What do you need to establish computer security?

Lennart Jorelid

There are essentially four aspects of computer security:

Aspect Generally achieved by Explanation Effect
Confidentiality Encryption Protects message content from any but sender and recipient Transmission eavesdroppers cannot read or use the message content.
Integrity Message Digest Verifies that a message has not been modified since it was sent Transmission hijackers cannot modify message in transit
Authenticity Digital Signature + Password Uniquely identifies the sender of a message Verification of actual sender possible
Nonrepudiation Cryptographic Receipt Prevents a sender from falsely denying sending a message Message recipient can prove that a message was sent by sender

The first two aspects restrict unwanted interception or modification of a message in transit between a sender and a recipient. The last two aspects ensures that the identity of the sender can be pinpointed.