Cryptography & Network Security
The cryptography is the study of the encryption principle method. It is
an very interesting subject because it explains all the encrypting and the
decripting method that are in the current use.
The cryptography is arrived from the GREEK word KRYPTOS, where the
meaning is the hidden secrets. This subject is used to practice the study
of secure Mechanism.
The Need for Security:
• Provide a user id and
password to every user and use that information to authentication to user.
• Encode the information
stored in the databases. So that it is not visible to users who do not have the
right permissions.
Basic Terminology:
• plaintext - the original message
• cipher text - the coded message
• cipher - algorithm for transforming plaintext to cipher text
• key - info used in cipher known only to sender/receiver
• encipher (encrypt) - converting plaintext to cipher text
• decipher (decrypt) - recovering cipher text from plaintext
• cryptography - study of encryption principles/methods
• cryptanalysis (code breaking) - the study of principles/ methods of deciphering cipher text without knowing key
• cryptology - the field of both cryptography and cryptanalysis
Service and Mechanism:
• The International
Telecommunication Union-Telecommunication Standardization Sector : provides some security services and some
mechanism to implement some services.
1)
Data confidentiality
2)
Data integrity
3)
Authentication
4)
No repudiation
5)
Access control
Types of Attacks :
1)
Criminal attack
2)
Publicity attack
3)
Legal attack
Criminal attack:
Fraud (ATM , CC) ,Brand Theft or the Identity Theft(Password Theft).
Publicity attack:
Attack is to damage the website.
Legal attack:
Attacker tries to convince the judge & come out.
