The signcryption is a relatively new cryptographic technique that is supposedto fulfill the functionalities of encryption and digital signature in a singlelogical step. Several signcryption schemes are proposed throughout the years,each of them having its own problems and limitations. In this paper, thesecurity of a recent signcryption scheme, i.e. Hwang et al.'s scheme isanalyzed, and it is proved that it involves several security flaws andshortcomings. Several devastating attacks are also introduced to the mentionedscheme whereby it fails all the desired and essential security attributes of asigncryption scheme.
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