• Table of Contents

Overview of Cryptography

In an ideal world, seamless communication flows between hosts, ensuring the smooth exchange of information.

Figure 1.1 Normal flow.

In developing a particular security mechanism or algorithm, one must always consider potential attacks on those security feature.

Security Issues in Networking

Security attacks can be classified in terms of passive and active attacks.

• Passive attacks are in the nature of eavesdropping on, or monitoring of, with the goal of obtaining information that is being transmitted.
• Active attacks involve unauthorized attempts to alter, destroy, or disrupt data or system operations.

Interception and modification are what can be described as passive and active attacks, respectively.

1. Interception: An unauthorized party gains access to an asset. An attack on confidentiality

   

2. Modification: An unauthorized party not only gains access to but tampers with an asset. This is an attack on the integrity.

   

While passive attacks are difficult detect, there are measure available to prevent their success. On the other hand, active attacks are quite difficult to prevent and so the goal is to detect active attacks and to recover from any disruptions or delays caused by them.

Security Services

In addressing the complexities of network security, the focus revolves around three key aspects:

• Data Accessibility: Ensuring contents are accessible to authorized parties.
• Data Integrity: Ensuring contents remain unchanged during transmission.
• Data Confidentiality: Preventing unauthorized revelation of contents.

Security Mechanism