Among the three broad classes of Identity-Based Encryption schemes built from pairings, the exponent inversion paradigm tends to be the most efficient, but also the least extensible: currently there are no hierarchical or other known extension of IBE based on those schemes. In this work, we show that such extensions can be realized from IBE systems that conform to a certain abstraction of the e...

Abstract We propose a novel approach to check whether individual behaviour in binary-choice participation games is consistent with the restrictions imposed by symmetric models. This allows particular an assessment of how much cluster-heterogeneity model can tolerate remain its behavioural restrictions. assess our data from market-entry experiments which we analyse through lens ‘Exploration vers...

Clostridium acetobutylicum naturally produces acetone as well as butanol and ethanol. Since acetone cannot be used as a biofuel, its production needs to be minimized or suppressed by cell or bioreactor engineering. Thus, there have been attempts to disrupt or inactivate the acetone formation pathway. Here we present another approach, namely, converting acetone to isopropanol by metabolic engine...

Fujisaki-Okamoto (FOpkc) conversion [14] and REACT conversion [18] are widely known to be able to generically convert a weak public key encryption scheme to a strong encryption scheme, i.e., indistinguishable against adaptive chosen ciphertext attacks (IND-CCA). In this paper, we discuss applications of Fujisaki-Okamoto (FOpkc) conversion and REACT conversion to Identity Based Encryptions (IBE)...

The notion of extended nested dual system groups (ENDSG) was recently proposed by Hofheinz et al. [PKC 2015] for constructing almost-tight identity based encryptions (IBE) in the multi-instance, multi-ciphertext (MIMC) setting. However only a composite-order instantiation was proposed and more efficient prime-order instantiations are absent. The paper fills the blank by presenting two construct...

Identity-Based Encryption (IBE) offers an interesting alternative to PKI-enabled encryption as it eliminates the need for digital certificates. While revocation has been thoroughly studied in PKIs, few revocation mechanisms are known in the IBE setting. Until quite recently, the most convenient one was to augment identities with period numbers at encryption. All non-revoked receivers were thus ...

Deterministic public key encryption (D-PKE) provides an alternative to randomized public key encryption in various scenarios (e.g. search on encrypted data) where the latter exhibits inherent drawbacks. In CRYPTO’11, Brakerski and Segev formalized a framework for studying the security of deterministic public key encryption schemes with respect to auxiliary inputs. A trivial requirement is that ...

Exposure of a secret key is a significant threat in practice. As a notion of security against key exposure, Dodis et al. advocated key-insulated security, and proposed concrete key-insulated encryption (KIE) schemes in which secret keys are periodically updated by using a physically “insulated” helper key. For significantly reducing possibility of exposure of the helper key, Hanaoka et al. furt...

In this talk, we provide a generic transformation from any affine message authentication code (MAC) to an identity-based encryption (IBE) scheme over pairing groups of prime order. If the MAC satisfies a security notion related to unforgeability against chosen-message attacks and, for example, the k-Linear assumption holds, then the resulting IBE scheme is adaptively secure. Our security reduct...

Abstract Simple random-sampling resolutions of the raven paradox relevantly diverge from scientific practice. We develop a stratified model, yielding better fit and apparently rehabilitating simple random sampling as legitimate idealization. However, neither accommodates second concern, objection potential bias. third model that crucially invokes causal considerations, novel resolution handles ...