A secure extension of the Kwak-Moon group signcryption scheme
This paper presents the secure extension of the Kwak-Moon group signcryption scheme [Kwak D, Moon S. Efficient distributed signcryption scheme as group signcryption. In: First applied cryptography and network security - ACNS'03. Lecturer notes in computer science, vol. 2846. Springer-Verlag; 2003. p. 403-17] as a countermeasure against the cryptanalysis in [Wang G, Deng RH, Kwak D, Moon S. Security analysis of two signcryption scheme. In: Information security conference - ISC 2004. Lecturer notes in computer science, vol. 3225. Springer-Verlag; 2004. p. 123-33]. The cryptanalysis revealed that the Kwak-Moon scheme cannot satisfy the properties of unforgeability, coalition-resistance, and traceability. Therefore, to avoid these weaknesses, while providing the same functions, we add confidentiality to the original group signature by distributing a shared secret among group members through an efficient group key agreement. However, in case of just combining a group signature and a group key agreement, if an attacker who does not belong to the group acquires a valid group signature, it is still possible for him to impersonate a valid group member and delegate the group. Thus, to avoid this possibility, the proposed scheme confirms whether or not the sender is equal to the signer by including a session key encryption in the signed message. In addition, we analyze the security of the proposed scheme and apply it to an anonymous statistical survey of attributes. (C) 2006 Elsevier Ltd. All rights reserved.
signcryption group signature signature key agreement public-key cryptography