摘要
针对以单圈T函数代替线性移位寄存器设计流密码的可行性,对单圈T-函数的分量函数所生成序列(第k位序列)的移位自相关性进行了研究.在移位量取第k位序列周期与2的负指数幂之积的条件下,根据单圈T函数的性质,结合自相关函数的周期特征,计算了对应的自相关函数的上界和下界.由该上下界分析知,当移位量较小时,自相关函数的取值较大,表明T函数不适合直接用作密码函数生成伪随机序列.
Autocorrelation properties of coordinate sequence generated by single cycle T-function （the kth coordinate sequence） are investigated to check whether T-functions can be the substitution of linear feed- back shift register in the design of stream ciphers. Based on single cycle T-function＇s properties and autocorrelation function＇s periodicity, the bounds of autoeorrelation functions are calculated, where the shift is equal to the period of the kth coordinate sequence multiplied by 2 to the minus power. According to the bounds, it is concluded that the smaller the shift is, the larger the value of autocorrelation functions is. As a result, T-functions are not suitable for generating pseudorandom sequences.
出处
《北京邮电大学学报》
EI
CAS
CSCD
北大核心
2011年第2期104-107,共4页
Journal of Beijing University of Posts and Telecommunications
基金
国家重点基础研究发展计划项目(2007CB311201)
国家自然科学基金项目(60673072
60803149)
西安建筑科技大学青年科技基金项目(QN0831)
关键词
密码学
伪随机序列
T函数
自相关性
非线性
cryptography
pseudorandom sequences
T-functions
autocorrelation
nonlinear
