--- _id: '44855' abstract: - lang: eng text: Market transactions are subject to information asymmetry about the delivered value proposition, causing transaction costs and adverse market effects among buyers and sellers. Information systems research has investigated how review systems can reduce information asymmetry in business-to-consumer markets. However, these systems cannot be readily applied to business-to-business markets, are vulnerable to manipulation, and suffer from conceptual weak spots since they use textual data or star ratings. Building on design science research, we conceptualize a new class of reputation systems based on monetary-based payments as quantitative ratings for each transaction stored on a blockchain. Using cryptography, we show that our system assures content confidentiality so that buyers can share and sell their ratings selectively, establishing a reputation ecosystem. Our prescriptive insights advance the design of reputation systems and offer new paths to understanding the antecedents, dynamics, and consequences to reduce information asymmetry in B2B transactions. author: - first_name: Simon full_name: Hemmrich, Simon id: '83557' last_name: Hemmrich - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Daniel full_name: Beverungen, Daniel id: '59677' last_name: Beverungen - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer citation: ama: 'Hemmrich S, Bobolz J, Beverungen D, Blömer J. Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain. In: ECIS 2023 Research Papers. ; 2023.' apa: Hemmrich, S., Bobolz, J., Beverungen, D., & Blömer, J. (2023). Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain. ECIS 2023 Research Papers. ECIS 2023. bibtex: '@inproceedings{Hemmrich_Bobolz_Beverungen_Blömer_2023, title={Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain}, booktitle={ECIS 2023 Research Papers}, author={Hemmrich, Simon and Bobolz, Jan and Beverungen, Daniel and Blömer, Johannes}, year={2023} }' chicago: Hemmrich, Simon, Jan Bobolz, Daniel Beverungen, and Johannes Blömer. “Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain.” In ECIS 2023 Research Papers, 2023. ieee: S. Hemmrich, J. Bobolz, D. Beverungen, and J. Blömer, “Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain,” presented at the ECIS 2023, 2023. mla: Hemmrich, Simon, et al. “Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain.” ECIS 2023 Research Papers, 2023. short: 'S. Hemmrich, J. Bobolz, D. Beverungen, J. Blömer, in: ECIS 2023 Research Papers, 2023.' conference: name: ECIS 2023 date_created: 2023-05-16T08:31:27Z date_updated: 2023-05-23T10:12:32Z ddc: - '330' department: - _id: '7' - _id: '64' - _id: '19' - _id: '526' extern: '1' file: - access_level: closed content_type: application/pdf creator: jbobolz date_created: 2023-05-23T10:11:03Z date_updated: 2023-05-23T10:11:03Z file_id: '45209' file_name: A_Blockchain_Based_Reputation_Ecosystem_for_Business___Payments_as_Ratings.pdf file_size: 958740 relation: main_file success: 1 file_date_updated: 2023-05-23T10:11:03Z has_accepted_license: '1' language: - iso: eng main_file_link: - url: https://aisel.aisnet.org/ecis2023_rp/344 project: - _id: '1' name: 'SFB 901: SFB 901' - _id: '4' name: 'SFB 901 - C: SFB 901 - Project Area C' - _id: '13' name: 'SFB 901 - C1: SFB 901 - Subproject C1' publication: ECIS 2023 Research Papers status: public title: Designing Business Reputation Ecosystems — A Method for Issuing and Trading Monetary Ratings on a Blockchain type: conference user_id: '27207' year: '2023' ... --- _id: '45901' author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens - first_name: Tibor full_name: Jager, Tibor id: '64669' last_name: Jager - first_name: Paul full_name: Kramer, Paul id: '64594' last_name: Kramer citation: ama: 'Blömer J, Bobolz J, Eidens F, Jager T, Kramer P. Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems. In: Haake C-J, Meyer auf der Heide F, Platzner M, Wachsmuth H, Wehrheim H, eds. On-The-Fly Computing -- Individualized IT-Services in Dynamic Markets. Vol 412. Verlagsschriftenreihe des Heinz Nixdorf Instituts. Heinz Nixdorf Institut, Universität Paderborn; 2023:237-246. doi:10.5281/zenodo.8068755' apa: Blömer, J., Bobolz, J., Eidens, F., Jager, T., & Kramer, P. (2023). Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems. In C.