Paper 2015/566

A Framework for Identity-Based Encryption with Almost Tight Security

Nuttapong Attrapadung, Goichiro Hanaoka, and Shota Yamada

Abstract

We show a framework for constructing identity-based encryption (IBE) schemes that are (almost) tightly secure in the multi-challenge and multi-instance setting. In particular, we formalize a new notion called broadcast encoding, analogously to encoding notions by Attrapadung (Eurocrypt '14) and Wee (TCC '14). We then show that it can be converted into such an IBE. By instantiating the framework using several encoding schemes (new or known ones), we obtain the following: - We obtain (almost) tightly secure IBE in the multi-challenge, multi-instance setting, both in composite and prime-order groups. The latter resolves the open problem posed by Hofheinz et al (PKC '15). - We obtain the first (almost) tightly secure IBE with sub-linear size public parameters (master public keys). In particular, we can set the size of the public parameters to constant at the cost of longer ciphertexts. This gives a partial solution to the open problem posed by Chen and Wee (Crypto '13). By applying (a variant of) the Canetti-Halevi-Katz transformation to our schemes, we obtain several CCA-secure PKE schemes with tight security in the multi-challenge, multi-instance setting. One of our schemes achieves very small ciphertext overhead, consisting of less than 12 group elements. This significantly improves the state-of-the-art construction by Libert et al.~(in ePrint Archive) which requires 47 group elements. Furthermore, by modifying one of our IBE schemes obtained above, we can make it anonymous. This gives the first anonymous IBE whose security is almost tightly shown in the multi-challenge setting.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint. MINOR revision.
Contact author(s)
yamada-shota @ aist go jp
History
2015-06-17: received
Short URL
https://ia.cr/2015/566
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2015/566,
      author = {Nuttapong Attrapadung and Goichiro Hanaoka and Shota Yamada},
      title = {A Framework for Identity-Based Encryption with  Almost Tight Security},
      howpublished = {Cryptology ePrint Archive, Paper 2015/566},
      year = {2015},
      note = {\url{https://eprint.iacr.org/2015/566}},
      url = {https://eprint.iacr.org/2015/566}
}
Note: In order to protect the privacy of readers, eprint.iacr.org does not use cookies or embedded third party content.