Weaknesses and improvements of an efficient certificateless signature scheme without using bilinear pairings

Abstract

SUMMARY The certificateless signature (CLS) scheme is a special signature scheme that solves the key escrow problem in identity‐based signature schemes. In CLS schemes, the private key is generated cooperatively by the key generator center (KGC) and signer, such that a malicious KGC cannot masquerade as the signer and sign a message. He et al . in 2011 proposed an efficient CLS scheme without using bilinear pairings. However, we discovered that the CLS scheme by He et al . cannot resist a strong type 2 adversary if this adversary replaces the master public key of the KGC. This work proposes an improved scheme that overcomes this weakness. Copyright © 2012 John Wiley & Sons, Ltd.