International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Cryptanalysis of Libert-Vergnaud Proxy Re-encryption Scheme

Zhengjun Cao
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Abstract: In 2008, Libert and Vergnaud put forth a proxy re-encryption scheme (LV08 for short). Unlike some earlier PRE schemes, the LV08 scheme specifies a validity-checking process to guarantee that the received ciphertext is well-formed. In this paper, we clarify an ultimate fact that the received message is well-formed is the premise to decryption in all encryption schemes. The underlying mechanism to keep the communicated message well-formed in encryption schemes is another topic. The authors ignored the fact and proposed a cumbersome presentation. We will simplify the LV08 scheme and show its security level is the same as that of the scheme proposed by Ateniese et al in 2005. Therefore, the LV08 scheme can not ensure chosen-ciphertext security as claimed.
  title={Cryptanalysis of  Libert-Vergnaud Proxy Re-encryption Scheme},
  booktitle={IACR Eprint archive},
  keywords={cryptographic protocols /},
  note={ 14769 received 5 Jun 2010, last revised 9 Jun 2010, withdrawn 9 Jun 2010},
  author={Zhengjun Cao},