Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits....Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.展开更多
Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized ma...Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized management and transmission latency of the cloud makes it difficult to support real-time processing and distributed access structures.As a result,fog computing and the Internet of Things(IoT)have emerged as crucial applications.Fog-assisted proxy re-encryption is a commonly adopted technique for sharing cloud ciphertexts.It allows a semitrusted proxy to transforma data owner’s ciphertext into another re-encrypted ciphertext intended for a data requester,without compromising any information about the original ciphertext.Yet,the user revocation and cloud ciphertext renewal problems still lack effective and secure mechanisms.Motivated by it,we propose a revocable conditional proxy re-encryption scheme offering ciphertext evolution(R-CPRE-CE).In particular,a periodically updated time key is used to revoke the user’s access privileges while an access condition prevents a malicious proxy from reencrypting unauthorized ciphertext.We also demonstrate that our scheme is provably secure under the notion of indistinguishability against adaptively chosen identity and chosen ciphertext attacks in the random oracle model.Performance analysis shows that our scheme reduces the computation time for a complete data access cycle from an initial query to the final decryption by approximately 47.05%compared to related schemes.展开更多
Two 1-methyl-1H-benzo[d]imidazole derivatives, C_（18）H_（14）CuN_4O_4·C_4H_8O_2（1） and C_9H_9N_3O（2）, have been synthesized and characterized by NMR, MS, FT-IR, elementary analysis and X-ray single-crystal ...Two 1-methyl-1H-benzo[d]imidazole derivatives, C_（18）H_（14）CuN_4O_4·C_4H_8O_2（1） and C_9H_9N_3O（2）, have been synthesized and characterized by NMR, MS, FT-IR, elementary analysis and X-ray single-crystal diffraction. Compound 1 crystallizes in monoclinic, space group P2_1/n with a = 9.6888（3）, b = 7.3772（2）, c = 14.3277（4）A, β = 95.819（3）°, V = 1018.81（5） A3, M_r = 501.98, Z = 2, D_c = 1.636 g/cm^3, F（000） = 518, μ = 1.123 mm^（-1）, MoKα radiation（λ = 0.71073 A）, the final R = 0.0325 and wR = 0.0859 for 1821 observed reflections with I 〉 2σ（I）. Compound 2 crystallizes in monoclinic, space group C2/c with a = 14.2908（14）, b = 14.4268（13）, c = 8.4802（6） A, β = 108.513（9）o, V = 1657.9（3） A3, M_r = 175.19, Z = 8, D_c = 1.404 g/cm^3, F（000） = 736, μ = 0.097 mm^（-1）, Mo Kα radiation（λ = 0.71073 A）, the final R = 0.0563 and wR = 0.1531 for 1231 observed reflections with I 〉 2σ（I）. Intermolecular（N-H···N, N-H···O） and intramolecular（N-H···N, C-H···O） hydrogen bonds, as well as C-H···π and π-π stacking interactions, help to stabilize the crystal structure of compound 2.展开更多
基金Project (No. 200442) supported by the Electronics DevelopmentFoundation for the Key Industrialization Project of the Ministry of0Information Industry, China
文摘Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.
基金supported in part by the National Science and Technology Council of Republic of China under the contract numbers NSTC 114-2221-E-019-055-MY2NSTC 114-2221-E-019-069.
文摘Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized management and transmission latency of the cloud makes it difficult to support real-time processing and distributed access structures.As a result,fog computing and the Internet of Things(IoT)have emerged as crucial applications.Fog-assisted proxy re-encryption is a commonly adopted technique for sharing cloud ciphertexts.It allows a semitrusted proxy to transforma data owner’s ciphertext into another re-encrypted ciphertext intended for a data requester,without compromising any information about the original ciphertext.Yet,the user revocation and cloud ciphertext renewal problems still lack effective and secure mechanisms.Motivated by it,we propose a revocable conditional proxy re-encryption scheme offering ciphertext evolution(R-CPRE-CE).In particular,a periodically updated time key is used to revoke the user’s access privileges while an access condition prevents a malicious proxy from reencrypting unauthorized ciphertext.We also demonstrate that our scheme is provably secure under the notion of indistinguishability against adaptively chosen identity and chosen ciphertext attacks in the random oracle model.Performance analysis shows that our scheme reduces the computation time for a complete data access cycle from an initial query to the final decryption by approximately 47.05%compared to related schemes.
基金Supported by the National Natural Science Foundation of China(No.31370373 and 21102084)Natural Science Foundation of Hubei Province(No.2012FKC14401)
文摘Two 1-methyl-1H-benzo[d]imidazole derivatives, C_（18）H_（14）CuN_4O_4·C_4H_8O_2（1） and C_9H_9N_3O（2）, have been synthesized and characterized by NMR, MS, FT-IR, elementary analysis and X-ray single-crystal diffraction. Compound 1 crystallizes in monoclinic, space group P2_1/n with a = 9.6888（3）, b = 7.3772（2）, c = 14.3277（4）A, β = 95.819（3）°, V = 1018.81（5） A3, M_r = 501.98, Z = 2, D_c = 1.636 g/cm^3, F（000） = 518, μ = 1.123 mm^（-1）, MoKα radiation（λ = 0.71073 A）, the final R = 0.0325 and wR = 0.0859 for 1821 observed reflections with I 〉 2σ（I）. Compound 2 crystallizes in monoclinic, space group C2/c with a = 14.2908（14）, b = 14.4268（13）, c = 8.4802（6） A, β = 108.513（9）o, V = 1657.9（3） A3, M_r = 175.19, Z = 8, D_c = 1.404 g/cm^3, F（000） = 736, μ = 0.097 mm^（-1）, Mo Kα radiation（λ = 0.71073 A）, the final R = 0.0563 and wR = 0.1531 for 1231 observed reflections with I 〉 2σ（I）. Intermolecular（N-H···N, N-H···O） and intramolecular（N-H···N, C-H···O） hydrogen bonds, as well as C-H···π and π-π stacking interactions, help to stabilize the crystal structure of compound 2.
