Public Key Encryption with Keyword Search （PEKS）, an indispensable part of searchable encryption, is stock-in- trade for both protecting data and providing operability of encrypted data. So far most of PEKS schemes ...Public Key Encryption with Keyword Search （PEKS）, an indispensable part of searchable encryption, is stock-in- trade for both protecting data and providing operability of encrypted data. So far most of PEKS schemes have been established on Identity-Based Cryptography （IBC） with key escrow problem inherently. Such problem severely restricts the promotion of IBC-based Public Key Infrastructure including PEKS component. Hence, Certificateless Public Key Cryptography （CLPKC） is efficient to remove such problem. CLPKC is introduced into PEKS, and a general model of Certificateless PEKS （CLPEKS） is formalized. In addition, a practical CLPEKS scheme is constructed with security and efficiency analyses. The proposal is secure channel free, and semantically secure against adaptive chosen keyword attack and keyword guessing attack. To illustrate the superiority, massive experiments are conducted on Enron Email dataset which is famous in information retrieval field. Compared with existed constructions, CLPEKS improves the efficiency in theory and removes the key escrow problem.展开更多
To better assimilate Advanced TIROS Operational Vertical Sounder(ATOVS) radiance data and provide more accurate initial fields for a numerical model,two bias correction schemes are employed to correct the ATOVS radian...To better assimilate Advanced TIROS Operational Vertical Sounder(ATOVS) radiance data and provide more accurate initial fields for a numerical model,two bias correction schemes are employed to correct the ATOVS radiance data.The difference in the two schemes lies in the predictors use in air-mass bias correction.The predictors used in SCHEME 1 are all obtained from model first-guess,while those in SCHEME 2 are from model first-guess and radiance observations.The results from the two schemes show that after bias correction,the observation residual became smaller and closer to a Gaussian distribution.For both land and ocean data sets,the results obtained from SCHEME 1 are similar to those from SCHEME 2,which indicates that the predictors could be used in bias correction of ATOVS data.展开更多
A new authentication scheme based on a one-way hash function and Diffie-Hellman key exchange using smart card was propused by Yoon et al. in 2005. They claimed that the proposed protocol is against password guessing a...A new authentication scheme based on a one-way hash function and Diffie-Hellman key exchange using smart card was propused by Yoon et al. in 2005. They claimed that the proposed protocol is against password guessing attack. In this paper, the author demonstrate that Yoon＇s scheme is vulnerable to the off-line password guessing attack by using a stolen smart card and the DoS attack by computational load at the re, note system. An improvement of Yoon＇s scheme to resist the above attacks is also proposed.展开更多
In the space C[-1,1],G G Lorentz proposed four conjectures on the properties of the polynomials of the best approximation in 1977,1978 and 1980.The present paper transplants the four conjectures in the space Lρ2[-a,a...In the space C[-1,1],G G Lorentz proposed four conjectures on the properties of the polynomials of the best approximation in 1977,1978 and 1980.The present paper transplants the four conjectures in the space Lρ2[-a,a] and proves them being all right in only one theorem under the corresponding conditions,although each of the original conjectures is very difficulty.展开更多
Guessing strategy is a traditional and effective way for EFL students to improve their reading. Almost all readers apply this method, to a greater or lesser extent, when reading different kinds of materials. This is p...Guessing strategy is a traditional and effective way for EFL students to improve their reading. Almost all readers apply this method, to a greater or lesser extent, when reading different kinds of materials. This is partly because readers simply do not have the time to look up every new word in the dictionary. Linguistics developments in recent years make it possible to reconsider this kind of strategy in the framework of cognitive grammar. A number of theories have provided more evidence regarding the effectiveness of a guessing strategy. Linguistic theories dealing with terms such as schemata, prototype, etc. make it possible to reconsider the strategy in a broader context. Schemata theory tells us that the context of a given word is not the only source and basis of guessing. Other factors include background knowledge and the given word itself. Prototype theory, on the other hand, shows how readers guess the meaning of a familiar word form with a completely new part of speech or meaning. Even though cognitive linguistics has shown the effectiveness of a guessing strategy in reading, the applicability of the method needs to be reconsidered. Some materials may not be suitable for the application of a guessing strategy.展开更多
基金This research was supported by the National Science Foundation of China for Funding Projects （61173089,61472298） and National Statistical Science Program of China（2013LZ46）.
