Non-Transferable Proxy Re-Encryption Scheme for Data Dissemination Control

A proxy re-encryption (PRE) scheme allows a proxy to re-encrypt a ciphertext for Alice (delegator) to a ciphertext for Bob (delegatee) without seeing the underlying plaintext. With the help of the proxy, Alice can delegate the decryption right to any delegatee. However, existing PRE schemes generally suffer from at least one of the followings. Some schemes fail to provide the non-transferable property in which the proxy and the delegatee can collude to further delegate the decryption right to anyone. This is the main open problem left for PRE schemes. Other schemes assume the existence of a fully trusted private key generator (PKG) to generate the re-encryption key to be used by the proxy for re-encrypting a given ciphertext for a target delegatee. But this poses two problems in PRE schemes if the PKG is malicious: the PKG in their schemes may decrypt both original ciphertexts and re-encrypted ciphertexts (referred as the key escrow problem); and the PKG can generate re-encryption key for arbitrary delegatees without permission from the delegator (we refer to it as the PKG despotism problem). In this paper, we propose the first non-transferable proxy re-encryption scheme which successfully achieves the non-transferable property. We also reduce the full trust in PKG, only a limited amount of trust is placed in the proxy and PKG. We show that the new scheme solved the PKG despotism problem and key escrow problem as well. Further, we find that the new scheme satisfies requirements of data dissemination control which is also a challenging goal for data security. We explore the potential of adopting our new scheme to achieve data dissemination control and implement a non-transferable re-encryption based encrypted PC/USB file system. Performance measurements of our scheme demonstrate that non-transferable re-encryption is practical and efficient

Use of a quasi-Newton method in a feedforward neural network construction algorithm

10.1109/72.363426IEEE Transactions on Neural Networks61273-277ITNN

Some n-bit parity problems are solvable by feed-forward networks with less than n hidden units

Proceedings of the International Joint Conference on Neural Networks1305-30885OF

Randomized competitive algorithms for successful and unsuccessful search

Computer Journal395427-438CMPJ

SPCS: Secure and Privacy-Preserving Charging-Station Searching Using VANET

Electric vehicle has attracted more and more attention all around the world in recent years because of its many advantages such as low pollution to the environment. However, due to the limitation of current technology, charging remains an important issue. In this paper, we study the problem of finding and making reservation on charging stations via a vehicular ad hoc network (VANET). Our focus is on the privacy concern as drivers would not like to be traced by knowing which charging stations they have visited. Technically, we make use of the property of blind signature to achieve this goal. In brief, an electric vehicle first generates a set of anonymous credentials on its own. A trusted authority then blindly signs on them after verifying the identity of the vehicle. After that, the vehicle can make charging station searching queries and reservations by presenting those signed anonymous credentials. We implemented the scheme and show that the credential signing process (expected to be the most time consuming step) can be completed within reasonable time when the parameters are properly set. In particular, the process can be completed in 5 minutes when 1024 bits of RSA signing key is used. Moreover, we show that our scheme is secure in terms of authentication and privacy-preserving

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally