• ETRI Journal
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• v.34 no.2
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• pp.235-244
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• 2012

An identity-based strong designated verifier signature scheme provides restricted verifiability only for a verifier designated by a signer and proper privacy for the signer. In this paper, we show that strong designated verifier signature schemes do not satisfy the self-unverifiability requirement in the sense that not only exposure of the verifier's secret key but also of the signer's secret key enables an attacker to verify signatures, which should have been the exclusive right of the verifier. We also present a generic method to construct a strong identity-based designated verifier signature scheme with self-unverifiability from identity-based key encapsulation and identity-based key sharing schemes. We prove that a scheme constructed from our method achieves unforgeability, non-transferability, and self-unverifiability if the two underlying components are secure. To show the advantage of our method, we present an example that outputs short signatures and we analyze its performance.

• The Journal of Society for e-Business Studies
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• v.22 no.2
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• pp.99-121
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• 2017

Standard makers in both private and public sectors have been increasingly mandating security standards upon organizations to protect organizational digital assets. A major issue in security standardization is that standards often cannot regulate all possible security efforts by the standard maker because some efforts are unverifiable by nature. This paper studies from an analytical perspective how a standard maker should design the standard using a verifiable security control in the presence of another related unverifiable one. We compare it with two benchmark standards; $na{\ddot{i}}ve$-standard which refers to the standard maker who ignores the existence of the unverifiable control, and complete-information standard which refers to the maker sets standards on both controls. Optimal standard and benchmark standard depend critically on how the two controls are configured. Under parallel configuration, the existence of the unverifiable control induces the policy maker to set a higher standard (the complete-information standard is optimal); under serial configuration, a lower standard is applied (neither benchmark works). Under best-shot configuration and if the verifiable control is more cost-efficient, the existence of the unverifiable control has no impact on the optimal standard (the $na{\ddot{i}}ve$ standard is optimal).