The article deals problems with the security of software for Intelligent Transport systems that form the basis of national digital economies and critical information infrastructures. An extended system of software security criteria has been proposed, issues of confidence in its security have been considered. A method of software security is proposed, based on the integration of information security requirements and technological independence of software. An example of the implementation of the proposed methodology for ensuring the security of digital economy objects and critical information infrastructures is presented. An example of the implementation of the proposed methodology for ensuring the security of digital economy objects and critical information infrastructures is presented.