Computer Security
Internet Security
Physical Security

Computer Security

Computer Security

Computer Security
• It refers to protection of a computer and
the information stored in it, from the
unauthorised users.

Computer Security
• It refers to protection of a computer and the
information stored in it, from the
unauthorised users.
• Computer security is a branch of computer
technology known as information security as
applied to computers and networks.

Security Threats

Security Threats
1 Malicious Code and Software
2 Hackers and Crackers

Malicious Code and Software

Malicious Code and Software
• It is a software program that generates
threats to the computers and data stored
on it.

Malicious Code and Software
• It is a software program that generates
threats to the computers and data stored
on it.
• This code can be in the form of worms
,logic bombs, viruses, Trojan horses and
other type of software.

Malicious Code and Software

Hackers and Crackers

Hackers and Cracker

Hackers and Cracker

Hackers and Cracker
• A hacker is a person who breaks into
computers without authorisation. He is
actively involved in computer security and
are non professional or programmers
without formal training.

Malicious Program

Malicious Program
• Any computer program or code that is
designed to do harm, can be termed a
malicious program. Ex
– Virus , Worms , Trojan horse , Logic bomb
, Spyware etc.

Virus

Virus
• It is a computer program that can copy
itself and infect a computer without the
permission or knowledge of the owner. Virus
has the ability to infect different parts of
the computer.

Worms

Worms

Worms
• A computer worm is a self-replicating
computer designed to destroy data. Worm
program often use network connections to
spread from one computer to another
computer system. Thus, worms attack
systems that are linked through
communication lines.

Logic Bomb

Logic Bomb

Logic Bomb
• This is one of the oldest types of programs
and it embeds its code into legitimate
programs. Like a bomb it explodes all the
data when certain conditions are met. This
could be either destroying or deletion of
certain files on a particular time, and so on.
It reacts as a time bomb.

Trojan Horses

Trojan Horses

Trojan Horses

Trojan Horses
• Trojan appears to perform a desirable
function but in fact, performs undisclosed,
malicious function. These programs enter
into a computer through an e-mail or free
programs that are download from the
internet.

Trojan Horses
• Trojan appears to perform a desirable
function but in fact, performs undisclosed,
malicious function. These programs enter
into a computer through an e-mail or free
programs that are download from the
internet.
• Once they safely pass into the computer,
they may lie inactive from months before
they activated or complete control of the
computer is given to a hacker.

• It allows unauthorised access to the host
machine, giving them ability to save their
files on the user’s computer or even to
watch the user’s screen and to control
the computer.

Antivirus

Antivirus
• It is a software utility which mainly
prevents and removes computer viruses,
including worms and Trojan horses. It scan
the hard disk for viruses and tries to
removes them, if found.

Antivirus

Antivirus Protection

Security techniques from hacker
and crackers

Security techniques from hacker
and crackers
• Cryptography
• Captcha

Cryptography

Cryptography
• Cryptography is the process of alternating
the original massages to hide their meaning
from opponents who might intercept them.

Cryptography
• Cryptography is the process of alternating
the original massages to hide their meaning
from opponents who might intercept them.
• Cryptography relies upon to basic
components an algorithm and key.
• Some of the algorithm are given here.
1 Secret Key Cryptography
2 Public Key cryptography
3 Hash Function
4 Digital Signature

Secret Key Cryptography

Secret Key Cryptography
• A single key is used in SKC for both
encryption and decryption of data. In this
form of cryptography the key must be
known the sender and receiver.

Public Key Cryptography

Public Key Cryptography
• Each person in this techniques gets known
as the public and private key. Each person’s
public key is publicly known and private key
kept secret.
• The sender uses the receiver’s public key to
encrypt the message and when receiver
receives the encrypted massage , he uses
his private key to decrypt the massage.

Hash Function

Hash function
• It is also called massage digests and it is a
one way encryption algorithm that does not
use any key to encrypt or decrypt the
massage.
• It uses a digital fingerprint of a file’s
contents, in order to ensure that the file
has not been changed by an intruder or any
type of virus.

Digital Signature

Digital Signature
• Digital signature uses the public key
cryptography technique. It uses two
different keys in an algorithm but these are
mathematically related to each other. One
is for digital signature creation and another
key for verifying a digital signature.

Captcha
• It’s full name is “Completely Automated
Public Turing test to tell Computers and
Humans Apart”.
• In modern computers, a robot or an
automated program generates undesired
information in the web pages and websites.
• A Captcha is a type of test in computing to
make sure that the response is not
generated by a computer.
• A Captcha is a program that generates

Internet Security

Internet Security
• Internet Security is a branch of
information technology known
as information security as applied
to computers and networks.

OSI Reference Model
• Its full name is Open System
Interconnection.
• The International Standards Organization
developed in the early 1980 to promote
interoperability of network devices.
• It has seven layer.

Seven layer of OSI model
• Application Layer
• Presentation Layer
• Session Layer
• Transport Layer
• Network Layer
• Data Link Layer
• Physical Layer

Security for the OSI Model

Security for the OSI Model
• Authentication
• Access Control
• Logging and Monitoring
• Data Integrity
• Data Confidentiality

TCP/IP Reference Model

TCP/IP Reference Model
• TCP/IP is based a four layer reference
model.
• It is proposed by ISO(International Standards
Organization).
• Layers of TCP/IP model
Application Layer
Transport Layer
Internet Layer
Network Interface layer

Security for TCP/IP Model

Security for TCP/IP Model
• Routers :- A router is a network traffic
management device designed to forward
the packets. It consists of hardware and
software to implement the task for
forwarding the packets.
• Firewall :- Firewall is a system has been
designed to prevent the unauthorized
access to or from a private network.

Physical Security

Physical Security
• The connection between physical system
and logical systems ensure that, in order to
protect logical systems, the hardware which
is alive at that time must be physically
secured.
• It involves protecting sites from natural and
man-made physical threats.

Physical Security Threats

Physical Security Threats
• Weather : floods, fire, snow, ice, heat, cold
• Earth movement : earthquakes, mudslides
• Structural Failure : building collapse
• Fire/chemical : explosions, smoke
• Energy : loss of power, radiation, magnetic
wave infrastructure
• Biological : virus, infections of animal and
insects

Educating Personal
• An organization can educate its staff
members on the importance of their
physical security through the use of self-
paced or formal instructions, security
education bulletins , posters, training films
and tape or awareness data that drive home
the importance of constant vigilence.

Administrative Access Control
• This is an important category of physical
access control. It addresses the procedural
application of physical controls. There exist
different type of physical control devices
that make a site more secure.

Physical Security Controls
• This is the next category of the physical
access control which includes mechanical
and electronic access controls such as
gates, doors, keys and combination locks.
By physical security, most people
understand these types of access control
because these devices are the least
complicated and expensive.

Technical Controls
• The next category of physical security
control is the use of computer hardware and
software. Some of the technical security
measures are discussed here. A smart card,
which is similar to regular payment card,
access card, the smart card has many
purpose, such as medical identification,
travel ticketing identifiction and builiding
access control.

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