Paper 2024/1938

SoK: On the Security Goals of Key Transparency Systems

Nicholas Brandt, ETH Zurich
Mia Filić, ETH Zurich
Sam A. Markelon, University of Florida
Abstract

Key Transparency (KT) systems have emerged as a critical technology for adding verifiability to the distribution of public keys used in end-to-end encrypted messaging services. Despite substantial academic interest, increased industry adoption, and IETF standardization efforts, KT systems lack a holistic and formalized security model, limiting their resilience to practical threats and constraining future development. In this paper, we survey the existing KT literature and present the first cryptographically sound formalization of KT as an ideal functionality. Our work clarifies the underlying assumptions, defines core security properties, and highlights potential vulnerabilities in deployed KT systems. We prove in the Universal Composability framework that our concrete protocol achieves KT security as defined by our formalism. Our KT protocol builds on the latest trends in KT design, guided by the formalization.

Note: Typo.

Metadata
Available format(s)
PDF
Category
Applications
Publication info
Preprint.
Keywords
Key TransparencyPKI
Contact author(s)
crypto @ nicholasbrandt de
filicmia @ gmail com
smarkelon @ ufl edu
History
2025-04-24: last of 2 revisions
2024-11-29: received
See all versions
Short URL
https://ia.cr/2024/1938
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/1938,
      author = {Nicholas Brandt and Mia Filić and Sam A. Markelon},
      title = {{SoK}: On the Security Goals of Key Transparency Systems},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1938},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1938}
}
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