An Improved Certificateless Aggregate Signature

Abstract

Recently, Hou et al. proposed an improved certificateless aggregate signature (CLAS) scheme based on Xiong et al's scheme. They also demonstrated the scheme is provably secure in the random oracle model. Unfortunately, by giving concrete attacks, we point out that Hou et al.'s scheme is not secure in their security model. Then, we propose an improved certificateless signature (CLS) scheme and use it to construct an improved certificateless aggregate signature (CLAS) scheme.

Cryptanalysis and Further Improvement of a Certificateless Aggregate Signature Scheme

“…Recently, Deng et al [4] proposed an efficient improvedCLAS scheme of Hou et al [10] CLAS scheme. In this paper, we first give a detail review of Deng et al CLS and CLAS scheme then show that proposed CLAS is insecure against concrete attacks.…”

“…We point out that the security leaks of the scheme that is depends on the user secret key i ID usk and a random number i r select by the user but malicious KGC computes the fixed value pub i P r , K x i and forge the signature without the help of i ID usk and i r . We proposed a certificateless signature scheme to remove the security leaks arise in Deng et al [4].…”

“…Cheng et al [9] also proves that Xiong et al [8] scheme is also insecure against honest but curious and malicious but passive attack. Deng et al [4] proves that Hou et al [10] scheme is insecure against malicious but passive attack and gives an improvement CLAS scheme and show that this scheme is secure against malicious but passive attack. In this paper we prove that Deng et al [4] is insecure against the honest but curious attack by type II adversary while it is secure against malicious but passive attack.…”