International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Repairing a Security-Mediated Certificateless Encryption Scheme from PKC 2006

Joonsang Baek
Guilin Wang
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Abstract: At PKC 2006, Chow, Boyd, and Nieto introduced the concept of security-mediated certificateless (SMC) cryptography. This notion can be considered as a variant of certificateless cryptography with the property of instantaneous key revocation, or a variant of mediated cryptography without full key escrow. They presented a definition of security for SMC encryption, which covers (fully-adaptive) chosen ciphertext attack with public key replacement considered as a strong but essential attack on certificateless cryptographic schemes. They proposed two SMC encryption schemes, one is a generic construction based on any public key encryption, identity-based encryption and one-time signature schemes and the other is a concrete construction based on bilinear pairings, which were shown to be secure under their security definition. In this note, we, however, present two types of attacks demonstrating that their generic construction for SMC encryption fails to meet their security requirement. We then discuss how to repair the scheme and provide a provably-secure solution.
  title={Repairing a Security-Mediated Certificateless Encryption Scheme from PKC 2006},
  booktitle={IACR Eprint archive},
  keywords={public-key cryptography /},
  note={ 13272 received 26 Apr 2006, withdrawn 4 May 2006},
  author={Joonsang Baek and Guilin Wang},