MODULE 3 Message Authentication MAC Hash Functions

MODULE 3

Message Authentication
MAC
Hash Functions

, Message Authentication
• Message authentication is a mechanism or
service used to verify the integrity of a
message.
• Message authentication assures that data
received are exactly as sent (i.e., contain no
modification, insertion, deletion, or replay).

, Message Authentication
• message authentication is concerned with:
– protecting the integrity of a message
– validating identity of originator
– non-repudiation of origin (dispute resolution)
• Some sort of function that produces an
authenticator : a value used to authenticate a
message. Higher level authentication protocol
• Three alternative functions used:
– message encryption
– message authentication code (MAC)
– hash function

, Security Requirements
• disclosure
• traffic analysis
• masquerade
• content modification
• sequence modification
• timing modification
• source repudiation
• destination repudiation