Publications - Codes and Cryptography

A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices

J. Blömer, J. Bobolz, L.A. Porzenheim, in: 2023.

Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain

S. Hemmrich, J. Bobolz, D. Beverungen, J. Blömer, in: ECIS 2023 Research Papers, 2023.

On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC

J. Blömer, J. Bobolz, H. Bröcher, in: 2023.

Privacy-Preserving Cryptography: Attribute-Based Signatures and Updatable Credentials

F. Eidens, Privacy-Preserving Cryptography: Attribute-Based Signatures and Updatable Credentials, 2022.

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Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes

J. Bobolz, F. Eidens, R. Heitjohann, J. Fell, (2021).

Issuer-Hiding Attribute-Based Credentials

J. Bobolz, F. Eidens, S. Krenn, S. Ramacher, K. Samelin, in: Cryptology and Network Security, Springer International Publishing, Cham, 2021.

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A Complexity Theoretical Study of Fuzzy K-Means

J. Blömer, S. Brauer, K. Bujna, ACM Transactions on Algorithms 16 (2020) 1–25.

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Cryptography for the Crowd — A Study of Cryptographic Schemes with Applications to Crowd Work

N. Löken, Cryptography for the Crowd — A Study of Cryptographic Schemes with Applications to Crowd Work, 2020.

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How well do SEM algorithms imitate EM algorithms? A non-asymptotic analysis for mixture models

J. Blömer, S. Brauer, K. Bujna, D. Kuntze, Advances in Data Analysis and Classification 14 (2020) 147–173.

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Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection

J. Bobolz, F. Eidens, S. Krenn, D. Slamanig, C. Striecks, in: Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20), ACM, New York, NY, USA, 2020.

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Classification and Approximation of Geometric Location Problems

S. Brauer, Classification and Approximation of Geometric Location Problems, Paderborn, 2019.

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Complexity of single-swap heuristics for metric facility location and related problems

S. Brauer, Theoretical Computer Science 754 (2019) 88–106.

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Dynamic Searchable Encryption with Access Control

J. Blömer, N. Löken, in: 12th International Symposium on Foundations and Practice of Security, FPS 2019, Springer, 2019.

Personal Cross-Platform Reputation

J. Blömer, N. Löken, in: Security and Trust Management, STM 2019, 2019.

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Updatable Anonymous Credentials and Applications to Incentive Systems

J. Blömer, J. Bobolz, D.P. Diemert, F. Eidens, in: Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19, 2019.

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Cloud Architectures for Searchable Encryption

J. Blömer, N. Löken, in: Proceedings of the 13th International Conference on Availability, Reliability and Security, ARES 2018, ACM, New York, NY, USA, n.d., pp. 25:1--25:10.

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Coresets for Fuzzy K-Means with Applications

J. Blömer, S. Brauer, K. Bujna, in: 29th International Symposium on Algorithms and Computation (ISAAC 2018), Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik, 2018, pp. 46:1--46:12.

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Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures

J. Blömer, J. Bobolz, in: ACNS 2018 Applied Cryptography & Network Security, n.d.

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Enhanced Security of Attribute-Based Signatures

J. Blömer, F. Eidens, J. Juhnke, in: The International Conference on Cryptology And Network Security (CANS), Springer, 2018, pp. 235–255.

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Fully-Featured Anonymous Credentials with Reputation System

K. Bemmann, J. Blömer, J. Bobolz, H. Bröcher, D.P. Diemert, F. Eidens, L. Eilers, J.F. Haltermann, J. Juhnke, B. Otour, L.A. Porzenheim, S. Pukrop, E. Schilling, M. Schlichtig, M. Stienemeier, in: Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18, ACM, New York, NY, USA, n.d.

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Models and Constructions for Secure Reputation Systems

J. Juhnke, Models and Constructions for Secure Reputation Systems, Universität Paderborn, 2018.

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Practical, Anonymous, and Publicly Linkable Universally-Composable Reputation Systems

J. Blömer, F. Eidens, J. Juhnke, in: Topics in Cryptology - {CT-RSA} 2018 - The Cryptographers’ Track at the {RSA} Conference 2018, Proceedings, Springer International Publishing, Cham, 2018, pp. 470–490.

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Provably Anonymous Communication Based on Trusted Execution Environments

J. Blömer, J. Bobolz, C. Scheideler, A. Setzer, Provably Anonymous Communication Based on Trusted Execution Environments, n.d.

