中文摘要：

In order to measure the ton＇elation propeties of two Boolean tunctions, the global avalanche characteristics of Boolean functions constructed by concatenation are discussed, i.e., f1｜｜f2 and f1｜｜f2 ｜｜f3｜｜f4. Firstly, tor the tunction f = f1｜｜f2, the cross-correlation tunction of f1,f2 in the special condition are studied. In this case, f, f1, f2 must be in desired form. By computing their sum-of-squares indicators, the cross- correlation function between f1, f2 is obtained. Secondly, tor the tunction g = f1｜｜f2｜｜f3 ｜｜f4, by analyzing the relation among their auto-correlation tunctions, their sum-of-squares indicators are investigated. Based on them, the sum-of-squares indicators of functions obtained by Canteaut et al. are investigated. The results show that the correlation property of g is good when the ton＇elation propeaies of Boolean tunctions f1, f2, f3, f4 are good.