This master's thesis deals with analysis, design and implementation of an information system that allows easy extensibility with three-tier architecture.   System is developed using object oriented approach by programming language PHP, relational database server MySQL and web services and protocol SOAP. The View tier is implemented by web technologies XHTML and CSS. Analysis and design of this system is done with using the modeling language UML.     In this thesis is described the problem of multi-tier software architecture, theory of development information's systems and described design and implementation of an information system with a three-tier architecture and it's application in the society SDC.

This thesis deals with the introduction to the security mechanism.The procedure explains the basic concepts, principles of cryptography and security of modern protocols and basic principles that are used for information transmission network. The work also describes the most common types of attacks targeting the eavesdropping of communication. The result is a design of the eavesdropping and the implementation of an attack on the secure communication of the SSL protocol..The attacker uses a false certificate and attacks based on poisoning the ARP and DNS tables for this purpose. The thesis discusses the principles of the SSL protocol and methodology of attacks on the ARP and DNS tables.