Voronoi Cells of Lattices with Respect to Arbitrary Norms

J. Blömer, K. Kohn, SIAM Journal on Applied Algebra and Geometry. 2 (2018) 314–338.

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Attribute-Based Encryption as a Service for Access Control in Large-Scale Organizations

J. Blömer, P. Günther, V. Krummel, N. Löken, in: Foundations and Practice of Security, Springer International Publishing, Cham, 2017, pp. 3–17.

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CCA-Security for Predicate Encryption Schemes

G. Liske, CCA-Security for Predicate Encryption Schemes, Universität Paderborn, 2017.

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Complexity of Single-Swap Heuristics for Metric Facility Location and Related Problems

S. Brauer, in: D. Fotakis, A. Pagourtzis, V.T. Paschos (Eds.), Lecture Notes in Computer Science, Springer International Publishing, Cham, 2017, pp. 116–127.

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Searchable Encryption with Access Control

N. Löken, in: Proceedings of the 12th International Conference on Availability, Reliability and Security - ARES ’17, ACM Press, 2017.

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Soft Clustering Algorithms - Theoretical and Practical Improvements

K. Bujna, Soft Clustering Algorithms - Theoretical and Practical Improvements, Universität Paderborn, 2017.

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Subtleties in Security Definitions for Predicate Encryption with Public Index

J. Blömer, G. Liske, in: Proceedings of the International Conference of Mathematical Aspects of Computer and Information Sciences (MACIS), Springer International Publishing, Cham, 2017, pp. 438–453.

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A Theoretical Analysis of the Fuzzy K-Means Problem

J. Blömer, S. Brauer, K. Bujna, in: 2016 IEEE 16th International Conference on Data Mining (ICDM), IEEE, 2016, pp. 805–810.

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Adaptive Seeding for Gaussian Mixture Models

J. Blömer, K. Bujna, in: Advances in Knowledge Discovery and Data Mining, Springer International Publishing, Cham, 2016, pp. 296–308.

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Adaptive Seeding for Gaussian Mixture Models

J. Blömer, K. Bujna, in: Advances in Knowledge Discovery and Data Mining, Springer International Publishing, Cham, 2016, pp. 296–308.

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Construction of Fully CCA-Secure Predicate Encryptions from Pair Encoding Schemes

J. Blömer, G. Liske, in: Proceedings of the CT-RSA 2016, 2016, pp. 431–447.

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Effizienz und Sicherheit paarungsbasierter Kryptographie

J. Blömer, P. Günther, Effizienz Und Sicherheit Paarungsbasierter Kryptographie, Tagungsband des 26. Fraunhofer SIT Smartcard-Workshops, 2016.

Hard-Clustering with Gaussian Mixture Models

J. Blömer, S. Brauer, K. Bujna, (2016).

Implementing Cryptographic Pairings on Accumulator Based Smart Card Architectures

P. Günther, V. Krummel, in: Mathematical Aspects of Computer and Information Sciences, Springer International Publishing, Cham, 2016, pp. 151–165.

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Physical attacks on pairing-based cryptography

P. Günther, Physical Attacks on Pairing-Based Cryptography, Universität Paderborn, 2016.

Singular Curve Point Decompression Attack

J. Blömer, P. Günther, in: 2015 Workshop on Fault Diagnosis and Tolerance in Cryptography (FDTC), IEEE, 2016.

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Theoretical Analysis of the k-Means Algorithm – A Survey

J. Blömer, C. Lammersen, M. Schmidt, C. Sohler, in: Algorithm Engineering, Springer International Publishing, Cham, 2016, pp. 81–116.

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Anonymous and Publicly Linkable Reputation Systems

J. Blömer, J. Juhnke, C. Kolb, in: Proceedings of the 18th International Conference on Financial Cryptography and Data Security (FC), 2015, pp. 478--488.

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Short Group Signatures with Distributed Traceability

J. Blömer, J. Juhnke, N. Löken, in: Proceedings of the Sixth International Conference on Mathematical Aspects of Computer and Information Sciences (MACIS), 2015, pp. 166–180.

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Voronoi Cells of Lattices with Respect to Arbitrary Norms

J. Blömer, K. Kohn, Voronoi Cells of Lattices with Respect to Arbitrary Norms, Universität Paderborn, 2015.

A Practical Second-Order Fault Attack against a Real-World Pairing Implementation

J. Blömer, R. Gomes da Silva, P. Günther, J. Krämer, J.-P. Seifert, in: Proceedings of Fault Tolerance and Diagnosis in Cryptography(FDTC), 2014, pp. 123--136.

