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Introduction Cryptography
• The field of cryptology is generally divided into • It is the art and science of making a
the two mutually dependent fields cryptosystem that is capable of providing
Chapter 8 – cryptography and information security
– cryptanalysis • It deals with the actual securing of digital data
• Cryptography concerns the design of
Data Security and Integrity • It refers to the design of mechanisms based
(mathematical) schemes related to information
on mathematical algorithms that provide
security which resist cryptanalysis
fundamental information security services.
• cryptanalysis is the study of (mathematical)
techniques for attacking cryptographic schemes.
Cryptanalysis Encryption Authentication
• Cryptanalysis is the sister branch of • It is the way of identifying the authorized and
unauthorized personal from accessing of the data
cryptography and they both co-exist
• The requirement of Authentication
• It involves the study of cryptographic • Disclosure: Release of message contents to any
mechanism with the intention to break them person or process not possessing the appropriate
cryptographic key
• It is also used during the design of the new
• Masquerade: Insertion of messages into the
cryptographic techniques to test their security network from a fraudulent source
strengths. • Content modification: Changes to the contents of a
message, including insertion, deletion,
transposition, and modification.
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Firewalls Cont’d.. VPN
• Firewalls are intended to build a wall around your • Every message that is to be sent or received from • A virtual private network (VPN) allows remote
network and the attached servers and clients the network is processed by the firewall, which users to securely access a corporation’s local
• It refers to either hardware or software that determines if the message meets security
filters communication packets and prevents some guidelines established by the business
area network via the Internet, using a variety
packets from entering or exiting the network of VPN protocols.
based on a security policy • If it does, it is permitted to be distributed, and if
it doesn’t, the message is blocked • VPNs use both authentication and encryption
• The firewall controls traffic to and from servers
and clients • Firewalls can filter traffic based on packet to secure information from unauthorized
• forbidding communications from untrustworthy attributes such as persons
sources, and allowing other communications – source IP address
• Can provide confidentiality and integrity
– destination port or IP address
from trusted sources to proceed – type of service
Cont’d… Transport Layer Security (TLS) Cont’d…
• VPNs are traditionally used for: • It is a cryptographic protocol that is designed to • It is designed to be application protocol
• Intranets: Intranets connect an organization’s provide both security and data integrity for independent
locations. These locations range from the communications over a reliable transport
headquarters offices, to branch offices, to a protocol such as (TCP) • TLS protocol consists of two main
remote employee’s home. components:
• It allows client-server applications to
• Often this connectivity is used for e-mail and for communicate across a public network – Handshake protocol, to set session states and
sharing applications and files.
• Remote Access: Remote access enables • preventing eavesdropping, tampering, and – shared private keys, and Record protocol, to
telecommuters and mobile workers to access e- message forgery transmit data securely using the shared keys.
mail and business applications • provide end-point authentication and
• Extranets: Extranets are secure connections confidentiality over the Internet.
between two or more organizations.
