对一个无证书盲签名方案的攻击与改进

对黄茹芬等提出的一个高效的无证书盲签名方案进行了安全性分析,指出方案不能抵抗公钥替换攻击.为此,提出了一个改进方案.改进方案在随机预言模型和计算Diffie-Hellman(CDH)问题、q-强Diffie-Hellman(q-SDH)问题及逆计算Diffie-Hellman(inv-CDH)问题困难的假设下对适应性选择消息和身份攻击是存在不可伪造的.     

Methyl orbital signatures in 2-amino-l-propanol

Electron density distributions of 2-aminoethanol （2AE） and 2-amino-l-propanol （2AP） are calculated in both the coordinate and the momentum spaces using the B3LYP/TZVP method. Using the dual space analysis, molecular orbital signatures of the methyl substituent in 2AP are identified with respect to 2AE. Relaxations of the geometry and the valence orbital in 2AP are found to be due to the insertion of the methyl group. Five orbitals, not four orbitals, are identified as the methyl signatures. They are orbital 5a in the core shell, orbitals 9a and 10a in the inner valence shell, and orbitals 15a and 16a in the outer valence. In the inner valence shell, the attachment of methyl to 2AE causes a splitting of its orbital 8a into orbitals 9a and 10a of 2AP, whereas in the outer valence shell, the methyl group results in the insertion of an additional orbital pair of 15a and 16a. The frontier molecular orbitals 21a, 20a, and 19a are found to have no significant role in the methylation of 2AE.     

Signature splitting of the πh11/2 band and high-spin structures in 155Tb

Seven experimentally observed bands of 155Tb are analyzed in detail,using the particle-number-conserving method for treating the cranked shell model with monopole and quadrupole pairing interactions.We satisfactorily reproduce the experimental alignments and especially focus on the microscopic mechanism of the second back-bending and the influence of pair interaction on ultrahigh spins.Our calculated results show that the πi13/2 orbitals are too high to give a contribution to the moment of inertia below ω≈ 0.7 MeV.Instead,the crossing between the π[541]1/2 and other proton orbitals is responsible for the second back-bending.We assign a possible configuration to the decoupled band found in 155Tb and predict eleven bands which are experimentally unobserved.     

Proposed Chiral Doublet Bands in ^98Tc

High spin states in odd-odd ^98 Tc nuclei are studied by in-beam γ-ray spectroscopy with the ^96 Zr（^6Li, 412） fusionevaporation reaction at a beam energy of 35MeV. The previous level scheme is updated. A band based on 1090.7keV is expanded, and another band based on 1920.6 keV is newly identified. The observed two negative parity bands in ^98 Tc are proposed to be a pair of chiral doublet bands with the configuration πg9/2 vh11/2. The evidence supporting the assignment of the chiral doublet bands is discussed. Signature splitting and signature inversion are observed in the πg9/2 vh11/2 band in ^98Tc.     

Scalable Arbitrated Quantum Signature of Classical Messages with Multi-Signers

Unconditionally secure signature is an important part of quantum cryptography. Usually, a signature scheme only provides an environment for a single signer. Nevertheless, in real applications, many signers may collaboratively send a message to the verifier and convince the verifier that the message is actually transmitted by them. In this paper, we give a scalable arbitrated signature protocol of classical proved to be secure even with a compromised arbitrator. messages with multi-signers. Its security is analyzed and proved to be secure even with a compromised arbitrator.     

基于ID的一次性盲公钥的密码学分析

为保护用户的隐私又可以避免用户犯罪,ZHANG等提出了基于ID的一次性盲公钥协议.本文给出了两种伪造攻击方案,任何注册用户和非注册用户都可以伪造私钥和证书并可以对任何消息产生有效的签名,而可信中心无法在法院授权的情况下揭示签名者的真实身份,从而指出他们的方案无法阻止用户犯罪,而且是全局可伪造的.     

车载自组网下分布式身份认证机制

针对车载自组网中存在的安全隐患,提出一种身份认证机制.将门限RSA签名技术应用到车载自组网中,从而保证了车载自组网中节点通信信息的保密性、真实性、完整性及不可否认性.实验结果表明,在成员数量和门限值不断变换下,分发时间和合成时间变换比较稳定,说明此模型是稳定性较好的模型,所以将门限RSA签名技术应用于保证车载自组网节点通信的信息安全性是正确可行的.     

一种新的具有已知签名者的门限代理签名方案

利用双线性对理论和可验证的秘密分享技术，提出了一种新的具有已知签名者的门限代理签名方案．该方案通过在门限代理签名中引入实际参与签名的t个代理签名人的身份标志集合，解决了原有方案中门限代理签名方案中不具备强可识别性的问题；并利用双线性对的优点，克服了同类方案中存在的不能抵抗联合攻击和原始签名人伪造攻击等安全漏洞．结果表明：与同类方案相比，新方案的运算效率约提高20％，签名长度约缩短25％．     

无可信中心下基于身份的门限签名方案

考虑到很多门限签名方案都不抵抗恶意PKG攻击的事实,本文提出了一个无可信中心下基于身份的门限签名方案,避免了该类型攻击.在该方案中,每一个签名参与者都可以验证公钥和公钥份额的合法性,从而避免了公钥份额替换攻击.给出了无可信中心下基于身份的门限签名方案不可伪造性的安全模型,并利用此安全模型给出了该方案在标准模型下的安全性证明.