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在密文策略的属性基加密(CP-ABE,ciphertext-policy attribute-based encryption)的基础上,使用分层的多个认证机构为用户分发私钥,一方面避免了单一认证机构形式带来的服务器负荷运行等问题,另一方面便于中央授权机构对其进行管理.另外,中央授权机构无法恢复用户的个人信息轮廓,保护了用户的隐私;用户的私钥由对应的认证机构根据随机数进行提取,中央授权机构无法获知,保护了用户私钥的安全性;在私钥提取的过程中,允许用户的属性集合之间存在重叠.该方案在判定双线性Diffie-Hellman(DBDH,decisional bilinear DiffieHellman)假设下满足IND-Set-CPA(against adaptive chosen attribute set and chosen plaintext attack)安全. 相似文献
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HIRFL—CSR实验环电子冷却装置调试 总被引:1,自引:0,他引:1
HIRFL-CSR实验环电子冷却装置采用了能够产生空心电子束的电子枪。弯曲螺线管内采用了静电偏转电极,冷却段采用了独立的高精度螺线管串联产生纵向磁场的设计。测量了沿离子束运动方向冷却段磁场分布及磁场平行度、电子枪和收集器性能、300kV高压电源相关参数。结果表明,此装置达到了预期的设计目标。: In CSRe electron cooling device, a special electron gun which can produce variable profile electron beam with different size and density distribution was adopted for decreasing ion losses. Electrostatic bending device was used for reducing electron beam losses and improving vacuum condition. The instability of the electron beam is suppressed because the secondary electrons from collector would come back to the collector in the same orbit finally. Longitudinal magnetic field with parallelism better than 10-4 was achieved by adopting of independent high precise solenoid coils at cooling section. In this case, the r.m.s deviations of the transverse magnetic field at cooling section in horizontal and vertical direction are 3.298×10-5 and 2.458×10-5 respectively. The characters of the gun and collector were investigated. The results were presented and indicate that it achieves the design purpose very well. 相似文献
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HIRFL–CSR主环电子冷却装置调试 总被引:5,自引:0,他引:5
介绍了在HIRFL–CSR主环电子冷却装置上首次设计的能够产生空心电子束的电子枪阴极. 在弯曲螺线管内采用了静电偏转电极,冷却段采用了高磁场平行度螺线管设计,在IMP与BINP的合作下完成了电子冷却装置,测量了电子束剖面及密度分布、冷却段磁场平行度、电子枪和收集器的性能,实验验证了静电偏转电极的优越性,调试结果表明实现了预期的设计目标. 相似文献
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