-J. Haake, F. Meyer auf der Heide, M. Platzner, H. Wachsmuth, & H. Wehrheim (Eds.), On-The-Fly Computing -- Individualized IT-services in dynamic markets (Vol. 412, pp. 237–246). Heinz Nixdorf Institut, Universität Paderborn. https://doi.org/10.5281/zenodo.8068755 bibtex: '@inbook{Blömer_Bobolz_Eidens_Jager_Kramer_2023, place={Paderborn}, series={Verlagsschriftenreihe des Heinz Nixdorf Instituts}, title={Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems}, volume={412}, DOI={10.5281/zenodo.8068755}, booktitle={On-The-Fly Computing -- Individualized IT-services in dynamic markets}, publisher={Heinz Nixdorf Institut, Universität Paderborn}, author={Blömer, Johannes and Bobolz, Jan and Eidens, Fabian and Jager, Tibor and Kramer, Paul}, editor={Haake, Claus-Jochen and Meyer auf der Heide, Friedhelm and Platzner, Marco and Wachsmuth, Henning and Wehrheim, Heike}, year={2023}, pages={237–246}, collection={Verlagsschriftenreihe des Heinz Nixdorf Instituts} }' chicago: 'Blömer, Johannes, Jan Bobolz, Fabian Eidens, Tibor Jager, and Paul Kramer. “Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems.” In On-The-Fly Computing -- Individualized IT-Services in Dynamic Markets, edited by Claus-Jochen Haake, Friedhelm Meyer auf der Heide, Marco Platzner, Henning Wachsmuth, and Heike Wehrheim, 412:237–46. Verlagsschriftenreihe Des Heinz Nixdorf Instituts. Paderborn: Heinz Nixdorf Institut, Universität Paderborn, 2023. https://doi.org/10.5281/zenodo.8068755.' ieee: 'J. Blömer, J. Bobolz, F. Eidens, T. Jager, and P. Kramer, “Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems,” in On-The-Fly Computing -- Individualized IT-services in dynamic markets, vol. 412, C.-J. Haake, F. Meyer auf der Heide, M. Platzner, H. Wachsmuth, and H. Wehrheim, Eds. Paderborn: Heinz Nixdorf Institut, Universität Paderborn, 2023, pp. 237–246.' mla: Blömer, Johannes, et al. “Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems.” On-The-Fly Computing -- Individualized IT-Services in Dynamic Markets, edited by Claus-Jochen Haake et al., vol. 412, Heinz Nixdorf Institut, Universität Paderborn, 2023, pp. 237–46, doi:10.5281/zenodo.8068755. short: 'J. Blömer, J. Bobolz, F. Eidens, T. Jager, P. Kramer, in: C.-J. Haake, F. Meyer auf der Heide, M. Platzner, H. Wachsmuth, H. Wehrheim (Eds.), On-The-Fly Computing -- Individualized IT-Services in Dynamic Markets, Heinz Nixdorf Institut, Universität Paderborn, Paderborn, 2023, pp. 237–246.' date_created: 2023-07-07T08:41:44Z date_updated: 2023-07-07T11:13:37Z ddc: - '004' department: - _id: '7' doi: 10.5281/zenodo.8068755 editor: - first_name: Claus-Jochen full_name: Haake, Claus-Jochen last_name: Haake - first_name: Friedhelm full_name: Meyer auf der Heide, Friedhelm last_name: Meyer auf der Heide - first_name: Marco full_name: Platzner, Marco last_name: Platzner - first_name: Henning full_name: Wachsmuth, Henning last_name: Wachsmuth - first_name: Heike full_name: Wehrheim, Heike last_name: Wehrheim file: - access_level: open_access content_type: application/pdf creator: florida date_created: 2023-07-07T08:41:35Z date_updated: 2023-07-07T11:13:37Z file_id: '45902' file_name: T2-Chapter-SFB-Buch-Final.pdf file_size: 5944790 relation: main_file file_date_updated: 2023-07-07T11:13:37Z has_accepted_license: '1' intvolume: ' 412' language: - iso: eng oa: '1' page: 237-246 place: Paderborn project: - _id: '1' grant_number: '160364472' name: 'SFB 901: SFB 901: On-The-Fly Computing - Individualisierte IT-Dienstleistungen in dynamischen Märkten ' - _id: '82' name: 'SFB 901 - T: SFB 901 - Project Area T' - _id: '84' name: 'SFB 901 - T2: SFB 901 -Subproject T2' publication: On-The-Fly Computing -- Individualized IT-services in dynamic markets publisher: Heinz Nixdorf Institut, Universität Paderborn series_title: Verlagsschriftenreihe des Heinz Nixdorf Instituts status: public title: Practical Cryptograhic Techniques for Secure and Privacy-Preserving Customer Loyalty Systems type: book_chapter user_id: '477' volume: 412 year: '2023' ... --- _id: '35014' author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Henrik full_name: Bröcher, Henrik id: '41047' last_name: Bröcher citation: ama: 'Blömer J, Bobolz J, Bröcher H. On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC. In: ; 2023.' apa: Blömer, J., Bobolz, J., & Bröcher, H. (2023). On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC. TCC 2023, Taipeh, Taiwan. bibtex: '@inproceedings{Blömer_Bobolz_Bröcher_2023, title={On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC}, author={Blömer, Johannes and Bobolz, Jan and Bröcher, Henrik}, year={2023} }' chicago: Blömer, Johannes, Jan Bobolz, and Henrik Bröcher. “On the Impossibility of Surviving (Iterated) Deletion of Weakly Dominated Strategies in Rational MPC,” 2023. ieee: J. Blömer, J. Bobolz, and H. Bröcher, “On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC,” presented at the TCC 2023, Taipeh, Taiwan, 2023. mla: Blömer, Johannes, et al. On the Impossibility of Surviving (Iterated) Deletion of Weakly Dominated Strategies in Rational MPC. 2023. short: 'J. Blömer, J. Bobolz, H. Bröcher, in: 2023.' conference: end_date: 2023-12-02 location: Taipeh, Taiwan name: TCC 2023 start_date: 2023-11-29 date_created: 2022-12-28T16:02:11Z date_updated: 2023-09-07T10:01:00Z department: - _id: '34' - _id: '64' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2022/1762 oa: '1' project: - _id: '1' grant_number: '160364472' name: 'SFB 901: SFB 901' - _id: '4' name: 'SFB 901 - C: SFB 901 - Project Area C' - _id: '13' name: 'SFB 901 - C1: SFB 901 - Subproject C1' status: public title: On the impossibility of surviving (iterated) deletion of weakly dominated strategies in rational MPC type: conference user_id: '41047' year: '2023' ... --- _id: '43458' author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Laurens Alexander full_name: Porzenheim, Laurens Alexander id: '47434' last_name: Porzenheim citation: ama: 'Blömer J, Bobolz J, Porzenheim LA. A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices. In: ; 2023.' apa: Blömer, J., Bobolz, J., & Porzenheim, L. A. (2023). A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices. Asiacrypt 2023, Guangzhou, China. bibtex: '@inproceedings{Blömer_Bobolz_Porzenheim_2023, title={A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices}, author={Blömer, Johannes and Bobolz, Jan and Porzenheim, Laurens Alexander}, year={2023} }' chicago: Blömer, Johannes, Jan Bobolz, and Laurens Alexander Porzenheim. “A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices,” 2023. ieee: J. Blömer, J. Bobolz, and L. A. Porzenheim, “A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices,” presented at the Asiacrypt 2023, Guangzhou, China, 2023. mla: Blömer, Johannes, et al. A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices. 2023. short: 'J. Blömer, J. Bobolz, L.A. Porzenheim, in: 2023.' conference: end_date: 2023-12-08 location: Guangzhou, China name: Asiacrypt 2023 start_date: 2023-12-04 date_created: 2023-04-12T08:18:41Z date_updated: 2023-09-07T09:53:26Z department: - _id: '64' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2023/464 oa: '1' project: - _id: '1' grant_number: '160364472' name: 'SFB 901: SFB 901' - _id: '13' name: 'SFB 901 - C1: SFB 901 - Subproject C1' - _id: '4' name: 'SFB 901 - C: SFB 901 - Project Area C' status: public title: A Generic Construction of an Anonymous Reputation System and Instantiations from Lattices type: conference user_id: '47434' year: '2023' ... --- _id: '26645' author: - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens - first_name: Raphael full_name: Heitjohann, Raphael last_name: Heitjohann - first_name: Jeremy full_name: Fell, Jeremy last_name: Fell citation: ama: 'Bobolz J, Eidens F, Heitjohann R, Fell J. Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes. Published online 2021.' apa: 'Bobolz, J., Eidens, F., Heitjohann, R., & Fell, J. (2021). Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes. IACR eprint.' bibtex: '@article{Bobolz_Eidens_Heitjohann_Fell_2021, title={Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes}, publisher={IACR eprint}, author={Bobolz, Jan and Eidens, Fabian and Heitjohann, Raphael and Fell, Jeremy}, year={2021} }' chicago: 'Bobolz, Jan, Fabian Eidens, Raphael Heitjohann, and Jeremy Fell. “Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes.” IACR eprint, 2021.' ieee: 'J. Bobolz, F. Eidens, R. Heitjohann, and J. Fell, “Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes.” IACR eprint, 2021.' mla: 'Bobolz, Jan, et al. Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes. IACR eprint, 2021.' short: J. Bobolz, F. Eidens, R. Heitjohann, J. Fell, (2021). date_created: 2021-10-21T07:51:32Z date_updated: 2022-11-18T09:38:42Z department: - _id: '64' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2021/961 oa: '1' project: - _id: '4' name: SFB 901 - Project Area C - _id: '82' name: SFB 901 - Project Area T - _id: '84' name: SFB 901 -Subproject T2 - _id: '1' name: 'SFB 901: SFB 901' - _id: '13' name: 'SFB 901 - C1: SFB 901 - Subproject C1' publisher: IACR eprint status: public title: 'Cryptimeleon: A Library for Fast Prototyping of Privacy-Preserving Cryptographic Schemes' type: preprint user_id: '477' year: '2021' ... --- _id: '29566' author: - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens - first_name: Stephan full_name: Krenn, Stephan last_name: Krenn - first_name: Sebastian full_name: Ramacher, Sebastian last_name: Ramacher - first_name: Kai full_name: Samelin, Kai last_name: Samelin citation: ama: 'Bobolz J, Eidens F, Krenn S, Ramacher S, Samelin K. Issuer-Hiding Attribute-Based Credentials. In: Cryptology and Network Security. Springer International Publishing; 2021. doi:10.1007/978-3-030-92548-2_9' apa: Bobolz, J., Eidens, F., Krenn, S., Ramacher, S., & Samelin, K. (2021). Issuer-Hiding Attribute-Based Credentials. Cryptology and Network Security. https://doi.org/10.1007/978-3-030-92548-2_9 bibtex: '@inproceedings{Bobolz_Eidens_Krenn_Ramacher_Samelin_2021, place={Cham}, title={Issuer-Hiding Attribute-Based Credentials}, DOI={10.1007/978-3-030-92548-2_9}, booktitle={Cryptology and Network Security}, publisher={Springer International Publishing}, author={Bobolz, Jan and Eidens, Fabian and Krenn, Stephan and Ramacher, Sebastian and Samelin, Kai}, year={2021} }' chicago: 'Bobolz, Jan, Fabian Eidens, Stephan Krenn, Sebastian Ramacher, and Kai Samelin. “Issuer-Hiding Attribute-Based Credentials.” In Cryptology and Network Security. Cham: Springer International Publishing, 2021. https://doi.org/10.1007/978-3-030-92548-2_9.' ieee: 'J. Bobolz, F. Eidens, S. Krenn, S. Ramacher, and K. Samelin, “Issuer-Hiding Attribute-Based Credentials,” 2021, doi: 10.1007/978-3-030-92548-2_9.' mla: Bobolz, Jan, et al. “Issuer-Hiding