Certificateless signature: a new security model and an improved generic construction

Certificateless cryptography involves a Key Generation Center (KGC) which issues a partial key to a user and the user also independently generates an additional public/secret key pair in such a way that the KGC who knows only the partial key but not the additional secret key is not able to do any cryptographic operation on behalf of the user; and a third party who replaces the public/secret key pair but does not know the partial key cannot do any cryptographic operation as the user either. We call this attack launched by the third party as the key replacement attack. In ACISP 2004, Yum and Lee proposed a generic construction of digital signature schemes under the framework of certificateless cryptography. In this paper, we show that their generic construction is insecure against key replacement attack. In particular, we give some concrete examples to show that the security requirements of some building blocks they specified are insufficient to support some of their security claims. We then propose a modification of their scheme and show its security in a new and simplified security model. We show that our simplified definition and adversarial model not only capture all the distinct features of certificateless signature but are also more versatile when compared with all the comparable ones. We believe that the model itself is of independent interest.A conventional certificateless signature scheme only achieves Girault’s Level 2 security. For achieving Level 3 security, that a conventional signature scheme in Public Key Infrastructure does, we propose an extension to our definition of certificateless signature scheme and introduce an additional security model for this extension. We show that our generic construction satisfies Level 3 security after some appropriate and simple modification. A preliminary version of the extended abstract of partial results appeared in ACISP 2006 [9].     

丁酮分子内价轨道1a″的电子动量谱学研究

用高分辨率电子动量谱仪进行丁酮分子的结合能谱和内价轨道1a″电子动量谱的实验工作，以及用Hartree-Fock和密度泛函理论方法对1a″轨道电子动量谱的理论研究. 得到了各价轨道的电离能值以及理论计算的总能、偶极矩和1a″轨道的二维密度图. 并比较了内价轨道1a″的电子动量谱的实验和理论计算结果，实验结果与理论计算符合较好.     

Enhanced blue-green-red up-conversion and 1.3-μm emission of Pr/Yb-codoped oxyhalide tellurite glasses with PbCl2 doping

We report on the blue-green-red up-conversion spectroscopic properties of Pr³⁺/Yb³⁺-codoped oxyhalide tellurite glasses upon excitation of a conventional 980 nm laser diode (LD). Significant enhancement of the blue-green-red up-conversion emission intensity has been observed with increasing PbCl₂ doping. The up-conversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. The population of the Pr³⁺ upper ³P₀ emitting level was accomplished through a combination of a ground state absorption, energy transfer and excitated state absorption. 1.3-μm emission in the second telecom window originated from Pr³⁺:¹G₄→³H₅ transition has also been investigated upon excitation at 980 nm LD. The measured peak wavelength and full width at half-maximum of the fluorescent are 1335 nm and ∼100 nm, respectively. An enhanced 1.3μm emission with increasing PbCl₂ doping has also been observed. Codoping of Yb³⁺ significantly enhance both the blue-green-red up-conversion emission and 1.3-μm emission intensity by way of a nonradiative Yb³⁺:²F₅→Pr³⁺:¹G₄ energy transfer.     

A new method and instrument for accurately measuring interval between ultrashort pulses

Using second-order autocorrelation conception, a novel method and instrument for accurately measuring interval between two linearly polarized ultrashort pulses with real time were presented. The experiment demonstrated that the measuring method and instrument were simple and accurate (the measurement error ＜ 5 fs). During measuring, there was no moving element resulting in dynamic measurement error.     

Time-resolved Luminescence-based Chemosensor for Fluoride Anion

Design and synthesis of new chemosensors for fluoride anion (F-)1-6 have been of interest to chemists for many years, because F- plays a crucial role in the dental care5 and the treatment of osteoporosis7. Recently, the fluorescent chemosensors of fluorid…     

球形汞膜电极倒导数恒电流溶出分析法研究

本文推导并验证了球形汞膜电极倒导数恒电流溶出分析法理论。确定其理论的应用条件为汞膜厚度不超过4.6×10~(-4)cm,探讨了噪音对灵敏度的影响。     

Laser performance of monolithic Cr,Nd:YAG self-Q-switched laser

The self-Q-switched laser performance of monolithic Cr⁴⁺,Nd³⁺:YAG concave-planar resonator with 5-mm length was studied experimentally and theoretically. The slope efficiency is as high as 24% and pump threshold is as low as 64 mW. The pulse width, the single pulse energy and the pulse repetition rate of monolithic Cr,Nd:YAG self-Q-switched laser were measured as a function of absorbed pump power. With the increase of pump power, the pulse width decreases and the pulse energy and the pulse repetition rate increase. The average output power of 91 mW with pulse width of 7 ns at repletion rate of 35.5 kHz was obtained at the maximum absorbed pump power of 440 mW, the peak power is as high as 370 W. The theoretical prediction of pulse energy, pulse width and pulse repetition rate as a function of absorbed pump power based on rate equations is in a good agreement with our experimental data. This can lead to develop the diode laser-pumped monolithic self-Q-switched solid-state microchip lasers.     

未来重要光源——发光二极管

在电灯发明之后的100多年里,照明技术的不断发展使白炽灯和荧光灯面临着严重的威胁.特别是发光二极管技术的逐步成熟,引发了照明光源的一场技术革命.不仅仅是红绿灯,在大型屏幕显示、室内照明、汽车车灯、广告标志等所有需要光亮的地方,发光二极管都将取代传统的照明设备,成为未来的重要光源.     

黑卵蜂寄主识别利它素的性质研究

通过盐析、柱层析和分子筛层析，从松毛虫雌蛾附腺中分离到一种ＳＰ－Ｉ组份，经生化方法检测鉴定，此组份是一种糖蛋白，分子量为１．３５×１０５，等电点为４．２，蛋白质含量９２％，糖含量８％．它能引诱松毛虫黑卵蜂和松茸毒蛾黑卵蜂在非天然寄主上的产卵检查、刺探行为，是一种黑卵蜂寄主识别利它素．     

ON Δ-GOOD MODULE CATEGORIES OF QUASI-HEREDITARY ALGEBRAS

A useful reduction is presented to determine the finiteness of △-good module category F(△)of a quasi-heredltary algebra. As an application of the reduction, the f(△)-finitenetess of quasi-hereditary M-twisted double incidence algebras of posets is discussed. In particular, a complete classification of F(△)-finite M-twisted double incidence algebras is given in case the posets are linearly ordered.