Efficient and secure attribute-based signature for monotone predicates

Attribute-based signature (ABS) is a novel cryptographic primitive, which can make the signing party sign a message with fine-grained control over identifying information. ABS only reveals the fact that the verified message must be signed by a user with a set of attributes satisfying a predicate. Thus, ABS can hide any identifying information and make fine-grained control on signing. Presently, many attribute-based signature schemes have been proposed, but most of them are not very efficient. Maji et al. recently presented a complete definition and construction about ABS for monotone predicates and showed three instantiations under their framework for ABS. Although the most practical one of their instantiations is efficient, the instantiation is constructed in the generic group model and has been proved to be insecure. Then, Okamoto et al. proposed an attribute-based signature scheme in the standard model, which can support generalized non-monotone predicates over access structure. However, their scheme is not efficient in practice. In this paper, we present a framework for ABS and show a detailed security model for ABS. Under our framework, we present an attribute-based signature scheme for monotone predicates in the standard model, where we choose the Waters’ signature scheme as the prototype of our attribute-based signature scheme. Compared with the Maji’s scheme in the generic group model, the proposed scheme is constructed in the standard model. Furthermore, compared with the Okamoto’s scheme, the proposed scheme is more efficient by decreasing the computation cost.

A review of employment relations theories and their application

New developments in the industrial relations and human resource management have moved management and employee bargaining down to the level of the firm. In doing so they have generated a growing level of interest in the conduct of employment relations, not just at the level of specialist managers, who have traditionally had the responsibility for dealing with issues in this area, but across management as a whole. There is thus a growing need for managers to place more emphasis on achieving a greater symmetry between commercial objectives and employment practices. This paper looks at the predicates of managerial authority and its legitimacy, and how personal assumptions and value systems (i.e., ‘frames of reference’) held by managers can predispose them to view the nature of work and workplace relations in particular ways. The paper also presents
and aligns a range of contemporary theories within the province of such systems, with the aim being to show how judgements made about the worth or otherwise of a given range of theories are inevitably shaped by the type of value system and set of assumptions one holds towards the
world of work. The paper concludes by offering a practical guide to managers on how to evaluate their own assumptions and value systems when applying the noted theories and concepts to real world circumstances. In doing so, the paper provides a tool kit of theories and concepts that should allow managers to avoid engaging in workforce management practices that are either illconceived or based on intuitive premises.

Temporal asymmetry and the self/person split

Derek Parfit’s discussion of our bias towards the future has sparked considerable discussion of our pervasively asymmetrical attitudes towards past and future goods. Much of this discussion has centred on whether we can rationally justify such attitudes or whether they are intrinsically irrational. This paper seeks neither to justify nor to reject temporally asymmetrical attitudes, but to explicate the way perspective, and particularly temporal perspective, operates in such biases, in order to show how our temporal biases point to something important about the structure of selfhood. By employing an emerging distinction in the personal identity literature between the ‘self’ as an intrinsically first personal and temporally indexical locus of consciousness, and the ‘person’ as a diachronic bearer of various forms of physical and psychological predicates, we can see that the clash between temporally asymmetrical attitudes and symmetrical welfare judgments is in fact a result of the ways in which selves and persons interact.