Proxy Re-Encryption Schemes with Key Privacy from LWE

Le Trieu Phong; Lihua Wang; Yoshinori Aono; Manh Ha Nguyen; Xavier Boyen

Paper 2016/327

Proxy Re-Encryption Schemes with Key Privacy from LWE

Le Trieu Phong, Lihua Wang, Yoshinori Aono, Manh Ha Nguyen, and Xavier Boyen

Abstract

Proxy re-encryption (PRE) is a cryptographic primitive in which a proxy can transform Alice's ciphertexts into ones decryptable by Bob. Key-private PRE specifies an additional level of security, requiring that proxy keys leak no information on the identities of Alice and Bob. In this paper, we build two key-private PRE schemes: (1) we propose a CPA-secure key-private PRE scheme in the standard model, and (2) we then transform it into a CCA-secure scheme in the random oracle model. Both schemes enjoy following properties: both are uni-directional and the CPA-secure one is a multi-hop scheme. In addition, the security of our schemes is based on the hardness of the standard Learning-With-Errors (LWE) problem, itself reducible from worst-case lattice hard problems that are conjectured immune to quantum cryptanalysis, or ``post-quantum''. We implement the CPA-secure scheme and point out that, among many applications, it can be sufficiently used for the practical task of key rotation over encrypted data.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Published elsewhere. Major revision. INDOCRYPT 2013
Contact author(s): phong @ nict go jp
History: 2017-07-26: revised; 2016-03-25: received; See all versions
Short URL: https://ia.cr/2016/327
License: CC BY

BibTeX

@misc{cryptoeprint:2016/327,
      author = {Le Trieu Phong and Lihua Wang and Yoshinori Aono and Manh Ha Nguyen and Xavier Boyen},
      title = {Proxy Re-Encryption Schemes with Key Privacy from {LWE}},
      howpublished = {Cryptology {ePrint} Archive, Paper 2016/327},
      year = {2016},
      url = {https://eprint.iacr.org/2016/327}
}