Libor Dostálek was born in 1957 in Prague, Europe. He graduated in mathematics at the Charles University in Prague. Since last 20 years he has been involved in ICT architecture and security. His experiences as the IT architect and the hostmaster of one of the first European Internet Service Providers have been used while writing this publication. Later he became an IT architect of one of the first home banking applications fully based on the PKI architecture, and also an IT architect of one of the first GSM banking applications (mobile banking). As a head consultant, he designed the architecture of several European public certification service providers (certification authorities) and also many e-commerce and e-banking applications. The public knows him either as an author of many publications about TCP/IP and security or as a teacher. He taught at various schools as well as held various commercial courses. At present, he lectures on Cryptology at the Charles University in Prague. Nowadays, he is an employee of Siemens. Alena Kabelová was born in 1964 in Budweis, Europe. She graduated in ICT at the Economical University in Prague. She worked together with Libor Dostálek as a hostmaster. She is mostly involved in development and schooling of software. At present, she works as a senior project manager at the PVT and focuses mainly on electronic banking. Her experiences as the hostmaster of an important European ISP are applied in this publication.