---
_id: '63403'
abstract:
- lang: eng
  text: "Stateful signatures like the NIST standardized signature schemes LMS and
    XMSS provide an efficient and mature realization of post-quantum secure signature
    schemes. They are recommended for long-term use cases like e.g. firmware signing.
    However, stateful signature schemes require to properly manage a so-called state.
    In stateful signature schemes like LMS and XMSS, signing keys consist of a set
    of keys of a one-time signature scheme and it has to be guaranteed that each one-time
    key is used only once. This is done by updating a state in each signature computation,
    basically recording which one-time keys have already been used. While this is
    straightforward in centralized systems, in distributed systems like secure enclaves
    consisting of e.g. multiple hardware security modules (HSMs) with limited communication
    keeping a distributed state that at any point in time is consistent among all
    parties involved presents a challenge. This challenge is not addressed by the
    current standardization processes. \r\nIn this paper we present a security model
    for the distributed key management of post-quantum secure stateful signatures
    like XMSS and LMS. We also present a simple, efficient, and easy to implement
    protocol proven secure in this security model, i.e. the protocol guarantees at
    any point in time a consistent state among the parties in a distributed system,
    like a distributed security enclave. The security model is defined in the universal
    composabilty (UC) framework by Ran Canetti by providing an ideal functionality
    for the distributed key management for stateful signatures. Hence our protocol
    remains secure even if arbitrarily composed with other instances of the same or
    other protocols, a necessity for the security of distributed key management protocols.
    Our main application are security enclaves consisting of HSMs, but the model and
    the protocol can easily be adapted to other scenarios of distributed key management
    of stateful signature schemes."
author:
- first_name: Johannes
  full_name: Blömer, Johannes
  id: '23'
  last_name: Blömer
- first_name: Henrik
  full_name: Bröcher, Henrik
  id: '41047'
  last_name: Bröcher
  orcid: 0009-0008-3938-5485
- first_name: Volker
  full_name: Krummel, Volker
  last_name: Krummel
- first_name: Laurens Alexander
  full_name: Porzenheim, Laurens Alexander
  id: '47434'
  last_name: Porzenheim
citation:
  ama: Blömer J, Bröcher H, Krummel V, Porzenheim LA. Secure Distributed State Management
    for Stateful Signatures with a Practical and Universally Composable Protocol.
  apa: Blömer, J., Bröcher, H., Krummel, V., &#38; Porzenheim, L. A. (n.d.). <i>Secure
    Distributed State Management for Stateful Signatures with a Practical and Universally
    Composable Protocol</i>.
  bibtex: '@article{Blömer_Bröcher_Krummel_Porzenheim, title={Secure Distributed State
    Management for Stateful Signatures with a Practical and Universally Composable
    Protocol}, author={Blömer, Johannes and Bröcher, Henrik and Krummel, Volker and
    Porzenheim, Laurens Alexander} }'
  chicago: Blömer, Johannes, Henrik Bröcher, Volker Krummel, and Laurens Alexander
    Porzenheim. “Secure Distributed State Management for Stateful Signatures with
    a Practical and Universally Composable Protocol,” n.d.
  ieee: J. Blömer, H. Bröcher, V. Krummel, and L. A. Porzenheim, “Secure Distributed
    State Management for Stateful Signatures with a Practical and Universally Composable
    Protocol.” .
  mla: Blömer, Johannes, et al. <i>Secure Distributed State Management for Stateful
    Signatures with a Practical and Universally Composable Protocol</i>.
  short: J. Blömer, H. Bröcher, V. Krummel, L.A. Porzenheim, (n.d.).
date_created: 2025-12-22T21:23:22Z
date_updated: 2025-12-23T11:30:38Z
department:
- _id: '34'
- _id: '64'
keyword:
- distributed state
- hash-based signature
- stateful hash-based signature
- universal composability
- secure enclave
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://eprint.iacr.org/2025/2278.pdf
oa: '1'
page: '22'
project:
- _id: '191'
  name: 'PhoQuant: Photonische Quantencomputer -  Quantencomputing Testplattform'
publication_status: submitted
status: public
title: Secure Distributed State Management for Stateful Signatures with a Practical
  and Universally Composable Protocol
type: preprint
user_id: '41047'
year: '2025'
...
