International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 27 September 2015

Jayaprakash Kar
ePrint Report ePrint Report
Recently, Choi et al. proposed certificateless short signature scheme in random oracle model and the author claims that it is provably secure. Certificateless Public Key Cryptography is a new paradigm, where it allows resolving the inherent key escrow and key management problem. Attack to certificateless signature scheme are of two types as Type-I where the adversary can replace the public key of the user and cannot able to retrieve the master secret key from Key Generator Center (KGC). In Type-II, the adversary can able to obtain the master secret key and cannot replace the public key of the user. In this paper we have proven that, the proposed scheme is not secure against Type-I adversary. To prove, we solve linear Diophantine equation

and obtain the partial-private key of the user.

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