Paper 2015/457

Generic Conversions from CPA to CCA secure Functional Encryption

Mridul Nandi and Tapas Pandit

Abstract

In 2004, Canetti-Halevi-Katz and later Boneh-Katz showed generic CCA-secure PKE constructions from a CPA-secure IBE. Goyal et al. in 2006 further extended the aforementioned idea implicitly to provide a specific CCA-secure KP-ABE with policies represented by monotone access trees. Later, Yamada et al. in 2011 generalized the CPA to CCA conversion to all those ABE, where the policies are represented by either monotone access trees (MAT) or monotone span programs (MSP), but not the others like sets of minimal sets. Moreover, the underlying CPA-secure constructions must satisfy one of the two features called key-delegation and verifiability. Along with ABE, many other different encryptions schemes, such as inner-product, hidden vector, spatial encryption schemes etc. can be studied under an unified framework, called functional encryption (FE), as introduced by Boneh-Sahai-Waters in 2011. The generic conversions, due to Yamada et al., can not be applied to all these functional encryption schemes. On the other hand, to the best of our knowledge, there is no known CCA-secure construction beyond ABE over MSP and MAT. This paper provides different ways of obtaining CCA-secure functional encryptions of almost all categories. In particular, we provide a generic conversion from a CPA-secure functional encryption into a CCA-secure functional encryption provided the underlying CPA-secure encryption scheme has either restricted delegation or verifiability feature. We observe that almost all functional encryption schemes have this feature. The KP-FE schemes of Waters (proposed in 2012) and Attrapadung (proposed in 2014) for regular languages do not possess the usual delegation property. However, they can be converted into corresponding CCA-secure schemes as they satisfy the restricted delegation.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint. MINOR revision.
Keywords
Functional encryptionPredicate encryptionDelegationVerifiabilityGeneric Conversion
Contact author(s)
tapasgmmath @ gmail com
History
2015-06-05: last of 3 revisions
2015-05-14: received
See all versions
Short URL
https://ia.cr/2015/457
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2015/457,
      author = {Mridul Nandi and Tapas Pandit},
      title = {Generic Conversions from CPA to CCA secure Functional Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2015/457},
      year = {2015},
      note = {\url{https://eprint.iacr.org/2015/457}},
      url = {https://eprint.iacr.org/2015/457}
}
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