Cryptography is the art and science of achieving security by encoding messages to make them non-readable.
Cryptanalysis is the technique of decoding messages from a non-readable format back to readable format without knowing how they were initially converted from readable format to non-readable format.
Cryptology is a combination of cryptography and cryptanalysis.
Principles of Security:-
1)Confidentiality
2)Integrity
3)Authentication
4)Access control
5)Availability
6)Non-repudiation
7)Ethical and legal issues
Types of attacks:-
1)General attacks-Criminal attacks,publicity attacks,legal attacks
2)Technical view-a)Theoretical concepts-
I)Passive attacks-i)release of message contents ii)traffic analysis
II)Active attacks-i)Interception,ii)Fabrication,iii)Modification,iv)Interruption
3)Program attack-
a)Virus- A virus is a computer program that attaches itself to another legitimate program and causes damage to the computer system or to the network.
During lifetime ,a virus goes through four phases:-
Dormant phase,Propagation phase,Triggering phase ,Execution phase.
b)Worm
A worm does not perform any destructive actions and instead ,only consumes system resources to bring it down.
c)Trojan Horse
It allows an attacker to obtain some confidential information about a computer or a network.
d)Specific attacks-
Sniffing and spoofing-cause packet level attacks.
Phishing-It is new attack which attempts to fool legitimate users to provide their confidential information to fake sites
Pharming /DNS spoofing -attack involves changing the DNS entries so that users are redirected to an invalid site,while they thinking that they have connected to the right site.
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