Message Integrity Protocols
Written by Vyga V R Sunday, 28 March 2010 08:33
Encryption protects against passive attack. A different technique is to protect against active attack which is falsification of data and transactions. Protection against such attacks is known as message authentication and the protocols used to implement message authentication is known as message integrity protocols.
Message authentication.
A message, file, document or other collection of data is said to be authentic when it is genuine and came from its alleged source. Message authentication is a procedure that allows communicating parties to verify that received messages are authentic. The two important aspects are to verify that the contents of the message have not been altered and that the source is authentic. It will be an added advantage if we are able to trace out the sequence number of a particular message relative to other messages flowing between two communicating parties.
Authentication Using Symmetric Encryption.
It is possible to perform authentication simply by the use of symmetric encryption. If we assume that only the sender and receiver share a key, then only the genuine sender would be able to successfully encrypt a message for the other participant. Also, if the message includes an error-detection code and a sequence number, the receiver is assured that no changes have been made and that sequencing is proper. If the message also includes a time stamp, the receiver is assured that the message has not been delayed.
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