Attribute-Based Credentials.” Cryptology and Network Security, Springer International Publishing, 2021, doi:10.1007/978-3-030-92548-2_9. short: 'J. Bobolz, F. Eidens, S. Krenn, S. Ramacher, K. Samelin, in: Cryptology and Network Security, Springer International Publishing, Cham, 2021.' date_created: 2022-01-27T13:00:21Z date_updated: 2022-01-27T13:02:23Z department: - _id: '7' - _id: '64' doi: 10.1007/978-3-030-92548-2_9 language: - iso: eng place: Cham project: - _id: '1' name: 'SFB 901: SFB 901' - _id: '4' name: 'SFB 901 - C: SFB 901 - Project Area C' - _id: '13' name: 'SFB 901 - C1: SFB 901 - Subproject C1' publication: Cryptology and Network Security publication_identifier: isbn: - '9783030925475' - '9783030925482' issn: - 0302-9743 - 1611-3349 publication_status: published publisher: Springer International Publishing status: public title: Issuer-Hiding Attribute-Based Credentials type: conference user_id: '27207' year: '2021' ... --- _id: '16487' author: - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens - first_name: Stephan full_name: Krenn, Stephan last_name: Krenn - first_name: Daniel full_name: Slamanig, Daniel last_name: Slamanig - first_name: Christoph full_name: Striecks, Christoph last_name: Striecks citation: ama: 'Bobolz J, Eidens F, Krenn S, Slamanig D, Striecks C. Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection. In: Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20),. New York, NY, USA: ACM; 2020. doi:10.1145/3320269.3384769' apa: 'Bobolz, J., Eidens, F., Krenn, S., Slamanig, D., & Striecks, C. (2020). Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection. In Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20),. New York, NY, USA: ACM. https://doi.org/10.1145/3320269.3384769' bibtex: '@inproceedings{Bobolz_Eidens_Krenn_Slamanig_Striecks_2020, place={New York, NY, USA}, title={Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection}, DOI={10.1145/3320269.3384769}, booktitle={Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20),}, publisher={ACM}, author={Bobolz, Jan and Eidens, Fabian and Krenn, Stephan and Slamanig, Daniel and Striecks, Christoph}, year={2020} }' chicago: 'Bobolz, Jan, Fabian Eidens, Stephan Krenn, Daniel Slamanig, and Christoph Striecks. “Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection.” In Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20),. New York, NY, USA: ACM, 2020. https://doi.org/10.1145/3320269.3384769.' ieee: J. Bobolz, F. Eidens, S. Krenn, D. Slamanig, and C. Striecks, “Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection,” in Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20), Taiwan, 2020. mla: Bobolz, Jan, et al. “Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection.” Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20), ACM, 2020, doi:10.1145/3320269.3384769. short: '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.' conference: location: Taiwan name: ASIA CCS'20 date_created: 2020-04-09T10:00:29Z date_updated: 2022-01-06T06:52:51Z ddc: - '000' department: - _id: '64' doi: 10.1145/3320269.3384769 file: - access_level: closed content_type: application/pdf creator: feidens date_created: 2020-04-09T09:59:03Z date_updated: 2020-04-09T09:59:03Z file_id: '16488' file_name: main.pdf file_size: 553623 relation: main_file success: 1 file_date_updated: 2020-04-09T09:59:03Z has_accepted_license: '1' language: - iso: eng license: https://creativecommons.org/publicdomain/zero/1.0/ main_file_link: - open_access: '1' url: https://eprint.iacr.org/2020/382 oa: '1' place: New York, NY, USA project: - _id: '1' name: SFB 901 - _id: '84' name: SFB 901 -Subproject T2 - _id: '82' name: SFB 901 - Project Area T publication: Proceedings of the 15th ACM Asia Conference on Computer and Communications Security (ASIA CCS ’20), publisher: ACM status: public title: Privacy-Preserving Incentive Systems with Highly Efficient Point-Collection type: conference user_id: '477' year: '2020' ... --- _id: '13904' abstract: - lang: eng text: In this paper, we introduce updatable anonymous credential systems (UACS) and use them to construct a new privacy-preserving incentive system. In a UACS, a user holding a credential certifying some attributes can interact with the corresponding issuer to update his attributes. During this, the issuer knows which update function is run, but does not learn the user's previous attributes. Hence the update process preserves anonymity of the user. One example for a class of update functions are additive updates of integer attributes, where the issuer increments an unknown integer attribute value v by some known value k. This kind of update is motivated by an application of UACS to incentive systems. Users in an incentive system can anonymously accumulate points, e.g. in a shop at checkout, and spend them later, e.g. for a discount. author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Denis Pascal full_name: Diemert, Denis Pascal id: '44071' last_name: Diemert - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens citation: ama: 'Blömer J, Bobolz J, Diemert DP, Eidens F. Updatable Anonymous Credentials and Applications to Incentive Systems. In: Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19. Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19. ; 2019. doi:10.1145/3319535.3354223' apa: Blömer, J., Bobolz, J., Diemert, D. P., & Eidens, F. (2019). Updatable Anonymous Credentials and Applications to Incentive Systems. Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19. 26th ACM Conference on Computer and Communications Security, London. https://doi.org/10.1145/3319535.3354223 bibtex: '@inproceedings{Blömer_Bobolz_Diemert_Eidens_2019, series={Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19}, title={Updatable Anonymous Credentials and Applications to Incentive Systems}, DOI={10.1145/3319535.3354223}, booktitle={Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19}, author={Blömer, Johannes and Bobolz, Jan and Diemert, Denis Pascal and Eidens, Fabian}, year={2019}, collection={Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19} }' chicago: Blömer, Johannes, Jan Bobolz, Denis Pascal Diemert, and Fabian Eidens. “Updatable Anonymous Credentials and Applications to Incentive Systems.” In Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19. Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19, 2019. https://doi.org/10.1145/3319535.3354223. ieee: 'J. Blömer, J. Bobolz, D. P. Diemert, and F. Eidens, “Updatable Anonymous Credentials and Applications to Incentive Systems,” presented at the 26th ACM Conference on Computer and Communications Security, London, 2019, doi: 10.1145/3319535.3354223.' mla: Blömer, Johannes, et al. “Updatable Anonymous Credentials and Applications to Incentive Systems.” Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS ’19, 2019, doi:10.1145/3319535.3354223. short: '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.' conference: end_date: 2019-11-15 location: London name: 26th ACM Conference on Computer and Communications Security start_date: 2019-11-11 date_created: 2019-10-18T08:09:44Z date_updated: 2023-01-10T10:25:27Z ddc: - '006' department: - _id: '7' - _id: '64' doi: 10.1145/3319535.3354223 file: - access_level: closed content_type: application/pdf creator: jbobolz date_created: 2019-10-18T08:07:49Z date_updated: 2019-10-18T08:07:49Z file_id: '13907' file_name: full_eprinted_v2.pdf file_size: 838949 relation: main_file file_date_updated: 2019-10-18T08:07:49Z has_accepted_license: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2019/169.pdf oa: '1' project: - _id: '1' name: SFB 901 - _id: '4' name: SFB 901 - Project Area C - _id: '13' name: SFB 901 - Subproject C1 publication: Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS '19 series_title: Proceedings of the 2019 ACM SIGSAC Conference on Computer and Communications Security - CCS '19 status: public title: Updatable Anonymous Credentials and Applications to Incentive Systems type: conference user_id: '25078' year: '2019' ... --- _id: '3265' abstract: - lang: eng text: "We present CLARC (Cryptographic Library for Anonymous Reputation and Credentials), an anonymous credentials system (ACS) combined with an anonymous reputation system.\r\n\r\nUsing 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.\r\n\r\nFurthermore, 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.\r\n\r\nTo evaluate feasibility of our construction, we present an open-source prototype implementation." author: - first_name: Kai full_name: Bemmann, Kai last_name: Bemmann - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Henrik full_name: Bröcher, Henrik id: '41047' last_name: Bröcher - first_name: Denis Pascal full_name: Diemert, Denis Pascal id: '44071' last_name: Diemert - first_name: Fabian full_name: Eidens, Fabian id: '25078' last_name: Eidens - first_name: Lukas full_name: Eilers, Lukas last_name: Eilers - first_name: Jan Frederik full_name: Haltermann, Jan Frederik id: '44413' last_name: Haltermann - first_name: Jakob full_name: Juhnke, Jakob id: '48090' last_name: Juhnke - first_name: Burhan full_name: Otour, Burhan last_name: Otour - first_name: Laurens Alexander full_name: Porzenheim, Laurens Alexander id: '47434' last_name: Porzenheim - first_name: Simon full_name: Pukrop, Simon last_name: Pukrop - first_name: Erik full_name: Schilling, Erik last_name: Schilling - first_name: Michael full_name: Schlichtig, Michael id: '32312' last_name: Schlichtig - first_name: Marcel full_name: Stienemeier, Marcel last_name: Stienemeier citation: ama: 'Bemmann K, Blömer J, Bobolz J, et al. Fully-Featured Anonymous Credentials with Reputation System. In: Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18. New York, NY, USA: ACM. doi:10.1145/3230833.3234517' apa: 'Bemmann, K., Blömer, J., Bobolz, J., Bröcher, H., Diemert, D. P., Eidens, F., … Stienemeier, M. (n.d.). Fully-Featured Anonymous Credentials with Reputation System. In Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18. New York, NY, USA: ACM. https://doi.org/10.1145/3230833.3234517' bibtex: '@inproceedings{Bemmann_Blömer_Bobolz_Bröcher_Diemert_Eidens_Eilers_Haltermann_Juhnke_Otour_et al., place={New York, NY, USA}, title={Fully-Featured Anonymous Credentials with Reputation System}, DOI={10.1145/3230833.3234517}, booktitle={Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18}, publisher={ACM}, author={Bemmann, Kai and Blömer, Johannes and Bobolz, Jan and Bröcher, Henrik and Diemert, Denis Pascal and Eidens, Fabian and Eilers, Lukas and Haltermann, Jan Frederik and Juhnke, Jakob and Otour, Burhan and et al.