Paper 2023/722

Composing Bridges

Mugurel Barcau, certSIGN , Bucharest, Romania, Institute of Mathematics “Simion Stoilow” of the Romanian Academy
Vicentiu Pasol, certSIGN , Bucharest, Romania, Institute of Mathematics “Simion Stoilow” of the Romanian Academy
George C Turcas, certSIGN , Bucharest, Romania, Babes-Bolyai University, Cluj-Napoca, Romania
Abstract

The present work builds on previous investigations of the authors (and their collaborators) regarding bridges, a certain type of morphisms between encryption schemes, making a step forward in developing a (category theory) language for studying relations between encryption schemes. Here we analyse the conditions under which bridges can be performed sequentially, formalizing the notion of composability. One of our results gives a sufficient condition for a pair of bridges to be composable. We illustrate that composing two bridges, each independently satisfying a previously established IND-CPA security definition, can actually lead to an insecure bridge. Our main result gives a sufficient condition that a pair of secure composable bridges should satisfy in order for their composition to be a secure bridge. We also introduce the concept of a complete bridge and show that it is connected to the notion of Fully composable Homomorphic Encryption (FcHE), recently considered by Micciancio. Moreover, we show that a result of Micciancio which gives a construction of FcHE schemes can be phrased in the language of complete bridges, where his insights can be formalised in a greater generality.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint.
Keywords
BridgeComposabilityFully Composable Homomorphic EncryptionIND-CPA security
Contact author(s)
mugurel barcau @ imar ro
vicentiu pasol @ imar ro
george turcas @ certsign ro
History
2023-05-22: approved
2023-05-19: received
See all versions
Short URL
https://ia.cr/2023/722
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2023/722,
      author = {Mugurel Barcau and Vicentiu Pasol and George C Turcas},
      title = {Composing Bridges},
      howpublished = {Cryptology ePrint Archive, Paper 2023/722},
      year = {2023},
      note = {\url{https://eprint.iacr.org/2023/722}},
      url = {https://eprint.iacr.org/2023/722}
}
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