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Mathematical Problems in Engineering
Volume 2014, Article ID 761487, 5 pages
Research Article

On Delegatability of Some Strong Designated Verifier Signature Schemes

School of Computer Science and Software, Tianjin Polytechnic University, No. 399, Binshuixi Road, Tianjin 300387, China

Received 25 December 2013; Revised 27 February 2014; Accepted 7 March 2014; Published 1 April 2014

Academic Editor: Kwok-Wo Wong

Copyright © 2014 Baoyuan Kang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A strong designated verifier signature scheme makes it possible for a signer to convince a designated verifier that she has signed a message in such a way that the designated verifier cannot transfer the signature to a third party, and no third party can even verify the validity of a designated verifier signature. In 2005, Lipmaa, Wang, and Bao identified a new essential security property, non delegatability, of designated verifier signature schemes. Briefly, in a non delegatability designated verifier signature scheme, neither a signer nor a designated verifier can delegate the signing rights to any third party without revealing their secret keys. However, this paper shows that four recently proposed strong designated verifier signature schemes are delegatable. These schemes do not satisfy non delegatability secure requirement of strong designated verifier signature schemes.