In this paper we describe the most important security requirements, which must be fulfilled by today's IT-systems, and the security measures used to satisfy these requirements. These security measures are based on modern cryptographic mechanisms as well as on security infrastructures. Regarding data security and communication security in particular in the field of multimedia, the requirements on security increase. If and in which way the discussed security mechanisms can be applied to multimedia security is difficult to analyse. This is mainly due to the complexity of multimedia data and their applications. This paper introduces the main issues of IT-security and represents the basis for solutions of security problems in the field of multimedia.