Bull. Korean Math. Soc. 2016; 53(4): 1051-1069
Printed July 31, 2016
https://doi.org/10.4134/BKMS.b150516
Copyright © The Korean Mathematical Society.
Manoj Kumar Chande and Cheng-Chi Lee
Shri Shankaracharya Institute of Professional Management \& Technology, Asia University
Combining the concept of self-certified public key and message recovery, Li-Zhang-Zhu (LZZ) gives the proxy signature scheme with message recovery using self-certified public key. The security of the proposed scheme is based on the discrete logarithm problem (DLP) and one-way hash function (OWHF). Their scheme accomplishes the tasks of public key verification, proxy signature verification, and message recovery in a logically single step. In addition, their scheme satisfies all properties of strong proxy signature and does not use secure channel in the communication between the original signer and the proxy signer. In this paper, it is shown that in their signature scheme a malicious signer can cheat the system authority (SA), by obtaining a proxy signature key without the permission of the original signer. At the same time malicious original signer can also cheat the SA, he can also obtain a proxy signature key without the permission of the proxy signer. An improved signature scheme is being proposed, which involves the remedial measures to get rid of security flaws of the LZZ et al.'s. The security and performance analysis shows that the proposed signature scheme is maintaining higher level of security, with little bit of computational complexity.
Keywords: discrete logarithm, digital signature, proxy signature, message recovery
MSC numbers: 94A60
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