} }' chicago: 'Bemmann, Kai, Johannes Blömer, Jan Bobolz, Henrik Bröcher, Denis Pascal Diemert, Fabian Eidens, Lukas Eilers, et al. “Fully-Featured Anonymous Credentials with Reputation System.” In Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18. New York, NY, USA: ACM, n.d. https://doi.org/10.1145/3230833.3234517.' ieee: K. Bemmann et al., “Fully-Featured Anonymous Credentials with Reputation System,” in Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18, Hamburg, Germany. mla: Bemmann, Kai, et al. “Fully-Featured Anonymous Credentials with Reputation System.” Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES ’18, ACM, doi:10.1145/3230833.3234517. short: '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.' conference: end_date: 2018-08-30 location: Hamburg, Germany name: ARES 2018 - SECPID start_date: 2018-08-27 date_created: 2018-06-14T11:19:29Z date_updated: 2022-01-06T06:59:07Z ddc: - '000' department: - _id: '64' doi: 10.1145/3230833.3234517 file: - access_level: closed content_type: application/pdf creator: feidens date_created: 2018-11-08T10:17:39Z date_updated: 2018-11-08T10:17:39Z file_id: '5428' file_name: react_acs.pdf file_size: 920843 relation: main_file file_date_updated: 2018-11-08T10:17:39Z has_accepted_license: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2018/835 oa: '1' place: New York, NY, USA project: - _id: '1' name: SFB 901 - _id: '4' name: SFB 901 - Project Area C - _id: '13' name: SFB 901 - Subproject C1 - _id: '44' name: KogniHome - die mitdenkende Wohnung publication: Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES '18 publication_identifier: isbn: - 978-1-4503-6448-5 publication_status: accepted publisher: ACM quality_controlled: '1' related_material: link: - relation: software url: https://github.com/upbcuk status: public title: Fully-Featured Anonymous Credentials with Reputation System type: conference user_id: '25078' year: '2018' ... --- _id: '5820' abstract: - lang: eng text: "In this paper, we investigate the use of trusted execution environments (TEEs, such as Intel's SGX) for an anonymous communication infrastructure over untrusted networks.\r\nFor this, we present the general idea of exploiting trusted execution environments for the purpose of anonymous communication, including a continuous-time security framework that models strong anonymity guarantees in the presence of an adversary that observes all network traffic and can adaptively corrupt a constant fraction of participating nodes.\r\nIn our framework, a participating node can generate a number of unlinkable pseudonyms. Messages are sent from and to pseudonyms, allowing both senders and receivers of messages to remain anonymous. We introduce a concrete construction, which shows viability of our TEE-based approach to anonymous communication. The construction draws from techniques from cryptography and overlay networks. \r\nOur techniques are very general and can be used as a basis for future constructions with similar goals." author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Christian full_name: Scheideler, Christian id: '20792' last_name: Scheideler - first_name: Alexander full_name: Setzer, Alexander id: '11108' last_name: Setzer citation: ama: Blömer J, Bobolz J, Scheideler C, Setzer A. Provably Anonymous Communication Based on Trusted Execution Environments. apa: Blömer, J., Bobolz, J., Scheideler, C., & Setzer, A. (n.d.). Provably Anonymous Communication Based on Trusted Execution Environments. bibtex: '@book{Blömer_Bobolz_Scheideler_Setzer, title={Provably Anonymous Communication Based on Trusted Execution Environments}, author={Blömer, Johannes and Bobolz, Jan and Scheideler, Christian and Setzer, Alexander} }' chicago: Blömer, Johannes, Jan Bobolz, Christian Scheideler, and Alexander Setzer. Provably Anonymous Communication Based on Trusted Execution Environments, n.d. ieee: J. Blömer, J. Bobolz, C. Scheideler, and A. Setzer, Provably Anonymous Communication Based on Trusted Execution Environments. . mla: Blömer, Johannes, et al. Provably Anonymous Communication Based on Trusted Execution Environments. short: J. Blömer, J. Bobolz, C. Scheideler, A. Setzer, Provably Anonymous Communication Based on Trusted Execution Environments, n.d. date_created: 2018-11-25T08:08:40Z date_updated: 2022-01-06T07:02:43Z ddc: - '000' department: - _id: '7' - _id: '64' - _id: '79' file: - access_level: closed content_type: application/pdf creator: jbobolz date_created: 2018-12-31T09:55:30Z