The aim of this thesis is to provide comprehensive information on the possibilities of authentication, combination of authentication factors and the integration of this issue into corporate communication. The work focuses on this issue and specifies the possibilities for obtaining authentication information, analyses the authentication methods, identification and authorization. It examines the applicability of biometric technologies, the principle of their functionality, examples of their use, their impact, the advantages and disadvantages they bring. A natural, easy-to-use, convenient tool for effective and secure communication is authentication including the dynamic biometric signature. The issues of the dynamic biometric signature technology and its implementation are examined from a comprehensive perspective involving experiments. The research proved that the dynamic biometric signature can serve as a method for supporting secure corporate communication and reduce authentication risks in companies and for individuals.

No description available.

No description available.

No description available.

Voice over Internet Protocol (VoIP), also called IP telephony is rapidly becoming a familiar term and as a technology it is invading the enterprise, private usage, and educational and government organizations. Exploiting advanced voice coding & compression techniques and bandwidth sharing over packet switched networks, VoIP can dramatically improve bandwidth efficiency. Moreover enhanced security features, mobility support, and cost reduction features of VoIP are making it a popular choice for personal communication. Due to its rapid growth in popularity VoIP is rapidly becoming the next generation phone system. Lawful interception is a mean of monitoring private communication of users that are suspected of criminal activities or to be a threat to national security. However, government regulatory bodies and law enforcement agencies are becoming conscious of the difficulty of lawful interception of public communication due to the mobilitysupport and advanced security features implemented in some implementations of VoIP technology. There has been continuous pressure from the government upon the operators and vendors to find a solution that would make lawful interception feasible and successful. Key escrow was proposed as a solution by the U. S. National Security Agency. In key escrow the key(s) for a session are entrusted to a trusted third party and upon proper authorization law enforcement agencies can receive the session key(s) from this trusted third party However, key escrow adds some security vulnerabilities and potential risks as an unethical employee of the key escrow agent (or a law enforcement agency that has received the session key(s)) can misuse the key(s) to forge content of a communication session -- as he or she possesses the same key(s) as the user used for this session. This thesis addresses the issue of forged session content, by proposing, implementing, and evaluating a cryptographic model which allows key escrow session content. The implementation utilizes an existing implementation of a Session Initiation Protocol (SIP) user agent ‘minisip’ developed at KTH. The performance evaluation results suggest that the proposed model can support key escrow while protecting the user communication from being forged with the cost of minimal computational resource and negligible overhead. without the possibility of undetectable fabrication of  session content. The implementation utilizes an existing implementation of a Session Initiation Protocol (SIP) user agent ‘minisip’ developed at KTH. The performance evaluation results suggest that the proposed model can support key escrow while protecting the user communication from being forged with the cost of minimal computational resource and negligible overhead.

Forensic analysis on a media with fragmented and deleted files is a difficult task. There is a lack of tools and techniques that can accurately and quickly detect fragmented suspect files. Fragmented file data that resides in slack space is often overlooked by digital forensic tools. This thesis proposes to use a prefix signature of 4, 8, 16, or 32 bytes instead of either a complete sector comparison or a hash of the complete sector. The experiments show that the 32 byte has as much discrimination as an MD5 or SHA hash in uniquely identifying a sector. It is shown that the false positive rate does not exceed 10% for prefix signature sizes of 32, 16, and 8 bytes. Also the difference in false positive rates for the 32 and 16 byte prefixes does not exceed 25% as compared to MD5 and SHA hashes.

No description available.

No description available.

No description available.

The prevalence of the Internet, client/server applications, Java, e-commerce, and electronic communications offers tremendous opportunities for business, education and communication, while simultaneously presenting big challenges to network security. In general, the web was designed with little concern for security. Thus, the issue of security is important in the design of network-based applications. The software architecture proposed in this thesis allows for the secure and efficient running of a team-based decision support system, specifically TEAMDEC. Based on the system's requirements and architecture, three types of possible attacks to the system are identified and a security solution is proposed that allows for user authentication, secure communication, and script access control. The implementation of these features will reduce security risk and allow effective use of the valuable system information data. / Master of Science