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


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.

Available format(s)
Public-key cryptography
Publication info
Published elsewhere. Major revision. INDOCRYPT 2013
Contact author(s)
phong @ nict go jp
2017-07-26: revised
2016-03-25: received
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Creative Commons Attribution


      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},
      note = {\url{}},
      url = {}
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