Expressive and Secure Searchable Encryption in the Public Key Setting (Full Version)

Searchable encryption allows an untrusted server to search on encrypted data without knowing the underlying data contents. Traditional searchable encryption schemes focus only on single keyword or conjunctive keyword search. Several solutions have been recently proposed to design more expressive search criteria, but most of them are in the setting of symmetric key encryption. In this paper, based on the composite-order groups, we present an expressive and secure asymmetric searchable encryption (ESASE) scheme, which is the first that simultaneously supports conjunctive, disjunctive and negation search operations. We analyze the efficiency of ESASE and prove it is secure under the standard model. In addition, we show that how ESASE could be extended to support the range search and the multi-user setting

a secure and efficient revocation scheme for fine-grained access control in cloud storage

To keep data confidential against unauthorized cloud servers and users, cryptographic access control mechanisms must be adopted. However, user revocation is a challenging issue since it would inevitably require data re-encryption, and may need user secret key updates. Considering the complexity of fine-grained access control policy and the large number of users in cloud, this issue would become extremely difficult to resolve. In this paper, we focus on this challenging open issue and present a secure and efficient revocation scheme. We propose a modified CP-ABE algorithm to set up a fine-grained access control method, in which user revocation is achieved based on the theory of Shamir's Secret Sharing. Compared with existing schemes, our scheme introduces a minimal overhead not only to the data owner but also to cloud servers. Collusions between cloud servers and revoked users can be avoided as long as the key-update protocol is honestly executed. Meanwhile, the data owner can delegate key updates to the cloud servers without disclosing data contents, user attributes, and the access policy information. Moreover, our scheme maintains the important feature that the revocation won't affect the users whose attribute set is a superset of the revoked user's. © 2012 IEEE.Quanta Computer; MEDIATEK; Microsoft; Institute for Information Industry; Industrial Technology Research Institute (ITRI)To keep data confidential against unauthorized cloud servers and users, cryptographic access control mechanisms must be adopted. However, user revocation is a challenging issue since it would inevitably require data re-encryption, and may need user secret key updates. Considering the complexity of fine-grained access control policy and the large number of users in cloud, this issue would become extremely difficult to resolve. In this paper, we focus on this challenging open issue and present a secure and efficient revocation scheme. We propose a modified CP-ABE algorithm to set up a fine-grained access control method, in which user revocation is achieved based on the theory of Shamir's Secret Sharing. Compared with existing schemes, our scheme introduces a minimal overhead not only to the data owner but also to cloud servers. Collusions between cloud servers and revoked users can be avoided as long as the key-update protocol is honestly executed. Meanwhile, the data owner can delegate key updates to the cloud servers without disclosing data contents, user attributes, and the access policy information. Moreover, our scheme maintains the important feature that the revocation won't affect the users whose attribute set is a superset of the revoked user's. © 2012 IEEE

LPS Pretreatment Attenuates Cerebral Ischaemia/Reperfusion Injury by Inhibiting Inflammation and Apoptosis

Background/Aims: Lipopolysaccharide (LPS) pretreatment has a strong neuroprotective effect on cerebral ischaemia/reperfusion injury (IRI), but the mechanism has not been fully elucidated to date. This study investigated the effect of LPS pretreatment on the pathway mediated by endoplasmic reticulum (ER) stress–CCAAT/enhancer-binding protein- homologous protein (CHOP) and the role of this pathway on cerebral ischaemia/reperfusion (I/R)-induced inflammation and apoptosis. Methods: Healthy male BALB/c mice were randomised into four groups as follows: sham operation group (sham group, n=30); LPS group (BALB/c mice treated with LPS, n=30); ischaemia/reperfusion group (I/R group, n=30) and I/R+LPS group (BALB/c mice treated with LPS before ischaemia, n=30). The mice were pre-treated with LPS (0.2 mg/kg) intra-peritoneally for three days prior to cerebral ischaemia. After 24 hours, the neurological deficit score, TTC staining and TUNEL assay were used to assess the neuroprotective effect of the LPS pretreatment against cerebral IRI. To assess whether the ER stress-CHOP pathway participated in the LPS-pretreatment neuroprotective mechanism, the expression levels of related proteins (GRP78, CHOP, caspase-12 and caspase-3) from the ischaemic cortical penumbra were detected via a western blot analysis. An immunohistochemical study was used to detect the expression and location of CHOP in the cortical penumbra. To further assess the protective effect of the LPS pretreatment, the concentrations of inflammatory factors (TNF-α, IL-6, IL-1β and IL-10) in the cortical penumbra were measured by ELISA, and ER stress-CHOP pathway inflammation-related caspase-11 was analysed through western blot analysis. Results: As demonstrated by the experiments, the pretreatment with LPS significantly reduced the neurological deficit score and the infarct size of cerebral IRI. The expression levels of ER stress-CHOP pathway related proteins (GRP78, CHOP, caspase-12 and caspase-3) from the cortical penumbra were significantly decreased by LPS, as well as the level of apoptosis in the cells in the brain. Immunohistochemistry showed that the expression of CHOP significantly decreased after the LPS pretreatment. Furthermore, the concentrations of inflammatory factors (TNF-α, IL-1β, IL-6) were reduced after the LPS pretreatment, whereas the anti-inflammatory cytokine IL-10 was upregulated. In addition, ER stress-CHOP pathway inflammation-related caspase-11 expression was significantly suppressed after the pretreatment with LPS. Conclusions: LPS pretreatment significantly ameliorates the effects of cerebral IRI by inhibiting inflammation and apoptosis, and the potential mechanism of the neuroprotective effect may be associated with the ER stress-CHOP mediated signalling pathway

Cross-linked polyaniline for production of long lifespan aqueous iron||organic batteries with electrochromic properties

Abstract Aqueous iron batteries are appealing candidates for large-scale energy storage due to their safety and low-cost aspects. However, the development of aqueous Fe batteries is hindered by their inadequate long-term cycling stability. Here, we propose the synthesis and application as positive electrode active material of cross-linked polyaniline (C-PANI). We use melamine as the crosslinker to improve the electronical conductivity and electrochemical stability of the C-PANI. Indeed, when the C-PANI is tested in combination with a Fe metal negative electrode and 1 M iron trifluoromethanesulfonate (Fe(TOF)2) electrolyte solution, the coin cell can deliver a specific capacity of about 110 mAh g−1 and an average discharge voltage of 0.55 V after 39,000 cycles at 25 A g−1 with a test temperature of 28 °C ± 1 °C. Furthermore, mechanistic studies suggest that Fe2+ ions are bonded to TOF− anions to form positively charged complexes Fe(TOF)+, which are stored with protons in the C-PANI electrode structures. Finally, we also demonstrate the use of C-PANI in combination with a polymeric hydrogel electrolyte to produce a flexible reflective electrochromic lab-scale iron battery prototype