Encrypted protocols, such as Secure Socket Layer (SSL), are becoming more prevalent because of the growing use of e-commerce, anonymity services, gaming and Peer-to-Peer (P2P) applications such as Skype and Gtalk. The objective of this work is two-fold. First, an investigation is provided into the identification of web browsing behaviour in SSL tunnels. To this end, C5.0, naive Bayesian, AdaBoost and Genetic Programming learning models are evaluated under training and test conditions from a network traffic capture. In these experiments flow based features are employed without using Internet Protocol (IP) addresses, source/destination ports or payload information. Results indicate that it is possible to identify web browsing behaviour in SSL encrypted tunnels. Test performance of ~95% detection rate and ~2% false positive rate is achieved with a C5.0 model for identifying SSL. ~98% detection rate and ~3% false positive rate is achieved with an AdaBoost model for identifying web browsing within these tunnels. Second, the identifying characteristics of SSL traffic are investigated, whereby a new tool is introduced to generate new flow statistics that focus on presenting the features in a unique way, using bins to represent distributions of measurements. These new features are tested using the best performers from previous experiments, C5.0 and AdaBoost, and increase detection rates by up to 32.40%, and lower false positive rates by as much as 54.73% on data sets that contain traffic from a different network than the training set was captured on. Furthermore, the new feature set out-preforms the old feature set in every case.

My master’s thesis is focused on designing and creating communication network, which provides communication between two independent networks through encrypted tunnel. My solution is based on routers formed by older personal computers with FreeBSD like a operating system. Between routers is created static encrypted tunnel by using IPSec protocol. Voice services provides packet oriented exchange Asterisk with support of signaling protocol SIP. This solution can be used eg. for connecting remote branch to headquarters of company and then can branch utilize shrared resources. To headquarters can connect also remote workers from their home. In this case are used SSL certificates to authentication of user. This scenario is very required today.

This master´s thesis deals with problems of certification authorities and digital signature. There are analyzed principles of digital certificates and certification authorities. It describes the the most widely used cryptosystems and hash functions, which are used in communications with certificates and digital signature. Analysis is focused on Public key infrastructure standard, which describes rules of creating of certification authority and digital signature. There is also described detailed principle of digital signature. Next chapters deals with studying of protocol SSL, principles of functions and usage of SSL. Practical part of this thesis realizes certification authority and information system. There is shown used software and configuration of it. Last part describes procedures during using aplication and her realization.

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.