Cryptology ePrint Archive: Report 2013/456

On the Security of Group-based Proxy Re-encryption Scheme

Purushothama B R and B B Amberker

Abstract: Proxy re-encryption (PRE) allows a semi-trusted proxy to convert a ciphertext intended for Alice into a ciphertext for Bob without learning anything about the underlying plaintext. Chunbo Ma et al. have proposed a group based proxy re-encryption scheme to convert a ciphertext from one group to another. Any group member can independently decrypt the ciphertexts encrypted to its group. In their paper, the authors gave a security proof to say that the scheme is secure against adaptive chosen ciphertext attack. However, we highlight the flaws in their scheme and show that their scheme is not secure against adaptive chosen ciphertext attack. In this direction, we construct an adversary who issues only one decryption oracle query and break the security of their scheme with non-negligible advantage.

Category / Keywords: Public-key Cryptography, Proxy Re-encryption, Cryptanalysis

Date: received 23 Jul 2013, last revised 23 Jul 2013

Contact author: puru at nitgoa ac in

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Version: 20130727:010403 (All versions of this report)

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