This document discusses network security and cryptography. It begins by defining a network and some common network threats. It then discusses network security goals like avoiding denial of service attacks. The document outlines different cryptography techniques like symmetric and asymmetric key cryptography. Symmetric cryptography uses a shared key while asymmetric uses public and private keys. Specific algorithms like RSA and DES are described. The document proposes combining numerals and alphabets in encryption to increase security. It concludes cryptography can securely hide and transmit data through encryption and decryption.
1. NETWORK SECURITY
CRYPTOGRAPHY
Presented BY
Sankari.P(B.Sc[CS] S/F)
Sadakathullah Appa College
Tirunelveli -11.
Guided by:
Mrs.J .Jannathul Firthous ,M.sc,M.phil
2. WHAT IS NETWORK
A network is an interconnection
or a media between two or more
systems to share information
among them.
The various threats caused to
network are :
Remote Login
Application Backdoors
SMTP Session Hijackings
Operating System Bugs
Spams
Viruses etc.
3. NETWORK SECURITY
The security provided to the network
is called network security which at
present is looming on horizon as a
massive problem.
There are two kinds of Network
Security mainly as :
Transit Security: It just encrypts
the packets to be transferred.
Traffic Security : It acts just as a
screen between hosts & remote
sites.
5. OBJECTIVE OF SECURITY
To avoid data threats
To avoid denial of services
To secure our data from masquerades
To safeguard our data’s from traffic analyzer
To not to make massage for the third person available
6. PASSWORD AUDITING
Should not be in uppercase
Must have at least 8 characters
Must include alphabets, numeric keys & special
characters
Password should not be the name of the user,
dictionary word etc.,
It must be updated at least once a month
7. DATA SECURITY
To monitor the user’s ACCESS
CONTROLS
System that are connected in network must be protected
with firewalls
To protect the integrity & availability of the institution’s
information asset’s
8. PROBLEMS & ATTACKS
There are few intertwined areas in network security as:
Secrecy
Authentication
Non-Repudiation
Integrity Control etc.
The threats are classified into two categories :
Passive Attacks :
A passive attack is one in which the attacker eavesdrops and
listens to the message but can’t modify the message.
Active Attacks :
An active attack is one in which the attacker modifies, deletes,
replay or introduce new messages into the stream of message.
11. CRYPTOGRAPHY
It is derived from the Greek word that meant for secret writing.
Cryptography is a Software or Hardware programs
use Mathematical Functions , Formulas(Algorithms) to
change text from one form to another.
Cryptography is the science and art of transforming messages to
make them secure and immune to attacks.
It provides Confidentiality, Integrity, Accuracy.
Applications of cryptography includes ATM cards, computer
passwords, and electronic commerce.
It’s very useful to our Army & Police network to transfer
confidential data
12. TECHNIQUES
The data is transferred by applying two techniques
1.Encryption
2.Decryption
Encryption :The way of converting the plain text to the
cipher text by the means of few keys is called as the
“Encryption”.
Decryption :The way of converting the cipher text to
the plain text by the use of keys that are suitable to it is
called as “Decryption”.
15. SYMMETRIC KEY CRYPTOGRAPHY
The implementation of a simple cryptography using
single key is done by the secret-key algorithms.
Also known as SECRET KEY CRYPTOGRAPHY .
Sender & Receiver uses same key and an Encryption /
Decryption Algorithm to Encrypt / Decrypt data .
(i.e ) The Key is Shared
This can be done by p-box, s-box and product cipher
18. SUBSTITUTION CIPHER
Replacing of each letter or
group of letters of plain text
into cipher text by another
letters is called as
“Substitution cipher”.
The substitution may be :
Monoalphabetic Substitution
Polyalphabetic Substitution
19. TRANSPOSITION CIPHER
The change offered in
the position of the text
i.e. By jumbling the
words is called as
“Transposition cipher”.
And the technique used
here is termed as “Mass
Technique”.
20. ASYMMETRIC KEY CRYPTOGRAPHY
Also known as PUBLIC KEY CRYPTOGRAPHY . Sender &
Receiver uses different keys for Encryption & Decryption
namely PUBLIC & PRIVATE respectively
Public key algorithms are formed when it satisfies the
following requirements:
o D(E(P))=P.
o Difficulty to deduce D from E.
o E cannot be broken by a chosen plain text attack.
D -> Deciphering E -> Enciphering
22. RSA ALGORITHM
RSA is derived from the names of the 3 discoverers
named Rivest, Shamir, Adleman.
The RSA algorithm is one of the widely used in the key
algorithms.
(1)The main function of this algorithm is providing
approach to public key cryptography & Encryption
(2) In this the CIPHER TEXT are the integer’s
between 0 to n-1
C =e M mod n m->message ,e->encryption
M=d C mod n C->cipher text ,d->decryption
=(e M) d mod n n-> integer’s (r*a) r & a are prime
=m e d mod n number’s
23.
24. Symmetric key
cryptography
• Only 1 shared key is involved.
• The same key encrypts and
decrypts the plaintext.
• The shared key is kept secret
between Alice and Bob.
• Examples of Symmetric
algorithms:
– DES, 3DES, AES, IDEA,
BLOWFISH, TWOFISH, RC4,
RC5, SAFER etc.
Asymmetric key
cryptography
• Here 2 keys : a private and a
public key are involved.
• The Public key encrypts the
plaintext while the private key
decrypts it.
• The private key is just kept
secret by the Bob while the
public key is made public.
• Examples of Asymmetric
algorithms:
– Diffie-Hellman, RSA, El Gamal,
Elliptic Curve Cryptography
(ECC) etc.
25. APPLICATIONS
• Defense Services
• Secure Data Manipulation
• E – Commerce
• Business Transactions
• Internet Payment Systems
• User Identification Systems
• Access Control
• Data Security
26. PROPOSED CONCEPT
As known the data has been easily hacked
even for the 52- bit encryption too. So, the
encryption bits of 52-bits should be given
with the combination of both numerals and
alphabets ( for example one alphabet is
placed for 13-bits each).
The placement of alphabet is known only to
the particular sender & receiver such that it
secures the data to be sent.
27. CONLUSION
This paper describes a technique to successfully
hiding and secure the data or massage with the
help of Encryption or Decryption technique with
the Cryptography And Network Security.
However ,this research work & software package
provide a good starting point for anyone
interested in learning about Cryptography.
28. “For every lock there is a key………
It is better to keep safe your lock than the key”