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A Theoretical and Experimental Comparison of the EM and SEM Algorithm

J. Blömer, K. Bujna, D. Kuntze, in: 2014 22nd International Conference on Pattern Recognition, IEEE, 2014.

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Analysis of Agglomerative Clustering

M.R. Ackermann, J. Blömer, D. Kuntze, C. Sohler, Algorithmica 69 (2014).

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Constructing CCA-secure predicate encapsulation schemes from CPA-secure schemes and universal one-way hash functions

J. Blömer, G. Liske, (2014).

Tampering attacks in pairing-based cryptography

J. Blömer, P. Günther, G. Liske, in: Proceedings of Fault Tolerance and Diagnosis in Cryptography(FDTC), 2014, pp. 1--7.

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An Approach for Determining Optimal Contrast in Visual Cryptography

J. Juhnke, H. Lefmann, V. Strehl, An Approach for Determining Optimal Contrast in Visual Cryptography, Fortschritt-Berichte VDI, 2013.

Direct Chosen-Ciphertext Secure Attribute-Based Key Encapsulations without Random Oracles

J. Blömer, G. Liske, (2013).

Improved Side Channel Attacks on Pairing Based Cryptography

J. Blömer, P. Günther, G. Liske, in: Constructive Side-Channel Analysis and Secure Design, Springer Berlin Heidelberg, Berlin, Heidelberg, 2013, pp. 154–168.

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Practical algorithms for clustering and modeling large data sets - Analysis and improvements

D. Kuntze, Practical Algorithms for Clustering and Modeling Large Data Sets - Analysis and Improvements, Universität Paderborn, 2013.

Securing Critical Unattended Systems with Identity Based Cryptography - A Case Study

J. Blömer, P. Günther, V. Krummel, in: Proceedings of the 5th International Conference on Mathematical Aspects of Computer and Information Sciences (MACIS), 2013, pp. 98–105.

StreamKM++: A clustering algorithm for data streams

M.R. Ackermann, M. Märtens, C. Raupach, K. Swierkot, C. Lammersen, C. Sohler, 17 (2012).

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Turing und Kryptografie

J. Blömer, Informatik-Spektrum 35 (2012).

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Algorithms for lattice problems with respect to general norms

S. Naewe, Algorithms for Lattice Problems with Respect to General Norms, Universität Paderborn, 2011.

Hardness and Non-Approximability of Bregman Clustering Problems.

M.R. Ackermann, J. Blömer, C. Scholz, (2011).

How to Share a Secret

J. Blömer, in: Algorithms Unplugged, Springer Berlin Heidelberg, Berlin, Heidelberg, 2011, pp. 159–168.

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Solving the Closest Vector Problem with respect to Lp Norms

J. Blömer, S. Naewe, ArXiv:1104.3720 (2011).

Bregman Clustering for Separable Instances

M.R. Ackermann, J. Blömer, in: SWAT 2010, Springer Berlin Heidelberg, Berlin, Heidelberg, 2010, pp. 212–223.

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Clustering for Metric and Nonmetric Distance Measures

M.R. Ackermann, J. Blömer, C. Sohler, ACM Trans. Algorithms (2010) 59:1--59:26.

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Efficient and Compact CCA Security from Partitioned IBKEM

J. Schrieb, (2010).

Engineering self-coordinating software intensive systems

W. Schäfer, A. Trächtler, M. Birattari, J. Blömer, M. Dorigo, G. Engels, R. O’Grady, M. Platzner, F. Rammig, W. Reif, in: Proceedings of the FSE/SDP Workshop on Future of Software Engineering Research - FoSER ’10, ACM Press, 2010.

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On the initialization of dynamic models for speech features

A. Krueger, V. Leutnant, R. Haeb-Umbach, M. Ackermann, J. Blömer, Proc. of ITG Fachtagung Sprachkommunikation. ITG, Bochum, Germany (2010).

Algorithms for the Bregman k-Median Problem

M.R. Ackermann, Algorithms for the Bregman K-Median Problem, Universität Paderborn, 2009.

Coresets and Approximate Clustering for Bregman Divergences

M.R. Ackermann, J. Blömer, in: Proceedings of the Twentieth Annual ACM-SIAM Symposium on Discrete Algorithms, Society for Industrial and Applied Mathematics, Philadelphia, PA, 2009, pp. 1088–1097.

