---
_id: '29763'
abstract:
- lang: eng
  text: "Modern-day communication has become more and more digital. While this comes
    with many advantages such as a more efficient economy, it has also created more
    and more opportunities for various adversaries to manipulate communication or
    eavesdrop on it. The Snowden revelations in 2013 further highlighted the seriousness
    of these threats. To protect the communication of people, companies, and states
    from such threats, we require cryptography with strong security guarantees.\r\nDifferent
    applications may require different security properties from cryptographic schemes.
    For most applications, however, so-called adaptive security is considered a reasonable
    minimal requirement of security. Cryptographic schemes with adaptive security
    remain secure in the presence of an adversary that can corrupt communication partners
    to respond to messages of the adversaries choice, while the adversary may choose
    the messages based on previously observed interactions.\r\nWhile cryptography
    is associated the most with encryption, this is only one of many primitives that
    are essential for the security of digital interactions. This thesis presents novel
    identity-based encryption (IBE) schemes and verifiable random functions (VRFs)
    that achieve adaptive security as outlined above. Moreover, the cryptographic
    schemes presented in this thesis are proven secure in the standard model. That
    is without making use of idealized models like the random oracle model."
author:
- first_name: David
  full_name: Niehues, David
  id: '36113'
  last_name: Niehues
citation:
  ama: Niehues D. <i>More Efficient Techniques for Adaptively-Secure Cryptography</i>.;
    2022. doi:<a href="https://doi.org/10.25926/rdtq-jw45">10.25926/rdtq-jw45</a>
  apa: Niehues, D. (2022). <i>More Efficient Techniques for Adaptively-Secure Cryptography</i>.
    <a href="https://doi.org/10.25926/rdtq-jw45">https://doi.org/10.25926/rdtq-jw45</a>
  bibtex: '@book{Niehues_2022, title={More Efficient Techniques for Adaptively-Secure
    Cryptography}, DOI={<a href="https://doi.org/10.25926/rdtq-jw45">10.25926/rdtq-jw45</a>},
    author={Niehues, David}, year={2022} }'
  chicago: Niehues, David. <i>More Efficient Techniques for Adaptively-Secure Cryptography</i>,
    2022. <a href="https://doi.org/10.25926/rdtq-jw45">https://doi.org/10.25926/rdtq-jw45</a>.
  ieee: D. Niehues, <i>More Efficient Techniques for Adaptively-Secure Cryptography</i>.
    2022.
  mla: Niehues, David. <i>More Efficient Techniques for Adaptively-Secure Cryptography</i>.
    2022, doi:<a href="https://doi.org/10.25926/rdtq-jw45">10.25926/rdtq-jw45</a>.
  short: D. Niehues, More Efficient Techniques for Adaptively-Secure Cryptography,
    2022.
date_created: 2022-02-07T13:29:07Z
date_updated: 2022-02-07T13:32:28Z
ddc:
- '000'
department:
- _id: '558'
doi: 10.25926/rdtq-jw45
file:
- access_level: closed
  content_type: application/pdf
  creator: davnie
  date_created: 2022-02-07T13:26:05Z
  date_updated: 2022-02-07T13:26:05Z
  file_id: '29764'
  file_name: de2107.pdf
  file_size: 1542089
  relation: main_file
  success: 1
file_date_updated: 2022-02-07T13:26:05Z
has_accepted_license: '1'
keyword:
- public-key cryptography
- lattices
- pairings
- verifiable random functions
- identity-based encryption
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://elpub.bib.uni-wuppertal.de/servlets/DerivateServlet/Derivate-14686/de2107.pdf
oa: '1'
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_status: published
status: public
supervisor:
- first_name: Tibor
  full_name: Jager, Tibor
  id: '64669'
  last_name: Jager
- first_name: Anja
  full_name: Lehmann, Anja
  last_name: Lehmann
title: More Efficient Techniques for Adaptively-Secure Cryptography
type: dissertation
user_id: '36113'
year: '2022'
...
---
_id: '21396'
abstract:
- lang: eng
  text: "Verifiable random functions (VRFs) are essentially digital signatures with
    additional properties, namely verifiable uniqueness and pseudorandomness, which
    make VRFs a useful tool, e.g., to prevent enumeration in DNSSEC Authenticated
    Denial of Existence and the CONIKS key management system, or in the random committee
    selection of the Algorand blockchain.\r\n\r\nMost standard-model VRFs rely on
    admissible hash functions (AHFs) to achieve security against adaptive attacks
    in the standard model. Known AHF constructions are based on error-correcting codes,
    which yield asymptotically efficient constructions. However, previous works do
    not clarify how the code should be instantiated concretely in the real world.
