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Lecture Network security: Chapter 23 - Dr. Munam Ali Shah

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In previous lecture we explored the limitations of the centralized key distribution and have explored key distribution in a decentralized fashion. We discussed in detail, how message authentication could be achieved. There are several functions and protocols used for message authentication. This chapter you would be able to present an understanding of the higher level message authentication mechanism, demonstrate knowledge about different protocols used for message authentication. | Network Security Lecture 23 Presented by: Dr. Munam Ali Shah Part – 2 (e): Incorporating security in other parts of the network Summary of the Previous Lecture In previous lecture we explored the limitations of the centralized key distribution and have explored key distribution in a decentralized fashion. We discussed in detail, how message authentication could be achieved. There are several functions and protocols used for message authentication Message Authentication Mechanism classification: Message encryption MAC Hash Outlines of today’s lecture Digital signature and authentication protocols Problems in message authentication Different protocols for message authentication will be studied Digital Signature Standard (DSS) and Digital Signature Algorithm (DSA) will be explored Objectives You would be able to present an understanding of the higher level message authentication mechanism. You would be able demonstrate knowledge about different protocols used for message authentication . | Network Security Lecture 23 Presented by: Dr. Munam Ali Shah Part – 2 (e): Incorporating security in other parts of the network Summary of the Previous Lecture In previous lecture we explored the limitations of the centralized key distribution and have explored key distribution in a decentralized fashion. We discussed in detail, how message authentication could be achieved. There are several functions and protocols used for message authentication Message Authentication Mechanism classification: Message encryption MAC Hash Outlines of today’s lecture Digital signature and authentication protocols Problems in message authentication Different protocols for message authentication will be studied Digital Signature Standard (DSS) and Digital Signature Algorithm (DSA) will be explored Objectives You would be able to present an understanding of the higher level message authentication mechanism. You would be able demonstrate knowledge about different protocols used for message authentication Problem in message authentication Message authentication protect two parties from third party, will it protect two parties from each ?? John sends authenticated message to Marry (msg+MAC) Marry may forge a different message and claims that it comes from John John can deny sending the message to Marry later on hence include authentication function with additional capabilities Digital Signature Properties must depend on the message being signed must use information unique to sender to prevent both forgery and denial must be relatively easy to produce must be relatively easy to recognize & verify be computationally infeasible to forge with new message for existing digital signature with fraudulent digital signature for given message be practical save digital signature in storage Direct Digital Signatures Involve only sender & receiver Assumed receiver has sender’s public-key Digital signature made by sender signing entire message or hash with private-key can encrypt using receivers .