Identity-based encryption with (almost) tight security in the multi-instance, multi-ciphertext setting

Dennis Hofheinz; Jessica Koch; Christoph Striecks

Paper 2015/123

Identity-based encryption with (almost) tight security in the multi-instance, multi-ciphertext setting

Dennis Hofheinz, Jessica Koch, and Christoph Striecks

Abstract

We construct an identity-based encryption (IBE) scheme that is tightly secure in a very strong sense. Specifically, we consider a setting with many instances of the scheme and many encryptions per instance. In this setting, we reduce the security of our scheme to a variant of a simple assumption used for a similar purpose by Chen and Wee (Crypto 2013). The security loss of our reduction is O(k) (where k is the security parameter). Our scheme is the first IBE scheme to achieve this strong flavor of tightness under a simple assumption. Technically, our scheme is a variation of the IBE scheme by Chen and Wee. However, in order to “lift” their results to the multi-instance, multi-ciphertext case, we need to develop new ideas. In particular, while we build on (and extend) their high-level proof strategy, we deviate significantly in the low-level proof steps.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: A minor revision of an IACR publication in PKC 2015
Keywords: identity-based encryption tight security bilinear maps
Contact author(s): Christoph Striecks @ kit edu
History: 2015-02-26: received
Short URL: https://ia.cr/2015/123
License: CC BY

BibTeX

@misc{cryptoeprint:2015/123,
      author = {Dennis Hofheinz and Jessica Koch and Christoph Striecks},
      title = {Identity-based encryption with (almost) tight security in the multi-instance, multi-ciphertext setting},
      howpublished = {Cryptology {ePrint} Archive, Paper 2015/123},
      year = {2015},
      url = {https://eprint.iacr.org/2015/123}
}