    The rate and the minimal distance of the selected code have significant impact
    on the efficiency of the resulting cryptosystem, therefore it is unclear if and
    how the aforementioned constructions can be used in practice.\r\n\r\nFirst, we
    explain inherent limitations of code-based AHFs. Concretely, we assume that even
    if we were given codes that achieve the well-known Gilbert-Varshamov or McEliece-Rodemich-Rumsey-Welch
    bounds, existing AHF-based constructions of verifiable random functions (VRFs)
    can only be instantiated quite inefficiently. Then we introduce and construct
    computational AHFs (cAHFs). While classical AHFs are information-theoretic, and
    therefore work even in presence of computationally unbounded adversaries, cAHFs
    provide only security against computationally bounded adversaries. However, we
    show that cAHFs can be instantiated significantly more efficiently. Finally, we
    use our cAHF to construct the currently most efficient verifiable random function
    with full adaptive security in the standard model."
author:
- first_name: Tibor
  full_name: Jager, Tibor
  last_name: Jager
- first_name: David
  full_name: Niehues, David
  id: '36113'
  last_name: Niehues
citation:
  ama: 'Jager T, Niehues D. On the Real-World Instantiability of Admissible Hash Functions
    and Efficient Verifiable Random Functions. In: <i>Lecture Notes in Computer Science</i>.
    Cham; 2020. doi:<a href="https://doi.org/10.1007/978-3-030-38471-5_13">10.1007/978-3-030-38471-5_13</a>'
  apa: Jager, T., &#38; Niehues, D. (2020). On the Real-World Instantiability of Admissible
    Hash Functions and Efficient Verifiable Random Functions. In <i>Lecture Notes
    in Computer Science</i>. Cham. <a href="https://doi.org/10.1007/978-3-030-38471-5_13">https://doi.org/10.1007/978-3-030-38471-5_13</a>
  bibtex: '@inbook{Jager_Niehues_2020, place={Cham}, title={On the Real-World Instantiability
    of Admissible Hash Functions and Efficient Verifiable Random Functions}, DOI={<a
    href="https://doi.org/10.1007/978-3-030-38471-5_13">10.1007/978-3-030-38471-5_13</a>},
    booktitle={Lecture Notes in Computer Science}, author={Jager, Tibor and Niehues,
    David}, year={2020} }'
  chicago: Jager, Tibor, and David Niehues. “On the Real-World Instantiability of
    Admissible Hash Functions and Efficient Verifiable Random Functions.” In <i>Lecture
    Notes in Computer Science</i>. Cham, 2020. <a href="https://doi.org/10.1007/978-3-030-38471-5_13">https://doi.org/10.1007/978-3-030-38471-5_13</a>.
  ieee: T. Jager and D. Niehues, “On the Real-World Instantiability of Admissible
    Hash Functions and Efficient Verifiable Random Functions,” in <i>Lecture Notes
    in Computer Science</i>, Cham, 2020.
  mla: Jager, Tibor, and David Niehues. “On the Real-World Instantiability of Admissible
    Hash Functions and Efficient Verifiable Random Functions.” <i>Lecture Notes in
    Computer Science</i>, 2020, doi:<a href="https://doi.org/10.1007/978-3-030-38471-5_13">10.1007/978-3-030-38471-5_13</a>.
  short: 'T. Jager, D. Niehues, in: Lecture Notes in Computer Science, Cham, 2020.'
conference:
  end_date: 2019-08-16
  location: Waterloo, Canada
  name: Selected Areas in Cryptography
  start_date: 2019-08-12
date_created: 2021-03-08T16:50:31Z
date_updated: 2022-01-06T06:54:58Z
ddc:
- '000'
department:
- _id: '558'
doi: 10.1007/978-3-030-38471-5_13
file:
- access_level: closed
  content_type: application/pdf
  creator: davnie
  date_created: 2021-03-08T17:02:37Z
  date_updated: 2021-03-08T17:02:37Z
  file_id: '21399'
  file_name: Jager und Niehues - 2020 - On the Real-World Instantiability of Admissible
    Ha.pdf
  file_size: 706743
  relation: main_file
file_date_updated: 2021-03-08T17:02:37Z
has_accepted_license: '1'
keyword:
- Admissible hash functions
- Verifiable random functions
- Error-correcting codes
- Provable security
language:
- iso: eng
main_file_link:
- url: https://link.springer.com/content/pdf/10.1007%252F978-3-030-38471-5_13.pdf
place: Cham
project:
- _id: '1'
  name: SFB 901
- _id: '4'
  name: SFB 901 - Project Area C
- _id: '13'
  name: SFB 901 - Subproject C1
publication: Lecture Notes in Computer Science
publication_identifier:
  isbn:
  - '9783030384708'
  - '9783030384715'
  issn:
  - 0302-9743
  - 1611-3349
publication_status: published
quality_controlled: '1'
related_material:
  link:
  - relation: later_version
    url: https://eprint.iacr.org/2019/1335.pdf
status: public
title: On the Real-World Instantiability of Admissible Hash Functions and Efficient
  Verifiable Random Functions
type: book_chapter
user_id: '36113'
year: '2020'
...