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Symmetric Signcryption and E2EE Messaging in Keybase

Authors:
Joseph Jaeger , Georgia Institute of Technology
Akshaya Kumar , Georgia Institute of Technology
Igors Stepanovs , None
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DOI: 10.1007/978-3-031-58734-4_10 (login may be required)
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Presentation: Slides
Conference: EUROCRYPT 2024
Abstract: We introduce a new cryptographic primitive called symmetric signcryption, which differs from traditional signcryption because the sender and recipient share a secret key. We prove that a natural composition of symmetric encryption and signatures achieves strong notions of security against attackers that can learn and control many keys. We then identify that the core encryption algorithm of the Keybase encrypted messaging protocol can be modeled as a symmetric signcryption scheme. We prove the security of this algorithm, though our proof requires assuming non-standard, brittle security properties of the underlying primitives.
BibTeX
@inproceedings{eurocrypt-2024-33993,
  title={Symmetric Signcryption and E2EE Messaging in Keybase},
  publisher={Springer-Verlag},
  doi={10.1007/978-3-031-58734-4_10},
  author={Joseph Jaeger and Akshaya Kumar and Igors Stepanovs},
  year=2024
}