date_updated: 2018-12-31T09:55:30Z file_id: '6435' file_name: draft-2018.pdf file_size: 470968 relation: main_file success: 1 file_date_updated: 2018-12-31T09:55:30Z has_accepted_license: '1' language: - iso: eng project: - _id: '1' name: SFB 901 - _id: '4' name: SFB 901 - Project Area C - _id: '13' name: SFB 901 - Subproject C1 publication_status: draft status: public title: Provably Anonymous Communication Based on Trusted Execution Environments type: working_paper user_id: '27207' year: '2018' ... --- _id: '2379' abstract: - lang: eng text: 'In this paper, we introduce the notion of delegatable attribute-based anonymous credentials (DAAC). Such systems offer fine-grained anonymous access control and they give the credential holder the ability to issue more restricted credentials to other users. In our model, credentials are parameterized with attributes that (1) express what the credential holder himself has been certified and (2) define which attributes he may issue to others. Furthermore, we present a practical construction of DAAC. For this construction, we deviate from the usual approach of embedding a certificate chain in the credential. Instead, we introduce a novel approach for which we identify a new primitive we call dynamically malleable signatures (DMS) as the main ingredient. This primitive may be of independent interest. We also give a first instantiation of DMS with efficient protocols. ' author: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz citation: ama: 'Blömer J, Bobolz J. Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures. In: ACNS 2018 Applied Cryptography & Network Security. LNCS. doi:10.1007/978-3-319-93387-0_12' apa: Blömer, J., & Bobolz, J. (n.d.). Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures. ACNS 2018 Applied Cryptography & Network Security. The 16th International Conference on Applied Cryptography and Network Security, Leuven, Belgium. https://doi.org/10.1007/978-3-319-93387-0_12 bibtex: '@inproceedings{Blömer_Bobolz, series={LNCS}, title={Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures}, DOI={10.1007/978-3-319-93387-0_12}, booktitle={ACNS 2018 Applied Cryptography & Network security}, author={Blömer, Johannes and Bobolz, Jan}, collection={LNCS} }' chicago: Blömer, Johannes, and Jan Bobolz. “Delegatable Attribute-Based Anonymous Credentials from Dynamically Malleable Signatures.” In ACNS 2018 Applied Cryptography & Network Security. LNCS, n.d. https://doi.org/10.1007/978-3-319-93387-0_12. ieee: 'J. Blömer and J. Bobolz, “Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures,” presented at the The 16th International Conference on Applied Cryptography and Network Security, Leuven, Belgium, doi: 10.1007/978-3-319-93387-0_12.' mla: Blömer, Johannes, and Jan Bobolz. “Delegatable Attribute-Based Anonymous Credentials from Dynamically Malleable Signatures.” ACNS 2018 Applied Cryptography & Network Security, doi:10.1007/978-3-319-93387-0_12. short: 'J. Blömer, J. Bobolz, in: ACNS 2018 Applied Cryptography & Network Security, n.d.' conference: location: Leuven, Belgium name: The 16th International Conference on Applied Cryptography and Network Security date_created: 2018-04-17T12:28:25Z date_updated: 2023-01-10T10:28:43Z ddc: - '004' department: - _id: '7' - _id: '64' doi: 10.1007/978-3-319-93387-0_12 file: - access_level: closed content_type: application/pdf creator: ups date_created: 2018-11-02T13:41:16Z date_updated: 2018-11-02T13:41:16Z file_id: '5252' file_name: 2018-340.pdf file_size: 542171 relation: main_file success: 1 file_date_updated: 2018-11-02T13:41:16Z has_accepted_license: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://eprint.iacr.org/2018/340 oa: '1' project: - _id: '4' name: SFB 901 - Project Area C - _id: '1' name: SFB 901 - _id: '13' name: SFB 901 - Subproject C1 publication: ACNS 2018 Applied Cryptography & Network security publication_status: accepted series_title: LNCS status: public title: Delegatable Attribute-based Anonymous Credentials from Dynamically Malleable Signatures type: conference user_id: '25078' year: '2018' ... --- _id: '301' author: - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz citation: ama: Bobolz J. Efficient Verifier-Local Revocation for Anonymous Credentials. Universität Paderborn; 2015. apa: Bobolz, J. (2015). Efficient Verifier-Local Revocation for Anonymous Credentials. Universität Paderborn. bibtex: '@book{Bobolz_2015, title={Efficient Verifier-Local Revocation for Anonymous Credentials}, publisher={Universität Paderborn}, author={Bobolz, Jan}, year={2015} }' chicago: Bobolz, Jan. Efficient Verifier-Local Revocation for Anonymous Credentials. Universität Paderborn, 2015. ieee: J. Bobolz, Efficient Verifier-Local Revocation for Anonymous Credentials. Universität Paderborn, 2015. mla: Bobolz, Jan. Efficient Verifier-Local Revocation for Anonymous Credentials. Universität Paderborn, 2015. short: J. Bobolz, Efficient Verifier-Local Revocation for Anonymous Credentials, Universität Paderborn, 2015. date_created: 