Paper 2014/933

Certificateless Proxy Re-Encryption Without Pairing: Revisited

Akshayaram Srinivasan and C. Pandu Rangan


Proxy Re-Encryption was introduced by Blaze, Bleumer and Strauss to efficiently solve the problem of delegation of decryption rights. In proxy re-encryption, a semi-honest proxy transforms a ciphertext intended for Alice to a ciphertext of the same message for Bob without learning anything about the underlying message. From its introduction, several proxy re-encryption schemes in the Public Key Infrastructure (PKI) and Identity (ID) based setting have been proposed. In practice, systems in the public key infrastructure suffer from the \textit{certificate management problem} and those in identity based setting suffer from the \textit{key escrow problem}. Certificateless Proxy Re-encryption schemes enjoy the advantages provided by ID-based constructions without suffering from the key escrow problem. In this work, we construct the \textit{first} unidirectional, single-hop CCA-secure certificateless proxy re-encryption scheme \textit{without} \textit{pairing} by extending the PKI based construction of Chow et al. proposed in 2010. We prove its security in the random oracle model under the Computational Diffie-Hellman (CDH) assumption. Prior to this work, the only secure certificateless proxy re-encryption scheme is due to Guo et al. proposed in 2013 using bilinear pairing. They proved their construction is RCCA-secure under $q$-weak Decisional Bilinear Diffie-Hellman assumption. The construction proposed in this work is more efficient than that system and its security relies on more standard assumptions. We also show that the recently proposed construction of Yang et al. is insecure with respect to the security model considered in this work.

Available format(s)
Public-key cryptography
Publication info
Published elsewhere. Minor revision. ACM Asia-CCS SCC 2015
Certificateless Proxy Re-EncryptionRandom OracleComputational Diffie-Hellman
Contact author(s)
akshayram1993 @ gmail com
2015-02-10: last of 3 revisions
2014-11-14: received
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      author = {Akshayaram Srinivasan and C.  Pandu Rangan},
      title = {Certificateless Proxy Re-Encryption Without Pairing: Revisited},
      howpublished = {Cryptology ePrint Archive, Paper 2014/933},
      year = {2014},
      note = {\url{}},
      url = {}
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