International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Chosen-Ciphertext Secure Proxy Re-Encryption

Ran Canetti
Susan Hohenberger
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Abstract: In a proxy re-encryption (PRE) scheme, a proxy is given special information that allows it to translate a ciphertext under one key into a ciphertext of the same message under a different key. The proxy cannot, however, learn anything about the messages encrypted under either key. PRE schemes have many practical applications, including distributed storage, email, and DRM. Previously proposed re-encryption schemes achieved only semantic security; in contrast, applications often require security against chosen ciphertext attacks. We propose a definition of security against chosen ciphertext attacks for PRE schemes, and present a scheme that satisfies the definition. Our construction is efficient and based only on the Decisional Bilinear Diffie-Hellman assumption in the standard model. We also formally capture CCA security for PRE schemes via both a game-based definition and simulation-based definitions that guarantee universally composable security. We note that, simultaneously with our work, Green and Ateniese proposed a CCA-secure PRE, discussed herein.
  title={Chosen-Ciphertext Secure Proxy Re-Encryption},
  booktitle={IACR Eprint archive},
  keywords={public-key cryptography / re-encryption, chosen-ciphertext security, obfuscation},
  note={Full version of paper in ACM CCS 2007. 13815 received 8 May 2007, last revised 29 Oct 2007},
  author={Ran Canetti and Susan Hohenberger},