2017-10-17T12:41:50Z date_updated: 2022-01-06T06:58:51Z ddc: - '040' department: - _id: '64' file: - access_level: open_access content_type: application/pdf creator: florida date_created: 2018-03-20T07:47:11Z date_updated: 2018-07-20T09:54:22Z file_id: '1443' file_name: 301-thesis_jbobolz_final_02.pdf file_size: 1214027 relation: main_file file_date_updated: 2018-07-20T09:54:22Z has_accepted_license: '1' oa: '1' project: - _id: '1' name: SFB 901 - _id: '13' name: SFB 901 - Subprojekt C1 - _id: '4' name: SFB 901 - Project Area C publisher: Universität Paderborn status: public supervisor: - first_name: Johannes full_name: Blömer, Johannes id: '23' last_name: Blömer title: Efficient Verifier-Local Revocation for Anonymous Credentials type: mastersthesis urn: '3016' user_id: '27207' year: '2015' ... --- _id: '20832' author: - first_name: Wilhelm full_name: Schäfer, Wilhelm last_name: Schäfer - first_name: Stefan full_name: Dziwok, Stefan id: '3901' last_name: Dziwok orcid: http://orcid.org/0000-0002-8679-6673 - first_name: Uwe full_name: Pohlmann, Uwe last_name: Pohlmann - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz - first_name: Mike full_name: Czech, Mike last_name: Czech - first_name: Andreas Peter full_name: Dann, Andreas Peter id: '26886' last_name: Dann - first_name: Johannes full_name: Geismann, Johannes id: '20063' last_name: Geismann orcid: https://orcid.org/0000-0003-2015-2047 - first_name: Marcus full_name: Hüwe, Marcus id: '13606' last_name: Hüwe - first_name: Arthur full_name: Krieger, Arthur last_name: Krieger - first_name: Goran full_name: Piskachev, Goran id: '41936' last_name: Piskachev orcid: 0000-0003-4424-5838 - first_name: David full_name: Schubert, David id: '9106' last_name: Schubert - first_name: Rebekka full_name: Wohlrab, Rebekka last_name: Wohlrab citation: ama: Schäfer W, Dziwok S, Pohlmann U, et al. Seminar Theses of the Project Group Cybertron.; 2015. apa: Schäfer, W., Dziwok, S., Pohlmann, U., Bobolz, J., Czech, M., Dann, A. P., Geismann, J., Hüwe, M., Krieger, A., Piskachev, G., Schubert, D., & Wohlrab, R. (2015). Seminar Theses of the Project Group Cybertron. bibtex: '@book{Schäfer_Dziwok_Pohlmann_Bobolz_Czech_Dann_Geismann_Hüwe_Krieger_Piskachev_et al._2015, title={Seminar Theses of the Project Group Cybertron}, author={Schäfer, Wilhelm and Dziwok, Stefan and Pohlmann, Uwe and Bobolz, Jan and Czech, Mike and Dann, Andreas Peter and Geismann, Johannes and Hüwe, Marcus and Krieger, Arthur and Piskachev, Goran and et al.}, year={2015} }' chicago: Schäfer, Wilhelm, Stefan Dziwok, Uwe Pohlmann, Jan Bobolz, Mike Czech, Andreas Peter Dann, Johannes Geismann, et al. Seminar Theses of the Project Group Cybertron, 2015. ieee: W. Schäfer et al., Seminar Theses of the Project Group Cybertron. 2015. mla: Schäfer, Wilhelm, et al. Seminar Theses of the Project Group Cybertron. 2015. short: W. Schäfer, S. Dziwok, U. Pohlmann, J. Bobolz, M. Czech, A.P. Dann, J. Geismann, M. Hüwe, A. Krieger, G. Piskachev, D. Schubert, R. Wohlrab, Seminar Theses of the Project Group Cybertron, 2015. date_created: 2020-12-22T10:03:05Z date_updated: 2022-01-06T06:54:40Z department: - _id: '76' language: - iso: eng status: public title: Seminar Theses of the Project Group Cybertron type: report user_id: '5786' year: '2015' ... --- _id: '487' author: - first_name: Jan full_name: Bobolz, Jan id: '27207' last_name: Bobolz citation: ama: Bobolz J. Security Proofs for Pairing-Based Cryptography in the Generic Group Model. Universität Paderborn; 2013. apa: Bobolz, J. (2013). Security Proofs for Pairing-Based Cryptography in the Generic Group Model. Universität Paderborn. bibtex: '@book{Bobolz_2013, title={Security Proofs for Pairing-Based Cryptography in the Generic Group Model}, publisher={Universität Paderborn}, author={Bobolz, Jan}, year={2013} }' chicago: Bobolz, Jan. Security Proofs for Pairing-Based Cryptography in the Generic Group Model. Universität Paderborn, 2013. ieee: J. Bobolz, Security Proofs for Pairing-Based Cryptography in the Generic Group Model. Universität Paderborn, 2013. mla: Bobolz, Jan. Security Proofs for Pairing-Based Cryptography in the Generic Group Model. Universität Paderborn, 2013. short: J. Bobolz, Security Proofs for Pairing-Based Cryptography in the Generic Group Model, Universität Paderborn, 2013. date_created: 2017-10-17T12:42:27Z date_updated: 2022-01-06T07:01:28Z ddc: - '000' department: - _id: '64' file: - access_level: open_access content_type: application/pdf creator: jbobolz date_created: 2018-04-13T11:42:08Z date_updated: 2018-06-29T09:56:54Z file_id: '2346' file_name: thesis_jbobolz_final.pdf file_size: 874286 relation: main_file file_date_updated: 2018-06-29T09:56:54Z has_accepted_license: '1' oa: '1' project: - _id: '1' name: SFB 901 - _id: '4' name: SFB 901 - Project Area C - _id: '13' name: SFB 901 - Subproject C1 publisher: Universität Paderborn status: public title: Security Proofs for Pairing-Based Cryptography in the Generic Group Model type: bachelorsthesis urn: '4875' user_id: '27207' year: '2013' ...