The Finite Groups With the Same Degree and the Prime Number of Non-linear Irreducible Characters

对于具有素数个非线性不可约特征标且它们的维数相等的有限群,我们给出一个分类.In this paper,we classify all the finite groups which have prime number of non-linear irreducible characters and whose degrees for these non-linear irreducible characters are equal.supportedbyNaturalScienceFoundationandGZ310ofSino-GermanyAcademicCenter

Analysis and improvement of a certificateless proxy blind signature

通过对葛荣亮等人提出的无证书代理盲签名方案进行分析,从中发现该方案会引起公钥替换攻击和恶意但是被动的kgC攻击。为了解决此方案的安全性缺陷,提出了一种改进方案。分析表明,改进的新方案满足无证书代理盲签名方案的所有安全性要求,并且拥有与原方案相同的计算效率。Through the cryptanalysis of a certificateless proxy blind signature scheme proposed by Ge Rong-liang,it find that this scheme can cause the public replacement attack and malicious-but-passive KGC attack.To avoid these attacks,this paper proposed a new improved scheme.Analysis result shows that the new improved shceme satisfies the requirements of proxy blind signature scheme and has the same computational efficiency compared with the original scheme.国家自然科学基金资助项目(11261060); 福建省自然科学基金资助项目(2012J01022); 新疆研究生科研创新资助项目(XJGRI2013130

Analysis and improvement of proxy blind signature scheme based on DLP

通过对何俊杰等人提出的一个基于离散对数代理盲签名方案进行分析,从中发现该方案会引起原始签名人的公钥替换攻击。为了解决该方案的安全缺陷,提出了一种新的改进方案。分析表明,改进后的新方案可以抵抗原始签名人的公钥替换攻击,并且在基于离散对数问题下保证了代理盲签名的所有安全性要求,而且提高了效率。Through the cryptanalysis of a proxy blind signature scheme based on DLP proposed by He Jun-jie,this paper found that this scheme can cause the public replacement attack.To avoid these attacks,this paper proposed a new improved scheme.Analysis result shows that the new improved scheme can resist the original signer's public key replacement attack.It satisfies all the security requirements of proxy blind signature based on the DLP problems and improve the computation efficiency.国家自然科学基金资助项目(11261060); 福建省自然科学基金资助项目(2012J01022); 新疆研究生科研创新资助项目(XJGRI2013130

Decomposition of Cartan matrix and conjectures on Brauer character degrees

设g为有限群,n是g的正规子群.记J=J(f[n])为f[n]的JACObSOn根,I=Ann(J)={α∈f[g]|Jα=0}为J在f[g]中的零化子.本文主要研究了,根据f[g/n]和f[g]/I的CArTAn矩阵,分解f[g]的CArTAn矩阵.这种分解在CArTAn不变量和g的合成因子之间建立了一些联系.本文指出n中P-亏零块的存在性依赖于CArTAn不变量或者I在f[g]中的性质,证明了CArTAn矩阵的分解部分地依赖于b所覆盖的n中的块的性质.本文研究了b为n上的块且l(b)=1时,覆盖b的g中的块b的性质.在两类情形下,本文证明了块代数上关于brAuEr特征标次数的猜想成立,涵盖了HOlM和WIllEMS研究的某些情形.进而对HOlM和WIllEMS提出的问题给出了肯定的回答.另外,本文还给出了CArTAn不变量的一些其它结果.Let G be a finite group and N a normal subgroup of G.We denote by J = J(F [N]) the Jacobson radical of F [N] and by I = Ann(J) = {α ∈ F [G]|Jα = 0} the annihilator of J in F [G].In this paper, we study the decomposition of Cartan matrix of F [G] in terms of that of F [G/N] and F [G]/I.This decomposition establishes some connections between Cartan invariants and chief composition factors of G.We will prove that existing zero-defect p-blocks in N depend on the properties of I in F [G] or Cartan invariants.We shall demonstrate that the decomposition of Cartan matrix partly depends on properties of blocks in N covered by B.We are mainly concerned with the block B of G which covers a block b of N with l(b) = 1.In two cases, we will prove that the conjectures on Brauer character degrees hold for the block algebras, covering some cases studied by Holm and Willems.Furthermore we give an affirmative answer to the question raised by Holm and Willems in our cases.Some other results about Cartan invariants are presented here

Advances of the error-floor study of LDPC codes

低密度奇偶校验(ldPC)码在迭代译码下具有优越的性能,但是在高信噪比区呈现出误码平台(ErrOrflOOr)现象。综合分析了低密度奇偶校验码的误码平台现象及其产生的原因,重点描述了陷阱集及其对ldPC码误码平台的影响,同时阐述了估计和降低ldPC码误码平台的方法,并对今后ldPC码误码平台研究的重点和方向提出了展望。Low-density parity check(LDPC)codes are known to perform very well under iterative decoding.However,these codes often exhibit an error floor phenomenon in the high signal-to-noise(SNR)region.This paper provides a comprehensive description of the cause of the error floor phenomenon of LDPC codes.It presents a detailed description of the trapping sets,describes the methods to estimate and reduce the error floor of LDPC codes.Finally,it proposes the future development of the error floor of LDPC codes

一个基于格的环签名方案的改进

针对Wang等提出的基于格中困难问题的环签名方案不满足不可伪造性的问题,提出了一种改进的环签名方案.该方案在随机谕言模型下满足全密钥暴露下的匿名性和内部攻击下的不可伪造性.而且使用一种强陷门生成算法,保证了新的签名方案简单、高效且容易实施.国家自然科学基金(11261060

The Symmet ry of CartanM at rix

摘要　给出非分裂域上的Cartan 矩阵对称的充分必要条件. 对域F 上的对称代数A , 通过考 察其有关单模的自同态代数的维数, 确定A 的Cartan 矩阵是否对称或置换对称(当A 为quasi2 F robenius 代数). Abs tra c t　L et A be a quasi2F roben iu s algeb ra over a f ield F and C= (Cij) the Car2 tan m at rix of A. U sing endomo rph ism algeb ra of simp le modu les, the au tho r gives a suff i2 cien t and necessary condit ion of C being symm et ric o r perm u tat ion2symm et ric, acco rding to A as a symm et ric algeb ra o r a quasi2F roben iu s algeb ra. Specially w hen F is a sp lit t ing f ield of A , C is symm et ric o r perm u tat ion2symm et ric

The Symmetry of Cartan Matrix

给出非分裂域上的CArTAn矩阵对称的充分必要条件.对域f上的对称代数A，通过考察其有关单模的自同态代数的维数，确定A的CArTAn矩阵是否对称或置换对称（当A为QuASI-frObEnIuS代数）.Let A be a quasi Frobenius algebra over a field F and C=(C ij ) the Cartan matrix of A.Using endomorphism algebra of simple modules, the author gives a sufficient and necessary condition of C being symmetric or permutation symmetric, according to A as a symmetric algebra or a quasi Frobenius algebra.Specially when F is a splitting field of A, C is symmetric or permutation symmetric