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Sampling methods for shortest vectors, closest vectors and successive minima

J. Blömer, S. Naewe, Theoretical Computer Science 410 (2009) 1648–1665.

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Three-Valued Spotlight Abstractions

J. Schrieb, H. Wehrheim, D. Wonisch, in: FM 2009: Formal Methods, Springer Berlin Heidelberg, Berlin, Heidelberg, 2009, pp. 106–122.

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Reliable Evidence of Data Integrity from an Untrusted Storage Service

C. Stern, P. Adelt, V. Krummel, M.R. Ackermann, in: Fourth International Conference on Networking and Services (Icns 2008), IEEE, 2008.

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A Probabilistic Zero-Test for Expressions Involving Roots of Rational Numbers

J. Blömer, in: Algorithms — ESA’ 98, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 151–162.

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Analysis of Countermeasures Against Access Driven Cache Attacks on AES

J. Blömer, V. Krummel, in: Selected Areas in Cryptography, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 96–109.

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Cryptanalysis of Unbalanced RSA with Small CRT-Exponent

A. May, in: Advances in Cryptology — CRYPTO 2002, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 242–256.

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Dimension Reduction Methods for Convolution Modular Lattices

A. May, J.H. Silverman, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 110–125.

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Key Revocation with Interval Cover Families

J. Blömer, A. May, in: Selected Areas in Cryptography, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 325–341.

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Low Secret Exponent RSA Revisited

J. Blömer, A. May, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, Berlin, Heidelberg, 2007, pp. 4–19.

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Sampling methods for shortest vectors, closest vectors and successive minima

J. Blömer, S. Naewe, in: Proceedings of the 34th ICALP, Springer Verlag, 2007, pp. 65–77.

Tamper Resistance of AES -- Models, Attacks and Countermeasures

V. Krummel, Tamper Resistance of AES -- Models, Attacks and Countermeasures, Universität Paderborn, 2007.

Fault Based Collision Attacks on AES

J. Blömer, V. Krummel, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, Berlin, Heidelberg, 2006, pp. 106–120.

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Randomness and Secrecy - A Brief Introduction

J. Blömer, Journal of Universal Computer Science (J.UCS) (2006) 654--671.

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Sign Change Fault Attacks on Elliptic Curve Cryptosystems

J. Blömer, M. Otto, J.-P. Seifert, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, Berlin, Heidelberg, 2006, pp. 36–52.

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Wagner’s Attack on a Secure CRT-RSA Algorithm Reconsidered

J. Blömer, M. Otto, in: Lecture Notes in Computer Science, Springer Berlin Heidelberg, Berlin, Heidelberg, 2006, pp. 13–23.

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A Tool Kit for Finding Small Roots of Bivariate Polynomials over the Integers

J. Blömer, A. May, in: EUROCRYPT 2005, Springer Berlin Heidelberg, Berlin, Heidelberg, 2005, pp. 251–267.

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Fault Attacks and Countermeasures

M. Otto, Fault Attacks and Countermeasures, Universität Paderborn, 2005.

Partial Key Exposure Attacks on RSA up to Full Size Exponents

M. Ernst, E. Jochemsz, A. May, B. de Weger, in: EUROCRYPT 2005, Springer Berlin Heidelberg, Berlin, Heidelberg, 2005, pp. 371–386.

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A Generalized Wiener Attack on RSA

J. Blömer, A. May, in: Public Key Cryptography – PKC 2004, Springer Berlin Heidelberg, Berlin, Heidelberg, 2004, pp. 1–13.

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A new CRT-RSA algorithm secure against bellcore attacks

J. Blömer, M. Otto, J.-P. Seifert, in: Proceedings of the 10th ACM Conference on Computer and Communication Security - CCS ’03, ACM Press, 2004.

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Computing the RSA Secret Key Is Deterministic Polynomial Time Equivalent to Factoring

A. May, in: Advances in Cryptology – CRYPTO 2004, Springer Berlin Heidelberg, Berlin, Heidelberg, 2004, pp. 213–219.

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Provably Secure Masking of AES

J. Blömer, J. Guajardo, V. Krummel, in: Selected Areas in Cryptography, Springer Berlin Heidelberg, Berlin, Heidelberg, 2004, pp. 69–83.