---
_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., &#38; Bröcher, H. (2023). <i>On the impossibility of
    surviving (iterated) deletion of weakly dominated strategies in rational MPC</i>.
    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. <i>On the Impossibility of Surviving (Iterated) Deletion
    of Weakly Dominated Strategies in Rational MPC</i>. 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: '13128'
author:
- first_name: Henrik
  full_name: Bröcher, Henrik
  id: '41047'
  last_name: Bröcher
citation:
  ama: Bröcher H. <i>Rational Secure Multiparty Computation</i>. Universität Paderborn;
    2019.
  apa: Bröcher, H. (2019). <i>Rational Secure Multiparty Computation</i>. Universität
    Paderborn.
  bibtex: '@book{Bröcher_2019, title={Rational Secure Multiparty Computation}, publisher={Universität
    Paderborn}, author={Bröcher, Henrik}, year={2019} }'
  chicago: Bröcher, Henrik. <i>Rational Secure Multiparty Computation</i>. Universität
    Paderborn, 2019.
  ieee: H. Bröcher, <i>Rational Secure Multiparty Computation</i>. Universität Paderborn,
    2019.
  mla: Bröcher, Henrik. <i>Rational Secure Multiparty Computation</i>. Universität
    Paderborn, 2019.
  short: H. Bröcher, Rational Secure Multiparty Computation, Universität Paderborn,
    2019.
date_created: 2019-09-04T08:04:12Z
date_updated: 2022-01-06T06:51:28Z
ddc:
- '000'
department:
- _id: '64'
extern: '1'
file:
- access_level: open_access
  content_type: application/pdf
  creator: bhenrik
  date_created: 2019-09-04T07:59:31Z
  date_updated: 2020-10-30T15:59:34Z
  file_id: '13129'
  file_name: thesis_broecher.pdf
  file_size: 746819
  relation: main_file
file_date_updated: 2020-10-30T15:59:34Z
has_accepted_license: '1'
language:
- iso: eng
oa: '1'
project:
- _id: '13'
  name: SFB 901 - Subproject C1
- _id: '1'
  name: SFB 901
- _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: Rational Secure Multiparty Computation
type: mastersthesis
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: <i>Proceedings of the 13th International Conference
    on Availability, Reliability and Security - ARES ’18</i>. New York, NY, USA: ACM.
    doi:<a href="https://doi.org/10.1145/3230833.3234517">10.1145/3230833.3234517</a>'
  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 <i>Proceedings of the 13th International Conference on Availability,
    Reliability and Security - ARES ’18</i>. New York, NY, USA: ACM. <a href="https://doi.org/10.1145/3230833.3234517">https://doi.org/10.1145/3230833.3234517</a>'
  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={<a href="https://doi.org/10.1145/3230833.3234517">10.1145/3230833.3234517</a>},
    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 <i>Proceedings of the 13th International Conference
    on Availability, Reliability and Security - ARES ’18</i>. New York, NY, USA: ACM,
    n.d. <a href="https://doi.org/10.1145/3230833.3234517">https://doi.org/10.1145/3230833.3234517</a>.'
  ieee: K. Bemmann <i>et al.</i>, “Fully-Featured Anonymous Credentials with Reputation
    System,” in <i>Proceedings of the 13th International Conference on Availability,
    Reliability and Security - ARES ’18</i>, Hamburg, Germany.
  mla: Bemmann, Kai, et al. “Fully-Featured Anonymous Credentials with Reputation
    System.” <i>Proceedings of the 13th International Conference on Availability,
    Reliability and Security - ARES ’18</i>, ACM, doi:<a href="https://doi.org/10.1145/3230833.3234517">10.1145/3230833.3234517</a>.
  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'
...