Cryptographic Attacks
Passive Attacks
Passive attacks are in the nature of eavesdropping on, or monitoring of, transmissions. The goal
of the opponent is to obtain information that is being transmitted. Passive
attacks are of two types:
Release of message contents: A telephone conversation, an e-mail message and a transferred file
may contain sensitive or confidential information. We would like to prevent the opponent from
learning the contents of these transmissions.
Traffic analysis: If we had encryption protection in place, an opponent might still be able to
observe the pattern of the message. The opponent could determine the location and identity of
communication hosts and could observe the frequency and length of messages being
exchanged. This information might be useful in guessing the nature of communication that was
taking place.
Passive attacks are very difficult to detect because they do not involve any alteration of data.
However, it is feasible to prevent the success of these attacks.
