Cryptography and Network Security_Chapter 1.ppt

R.SHANTHI PRABHA M.Sc., M.Phil.,
ASSISTANT PROFESSOR
DEPARTMENT OF COMPUTER SCIENCE
SACWC, CUMBUM

 Information Security requirements have changed in recent
times
 traditionally provided by physical and administrative
mechanisms
 computer use requires automated tools to protect files and
other stored information
 use of networks and communications links requires
measures to protect data during transmission

 Computer Security - generic name for the
collection of tools designed to protect data and
to thwart hackers
 Network Security - measures to protect data
during their transmission
 Internet Security - measures to protect data
during their transmission over a collection of
interconnected networks

 our focus is on Internet Security
 which consists of measures to deter, prevent,
detect, and correct security violations that
involve the transmission & storage of information

 ITU-T X.800 “Security Architecture for OSI”
 defines a systematic way of defining and providing
security requirements
 for us it provides a useful, if abstract, overview of
concepts we will study

 consider 3 aspects of information security:
 security attack
 security mechanism
 security service

 any action that compromises the security of information
owned by an organization
 information security is about how to prevent attacks, or
failing that, to detect attacks on information-based
systems
 often threat & attack used to mean same thing
 have a wide range of attacks
 can focus of generic types of attacks
 passive
 active

 enhance security of data processing systems and
information transfers of an organization
 intended to counter security attacks
 using one or more security mechanisms
 often replicates functions normally associated with
physical documents
 which, for example, have signatures, dates; need protection
from disclosure, tampering, or destruction; be notarized or
witnessed; be recorded or licensed

 X.800:
“a service provided by a protocol layer of communicating
open systems, which ensures adequate security of the
systems or of data transfers”
 RFC 2828:
“a processing or communication service provided by a
system to give a specific kind of protection to system
resources”

 Authentication - assurance that the
communicating entity is the one claimed
 Access Control - prevention of the unauthorized
use of a resource
 Data Confidentiality –protection of data from
unauthorized disclosure
 Data Integrity - assurance that data received is
as sent by an authorized entity
 Non-Repudiation - protection against denial by
one of the parties in a communication

 feature designed to detect, prevent, or recover
from a security attack
 no single mechanism that will support all
services required
 however one particular element underlies many
of the security mechanisms in use:
 cryptographic techniques
 hence our focus on this topic

specific security mechanisms:
 encipherment, digital signatures, access controls, data
integrity, authentication exchange, traffic padding,
routing control, notarization
pervasive security mechanisms:
 trusted functionality, security labels, event detection,
security audit trails, security recovery

 using this model requires us to:
1. design a suitable algorithm for the security
transformation
2. generate the secret information (keys) used
by the algorithm
3. develop methods to distribute and share the
secret information
4. specify a protocol enabling the principals to
use the transformation and secret
information for a security service

 using this model requires us to:
1. select appropriate gatekeeper functions to
identify users
2. implement security controls to ensure only
authorised users access designated
information or resources
 trusted computer systems may be useful to
help implement this model

 have considered:
 definitions for:
 computer, network, internet security
 X.800 standard
 security attacks, services, mechanisms
 models for network (access) security

Cryptography and Network Security_Chapter 1.ppt

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Cryptography and Network Security_Chapter 1.ppt