Keyword: Threshold Signatures

@Article{2026-caiseextension-bakhtina,
  title = {Securing Organisational Digital Identity: A Full-Lifecycle Approach to Distributed Key Management},
  author = {Mariia Bakhtina and Jan Kvapil and Petr Svenda and Raimundas Matulevicius},
  journal = {International Journal of Information Security},
  volume = {25},
  pages = {131},
  year = {2026},
  doi = {10.1007/s10207-026-01291-5},
  number = {4},
  issn = {1615-5270},
  keywords = {distributed control, key management, organisational digital identity, security, threshold signatures, zero trust},
  abstract = {Organisational Digital Identity (ODI) commonly relies on keys controlled by a single entity, creating a single point of failure and preventing organisations from cryptographically enforcing custom access policies. Migrating to fully decentralised identity infrastructures is costly and time-consuming, especially in regulated e-governance systems. This paper addresses these limitations through an Information Systems Engineering contribution: the design and experimental validation of a Distributed Key Management System (DKMS) that secures a centrally managed, PKI-based ODI without replacing the existing infrastructure. Rather than introducing new cryptographic primitives, the DKMS selects and composes existing threshold signature schemes to cover the complete key management lifecycle, from generation and operational usage through to post-operational archiving, recovery, and destruction. Partial custody through threshold signatures distributes control over an organisation's signing key among multiple semi-trusted representatives, while remaining fully backwards compatible with standard RSA and ECDSA verification. A semi-automated signer mechanism is introduced to enforce human-in-the-loop policies without prohibitive latency. The design is validated through a proof-of-concept implementation for the X-Road data exchange system, evaluated across RSA and ECDSA threshold groups of sizes 2-of-2, 3-of-5, and 11-of-15. Results show that RSA-based DKMS achieves round-trip times comparable to single-party hardware tokens, confirming DKMS-based signing as a practical, zero-trust alternative to single-controller identity management.},
}

@InProceedings{2024-caise-bakhtina,
  title = {The Power of Many: Securing Organisational Identity Through Distributed Key Management},
  author = {Mariia Bakhtina and Jan Kvapil and Petr Svenda and Raimundas Matulevicius},
  booktitle = {Advanced Information Systems Engineering},
  pages = {475--491},
  publisher = {Springer Nature Switzerland},
  location = {Cham},
  isbn = {978-3-031-61057-8},
  doi = {10.1007/978-3-031-61057-8_28},
  keywords = {distributed control, key management, organisational digital identity, security, threshold signatures, zero trust},
  shorttitle = {The Power of Many},
  abstract = {Organisational Digital Identity ({ODI}) often relies on the credentials and keys being controlled by a single person-representative. Moreover, some Information Systems ({IS}) outsource the key management to a third-party controller. Both the centralisation and outsourcing of the keys threaten data integrity within the {IS}, allegedly provided by a trusted organisation. Also, outsourcing the control prevents an organisation from cryptographically enforcing custom policies, e.g. time-based, regarding the data originating from it. To address this, we propose a Distributed Key Management System ({DKMS}) that eliminates the risks associated with centralised control over an organisation’s identity and allows organisation-enforceable policies. The {DKMS} employs threshold signatures to directly involve multiple organisation’s representatives (e.g. employees, {IS} components, and external custodians) in data signing on its behalf. The threshold signature creation and,
therefore, the custom signing policy inclusion, is fully backwards compatible with commonly used signing schemes, such as {RSA} or {ECDSA}. The feasibility of the proposed system is shown in an example data exchange system, X-Road. The implementation confirms the ability of the design to achieve distributed control over the {ODI} during the operational key phase. Excluding a network delay, the implementation introduces less than 200 ms overhead compared to the built-in signing solution.},
  editor = {Guizzardi, Giancarlo and Santoro, Flavia and Mouratidis, Haralambos and Soffer, Pnina},
  date = {2024},
  langid = {english},
}