Design And Implementation Of Software Licensing System Based On Public Key Cryptosystem

With the increasing improvement of the network environment, software developers often use encryption technology to protect the software from the illegal use. On the one hand, however, with more and more functions and modules of software and personalized demands of software users, pure software protection function has been unable to meet the demand of electronic distribution, upgrade, tracking, management and on-demand sales; On the other hand, software encryption based on hardware encryption products of encryption lock (soft dog) has not only brought the cost of manufacturing, logistics, installation and maintenance on hardware, but also been easy to break through the hardware replication. Moreover, once they are cracked, software could be mass-produced and be difficult to remedy, so as to losing the significance of software protection.In order to address these problems effectively, software licensing of no-hardware, networking and informatization is the trend in the future. Through the construction of software licensing system, to meet the protecting requirements of product which is researched and developed independently by organizations. The paper uses famous software encryption technology, combining one of the most influential encryption algorithm globally with mixed algorithm which is custom and rather complex, which makes the system high safety and reliability. As using the modular architecture, the system has high hierarchical structure and scalabilityThe paper first analyzes the background of software protection industry on the content and the organizational structure, and software licensing system development at home and abroad as well. We put forward the existing problems and illustrate the significance of the study on this subject.Second, we study public key cryptosystem and key techniques, introduces the encryption algorithms which are commonly used in software protection technology, analysis the principle and implementing process of public key cryptosystems, as well as authorized certificate in the application of the software licensing system and method of getting computer machine code on Windows platform to bind the identity of users.Then according to the situation of the development of the software licensing technology, as well as the actual characteristics of the product of our organization, the paper makes a detail design about the scheme and the technology of system. In system design stage, we use modular design, which makes the system better hierarchy and extensibility. During the implementation phase, the paper introduces four main functional modules, including encryption, authorized certificate control, authorized certificate check and user management. Finally the paper has made the multiple-angle tests to this system and carried out test results. The results of tests show that by license certificates, software licensing system based on public key cryptosystem can not only protect the software copyright, prevent software from illegal copy and using, but also can authorize software according to customers’requirements to protect software, such as the number of grant, license deadline, function module and so on, so as to protecting the software developers on copyright and economic benefits. Finally, the author makes a conclusion to this whole paper and proposes the expectation of future research.