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Jan Haltermann, Manuel Töws, Felix Pauck, Cedric Richter, Heike Wehrheim, Jürgen König, Arnab Sharma, Steffen Beringer, Oleksandra Koslova, Elisabeth Schlatt (left to right) Show image information

Jan Haltermann, Manuel Töws, Felix Pauck, Cedric Richter, Heike Wehrheim, Jürgen König, Arnab Sharma, Steffen Beringer, Oleksandra Koslova, Elisabeth Schlatt (left to right)

Jan Haltermann, M.Sc. 

Address: Jan Haltermann
Paderborn University
Faculty of Electrical Engineering, Computer Science and Mathematics
Warburger Str. 100
D-33098 Paderborn, Germany
Office: O4.131

Availability (Working hours):
Monday - Friday
08:30 am until 15:30 pm Calender
Phone: +49 (0) 5251-60-1709
Fax:  +49 (0) 5251-60-3993 
Email: jfh(at)
Secretary: Elisabeth Schlatt
Phone: +49 (0) 5251-60-3764
Email: schlatt(at)
Office: O4.125



WS 2019/20           Modellierung Organization, Tutorial



Open list in Research Information System


Analyzing Data Usage in Array Programs

J.F. Haltermann, Master's thesis, 2019


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, 2018

We present CLARC (Cryptographic Library for Anonymous Reputation and Credentials), an anonymous credentials system (ACS) combined with an anonymous reputation system. Using CLARC, users can receive attribute-based credentials from issuers. They can efficiently prove that their credentials satisfy complex (access) policies in a privacy-preserving way. This implements anonymous access control with complex policies. Furthermore, CLARC is the first ACS that is combined with an anonymous reputation system where users can anonymously rate services. A user who gets access to a service via a credential, also anonymously receives a review token to rate the service. If a user creates more than a single rating, this can be detected by anyone, preventing users from spamming ratings to sway public opinion. To evaluate feasibility of our construction, we present an open-source prototype implementation.

JMCTest: Automatically Testing Inter-Method Contracts in Java

P. Börding, J.F. Haltermann, M. Jakobs, H. Wehrheim, in: Proceedings of the IFIP International Conference on Testing Software and Systems (ICTSS 2018), Springer, 2018, pp. 39--55

Over the years, Design by Contract (DbC) has evolved as a powerful concept for program documentation, testing, and verification. Contracts formally specify assertions on (mostly) object-oriented programs: pre- and postconditions of methods, class invariants, allowed call orders, etc. Missing in the long list of properties specifiable by contracts are, however, method correlations: DbC languages fall short on stating assertions relating methods. In this paper, we propose the novel concept of inter-method contract, allowing precisely for expressing method correlations.We present JMC as a language for specifying and JMCTest as a tool for dynamically checking inter-method contracts on Java programs. JMCTest fully automatically generates objects on which the contracted methods are called and the validity of the contract is checked. Using JMCTest, we detected that large Java code bases (e.g. JBoss, Java RT) frequently violate standard inter-method contracts. In comparison to other verification tools inspecting (some) inter-method contracts, JMCTest can find bugs that remain undetected by those tools.

Open list in Research Information System

Research Interest

Kooperative Softwareverifikation


The University for the Information Society