What do you need to establish computer security?
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.