Rogaway

Proceedings of the Advances in Cryptology, 2005

2004

Composition of Random Systems: When Two Weak Make One Strong.

Ueli M. Maurer, Krzysztof Pietrzak

Proceedings of the Theory of Cryptography, First Theory of Cryptography Conference, 2004

2003

On the parameterized complexity of the fixed alphabet shortest common supersequence and longest common subsequence problems.

Krzysztof Pietrzak

J. Comput. Syst. Sci., 2003

The Security of Many-Round Luby-Rackoff Pseudo-Random Permutations.

Ueli M. Maurer, Krzysztof Pietrzak

Proceedings of the Advances in Cryptology, 2003