文摘Public Key Encryption with Keyword Search （PEKS）, an indispensable part of searchable encryption, is stock-in- trade for both protecting data and providing operability of encrypted data. So far most of PEKS schemes have been established on Identity-Based Cryptography （IBC） with key escrow problem inherently. Such problem severely restricts the promotion of IBC-based Public Key Infrastructure including PEKS component. Hence, Certificateless Public Key Cryptography （CLPKC） is efficient to remove such problem. CLPKC is introduced into PEKS, and a general model of Certificateless PEKS （CLPEKS） is formalized. In addition, a practical CLPEKS scheme is constructed with security and efficiency analyses. The proposal is secure channel free, and semantically secure against adaptive chosen keyword attack and keyword guessing attack. To illustrate the superiority, massive experiments are conducted on Enron Email dataset which is famous in information retrieval field. Compared with existed constructions, CLPEKS improves the efficiency in theory and removes the key escrow problem.
基金National Natural Science Foundation of China (40875021, 40930951)Knowledge Innovation Program of Chinese Academy of Sciences ( KZCX2-YW-Q03-3)
文摘To better assimilate Advanced TIROS Operational Vertical Sounder(ATOVS) radiance data and provide more accurate initial fields for a numerical model,two bias correction schemes are employed to correct the ATOVS radiance data.The difference in the two schemes lies in the predictors use in air-mass bias correction.The predictors used in SCHEME 1 are all obtained from model first-guess,while those in SCHEME 2 are from model first-guess and radiance observations.The results from the two schemes show that after bias correction,the observation residual became smaller and closer to a Gaussian distribution.For both land and ocean data sets,the results obtained from SCHEME 1 are similar to those from SCHEME 2,which indicates that the predictors could be used in bias correction of ATOVS data.
文摘A new authentication scheme based on a one-way hash function and Diffie-Hellman key exchange using smart card was propused by Yoon et al. in 2005. They claimed that the proposed protocol is against password guessing attack. In this paper, the author demonstrate that Yoon＇s scheme is vulnerable to the off-line password guessing attack by using a stolen smart card and the DoS attack by computational load at the re, note system. An improvement of Yoon＇s scheme to resist the above attacks is also proposed.
文摘In the space C[-1,1],G G Lorentz proposed four conjectures on the properties of the polynomials of the best approximation in 1977,1978 and 1980.The present paper transplants the four conjectures in the space Lρ2[-a,a] and proves them being all right in only one theorem under the corresponding conditions,although each of the original conjectures is very difficulty.
文摘Guessing strategy is a traditional and effective way for EFL students to improve their reading. Almost all readers apply this method, to a greater or lesser extent, when reading different kinds of materials. This is partly because readers simply do not have the time to look up every new word in the dictionary. Linguistics developments in recent years make it possible to reconsider this kind of strategy in the framework of cognitive grammar. A number of theories have provided more evidence regarding the effectiveness of a guessing strategy. Linguistic theories dealing with terms such as schemata, prototype, etc. make it possible to reconsider the strategy in a broader context. Schemata theory tells us that the context of a given word is not the only source and basis of guessing. Other factors include background knowledge and the given word itself. Prototype theory, on the other hand, shows how readers guess the meaning of a familiar word form with a completely new part of speech or meaning. Even though cognitive linguistics has shown the effectiveness of a guessing strategy in reading, the applicability of the method needs to be reconsidered. Some materials may not be suitable for the application of a guessing strategy.
