Cryptanalysis of Lu et al.'s Proxy Blind Multi Signature Scheme

Abstract

Abstract-As a variation of ordinary digital signature scheme, a proxy signature scheme able a proxy signer to sign messages on behalf of the original signer. Proxy multi-signature is an extension of the basic proxy signature primitive and permits two or more entities to delegate their signing capabilities to the same other entity. In proxy multi-signature, many original signers can delegate their signing power to a proxy signer in such a way that the proxy signer can sign any message on behalf of original signers. In blind signature, the signer cannot make a linkage between the blind signature and the identity of the requester. Proxy blind multi-signature is the combination of proxy multi-signature and blind signature. Recently, Lu et al. presented a proxy blind multi-signature scheme which did not need a secure channel. However, in this paper, we show that Lu et al.'s scheme does not satisfy the unforgeability and also shown that their scheme is not secure against the original signer's forgery attack and the proxy signer's forgery attacks.Index Terms-Blind signature, proxy-multi signature, proxy blind multi signature, security.

57Fe Mössbauer studies across the spin density wave transition in BaFe2−xRuxAs2

“…The phase diagram based on resistivity data of our samples [25] is consistent with earlier reports on single crystals [26,27]. Recently we have carried out the structural characterization of the present single crystals both at room temperature and across the tetragonal to orthorhombic transition, using synchrotron x-ray diffraction measurements [28]. The Mössbauer measurements were carried out at room temperature and at 5 K for various Ru fractions (x = 0.0-0.5).…”

“…Thus, the increase in the IS implies that the conduction electron density changes significantly with Ru substitution. As a function of Ru substitution, it was seen from our local structure investigations that the position of the As atom in the unit cell (Z As ) decreases and the Fe-As bond length increases [28]. The increase in IS could be on account of the increase in Fe-As bond length due to Ru substitution.…”

“…However, these studies had not explored a systematic composition dependence of the onset of local B hf , as done here. If we plot the temperature of the onset of B hf (see figure 9), it is seen that this circumscribes the established phase boundary corresponding to the orthorhombic/SDW in BaFe 2−x Ru x As 2 [4,28]. In this plot, we have also included data for x = 0 from experiments by Rotter et al [35].…”

“…The variation in isomer shift (IS) and the individual B hf corresponding to the three components of trimodal distribution and the averaged B hf are plotted as a function of temperature in figures 6(b)-(d). In figure 6(a) the variation of the orthorhombic distortion obtained in the same sample as a function of temperature from high resolution synchrotron xray diffraction measurements as reported in [28] is shown. It is evident from figure 6(b) that the IS tracks the structural transition viz.…”

Forgery attacks of an identity‐based multi‐proxy signature scheme

“…Recently, a number of proxy signature constructions and the attacks had been proposed. Readers may refer to for more details on proxy signature schemes.…”