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Secret Exponent Attacks on RSA-type Schemes with Moduli N=p^{r}q

A. May, in: Public Key Cryptography – PKC 2004, Springer Berlin Heidelberg, Berlin, Heidelberg, 2004, pp. 218–230.

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Fault Based Cryptanalysis of the Advanced Encryption Standard (AES)

J. Blömer, J.-P. Seifert, in: Financial Cryptography, Springer Berlin Heidelberg, Berlin, Heidelberg, 2003, pp. 162–181.

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New Partial Key Exposure Attacks on RSA

J. Blömer, A. May, in: Advances in Cryptology - CRYPTO 2003, Springer Berlin Heidelberg, Berlin, Heidelberg, 2003, pp. 27–43.

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New RSA Vulnerabilities Using Lattice Reduction Methods

A. May, New RSA Vulnerabilities Using Lattice Reduction Methods, Universität Paderborn, 2003.

Computing sums of radicals in polynomial time

J. Blömer, in: [1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science, IEEE Comput. Soc. Press, 2002.

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Denesting by Bounded Degree Radicals

J. Blömer, Algorithmica 28 (2002) 2–15.

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Priority encoding transmission

A. Albanese, J. Blömer, J. Edmonds, M. Luby, M. Sudan, IEEE Transactions on Information Theory 42 (2002) 1737–1744.

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Priority encoding transmission

A. Albanese, J. Blömer, J. Edmonds, M. Luby, M. Sudan, in: Proceedings 35th Annual Symposium on Foundations of Computer Science, IEEE Comput. Soc. Press, 2002.

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Closest Vectors, Successive Minima, and Dual HKZ-Bases of Lattices

J. Blömer, in: Automata, Languages and Programming, Springer Berlin Heidelberg, Berlin, Heidelberg, 2000, pp. 248–259.

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On the complexity of computing short linearly independent vectors and short bases in a lattice

J. Blömer, J.-P. Seifert, in: Proceedings of the Thirty-First Annual ACM Symposium on Theory of Computing - STOC ’99, ACM Press, 1999.

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A lower bound for a class of graph based loss resilient codes

J. Blömer, B. Trachsler, Technical Report/Departement of Computer Science, ETH Zürich (1998).

Denesting by bounded degree radicals

J. Blömer, in: Algorithms — ESA ’97, Springer Berlin Heidelberg, Berlin, Heidelberg, 1997, pp. 53–63.

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The rank of sparse random matrices over finite fields

J. Blömer, R. Karp, E. Welzl, Random Structures \& Algorithms (1997) 407–419.

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An XOR-based erasure-resilient coding scheme

J. Blömer, M. Kalfane, R. Karp, M. Karpinski, M. Luby, D. Zuckerman, An XOR-Based Erasure-Resilient Coding Scheme, Berkeley, USA, 1995.

Approximate matching of polygonal shapes

H. Alt, B. Behrends, J. Blömer, Annals of Mathematics and Artificial Intelligence 13 (1995).

On Kummer theory and the number of roots of unity in radical extensions of Q

J. Blömer, On Kummer Theory and the Number of Roots of Unity in Radical Extensions of Q, Technical Report, Freie Universität Berlin, Fachbereich Mathematik und Informatik, 1993.

How to denest Ramanujan's nested radicals

J. Blömer, in: Proceedings., 33rd Annual Symposium on Foundations of Computer Science, IEEE, 1992.

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Resemblance and symmetries of geometric patterns

H. Alt, J. Blömer, in: Data Structures and Efficient Algorithms, Springer Berlin Heidelberg, Berlin, Heidelberg, 1992, pp. 1–24.

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Simplifying Expressions Involving Radicals

J. Blömer, Simplifying Expressions Involving Radicals, PhD thesis, Freie Universität Berlin, Fachbereich Mathematik und Informatik, 1992.

Approximate matching of polygonal shapes (extended abstract)

H. Alt, B. Behrends, J. Blömer, in: Proceedings of the Seventh Annual Symposium on Computational Geometry - SCG ’91, ACM Press, 1991.

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Computing sums of radicals in polynomial time

J. Blömer, in: Proceedings 32nd Annual Symposium of Foundations of Computer Science, IEEE Comput. Soc. Press, 1991.

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Approximation of convex polygons

H. Alt, J. Blömer, H. Wagener, in: Automata, Languages and Programming, Springer-Verlag, Berlin/Heidelberg, 1990, pp. 703–716.

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