A MODEL OF SOFTWARE CRYPTOGRAPHY SYSTEM FOR DATA PROTECTION IN DISTRIBUTION INFORMATION SYSTEMS Dr. Veselin Tselkov State Commission on Information Security And Dr. Nikolai Stoianov Defence Advanced Research Institute Abstract: This paper presents a model of software cryptography system for data protection in Distribution Information Systems. The architecture, functional features and components of the system are explained. The solutions for files, e-mail end web protection are presented. The solutions comprise the authors’ experience in development and implementation of systems for information security in the Automated Information Systems of Bulgarian Armed Forces. Keywords: computer security, information security, cryptography, cryptographic software, data protection, file security, e-mail security, web security. 1. INTRODUCTION The development of Internet as the biggest world network puts it in the basis of the Information Society. The number of corporate systems based on the Internet technologies is gradually increasing. This leads to a rise in the treats and attacks to the corporate Intranets. That's why the problems of security become more serious and more actual. The architecture of a corporate Intranet consists of nodes (local networks from workstations, servers, and communication devices) and internoding communications [3]. We can point out development of defensive technologies such as: • firewalls; • virtual private networks (VPNs); • traffic management; • network management and audit; • applications management and audit; • intrution detection systems; • identification and authentication; • encryption. Cryptographic algorithms and mechanisms (symmetrical and asymmetrical) are the basis of almost all defensive technologies. In a significant part of commercially distributed products and technologies there are either government restrictions on the use of cryptographic mechanisms (for example, there are restrictions to the length of the keys in the United States) or necessity of receiving special licenses allowing their purchase [5, 6]. The requirements for using their own cryptographic systems are needed for corporations with top secret data. CSSW is a solution for cryptographic software to protect the information in a corporate Intranet.