Abstract: An optimization mathematical model and an algorithm of complexification of the measures providing information security are presented. As an indicator of complexification efficiency, the level of the costs of execution of the tasks of providing the information security of a protected object is used. Thus, the costs of the elaboration (preparation) of these measures and their implementation costs for the information security system are considered separately. The optimization algorithm is based on the common principles of the branch and bound method. Its feature is the proposed algorithm for estimating the bounds for alternative branches. The model has a universal character and may be used when developing the algorithms for supporting the corresponding management decisions concerning information security for concrete information infrastructures of managerial-technical, social, economic, and other objects. © 2020, Allerton Press, Inc.