Cryptography - Computer Network Security

Computer network security problems can generally be divided into four interrelated categories.

 

1.  Secrecy/Confidentiality

The information sent through computer networks must be maintained in such a way that confidentiality can not be known by unauthorized parties know the information.

2. Authentication

Identification of the parties are communicating via the network must be done. Parties who communicate via the network should ensure that other parties are invited to communicate is actually the desired party.

3.  Nonrepudiation

Proof of correspondence between the parties submit any information with the information submitted will also need to be in communication through computer networks. With such evidence, the identity of the sender of information can be ascertained and the denial of such party for the information that has been sent can not be done.

4. Integrity Control

The information received by the receiving party shall be equal to the information that has been sent by the sender. Information that has changed in the process of sending, for example modified by other parties, should be known by the receiving party.

In the protocol stack OSI (Open Systems Inteconnection) Reference Model, there are several possible placement of the network security aspects. There is also a possibility that the security aspects of the network is not only placed on one layer, but combined on multiple layers at once because the placement of each layer has the advantages of each.

At the physical layer, transmission cables can be secured with the use of tube coating containing high pressure gas. At the data link layer, packet on the path to point-to-point can be encrypted when leaving a machine and decrypted when it went into another machine. At the network layer, the use of firewalls and IPsec protocol used to ensure security. At the transport layer, the connection can be encrypted to ensure the safety of inter-process (end-to-end). Finally, the application layer, authentication and nonrepudiation aspects can be secured by the algorithm used in applications.