Telecommunication, Internet, and E-Commerce. Communication Channel Media Bandwidth: The speed at which information is transmitted over a communication.

Telecommunication, Internet, and

E-Commerce

Communication Channel Media

• Bandwidth: The speed at which information is transmitted over a communication medium. It is measured by the bits of data transmitted per second.

• Wire cables: – twisted-pair (voiceband): 2MBPS– coaxial: > 100 MBPS

• Broadband cable

– fiber-optic: 30 GBPS

– Broadband over Power Lines (BPL) • Wireless channel:

– microwave (land-based, satellite-based):100 MBPS– Satellite– infrared: 4 MBPS

Digital Subscriber Line (DSL)

• DSL offers high-speed data access over the single pair of the ordinary copper lines used with basic telephone service.– The Last Mile:

• The last mile is the final leg of delivering connectivity from a communications provider to a customer.

Types of Networks

• Local Area Network– Within office– Cable or Wireless– peer-to-peer: all PCs are equal– client/server network

• Wireless local area network (WLAN)• Metropolitan Area Network

– City area– Fiber optic cable

• Wide Area Network

Wireless local area network (WLAN)

• WI-FI: Wireless local area network (WLAN) based on the IEEE802.11 specifications.

• Hotspot: A person with a Wi-Fi device, such as a computer, cell telephone, or personal digital assistant (PDA) can connect to the Internet when in proximity of an Access Point. The region covered by one or several access points is called a hotspot.

Introduction to Internet

• A network of networks that connects computers across the world.

• It is growing rapidly:– Host computers– Users– Information

• It is a network that follows the TCP/IP protocol (packet switch network).

Internet protocol

– Transmission Control Protocol – handles communications between applications.

• A message is divided into pieces called packets.

• Packets are numbered and may be transmitted by different routes.

– Internet Protocol – handles communications between network addresses.

• A computer on the internet is assigned an unique address, IP address, which consists of 4 numbers (each number is less than 256) separated by period. Exanple, 158.104.1.10

Domain Name System

• Domain:– .com, .net, .org, ..edu, .int, .gov– .info, .biz, .name, .etc.

• Domain names are the familiar, easy-to-remember names for computers on the Internet.– Yahoo.com

• Each domain name correlates to assigned IP address:– Yahoo.com – 66.218.71.102

Organizations that Regulate Internet

• ICANN (Internet Corporation for Assigned Names and Numbers):have responsibilities in Internet Protocol addresses and domain names.

• Domain name registry

Examples of Internet Services

• World Wide Web:– A system of interlinked, hypertext documents

that runs over the Internet. – Web publishing and browsing

• Email• FTP - File Transfer• Telnet

World Wide Web

• A service on the Internet that links information so that the user can easily go from one piece of information to another, related piece.

• Web page:Hypertext/Hypermedia– a document that contains hyperlink (link) to

another hypertext.

• Uniform Resource Locator (URL):– http://Web site/Directory/Document

Intranet

• It is a corporate network that functions with Internet technologies, such as browsers, using Internet protocols.

• Major applications:– Corporate/department/individual web pages– Database access– Interactive communication– Document distribution

Applications of Intranets

Communicate andCollaborate with

E-mail, chat, conf.

Communication and Collaboration

Secure, universal access. To viewcorporate data

Author, publish andshare hypermedia

documents

Centrally administerclients, servers,

security, and traffic

Business Operations and Management

Web Publishing

Intranet Portal Management

FIREWALL

FIREWALL

Internet

Extranet

Customers,Suppliers

EnterprisePortal

Existing E-MailVoice MailSystems

Existing Database and Enterprise appl.

HTML, MS OfficeXML, Java

Existing Hardwareand Networks

Extranet

• It is a network that links the intranets of business partners over the Internet by Virtual Private Network.

• Virtual Private Network:– A secure network that uses the Internet as its main

backbone network to connect the intranets of a company’s different locations, or establish extranet links between business partners.

• Improved communications between business partners

E-Commerce• Buying and selling, and marketing and

servicing of products and services, and information via computer networks.

E-Commerce Models• B2C: Storefront model

– E-tailing (electronic retailing)– Shopping cart, on-line shopping mall

• B2B: – Electronic Data Interchange (EDI)– Electronic Exchange: An electronic forum where manufacturers,

suppliers, and competitors buy and sell goods.• Example: WorldWide Retail Exchange (WWRE)

• C2C:– Auction model: e-Bay

• Moble Commerce (M-commerce)– Wireless Application Protocol (WAP)– PDA, Cell phone,

Electronic Payment Systems

• Authentication technologies

• Digital certificate

• Electronic cash

• Electronic wallet:contains – electronic cash or credit card info– Owner identification

• Credit/debit/smart card

Internet Security

• Authenticity: Is the sender of a message who they claim to be?

• Privacy: Are the contents of a message secret and only known to the sender and receiver?

• Integrity: Have the contents of a message been modified during transmission?

• Nonrepudiation: Can the sender of a message deny that they actually sent the message?

Encryption (Cryptography)

• Plain text: the original message in human-readable form.

• Ciphertext:the encrypted message

• Encryption algorithm: the mathematical formula used to encrypt the plain text.

• Key: the secret key used to encrypt and decrypt a message.

Encryption Example

• Digits: 0-9, • Encryptor:

– Replace each digit by Mod(Digit + Key, 10)• Key’s value is from 0 to 9

– If Key = 7, then:• 0 -> 7, 1->8, 2->9, 3->0, 4->1, 5->2

• Decryptor:– Replace ach digit byMod(Digit + (10-Key), 10)– If key=7, then

• 7->0, 8->1, 9->2, 0->3

Encryption Algorithms

• Private key encryption

• Public key encryption

• Digital signature

• Digital certificate

Private Key Encryption

• The same key is used by a sender (for encryption) and a receiver (for decryption)

• The key must be transmitted to the receiver.

• Example: – DES (Data Encryption Standard) algorithm

with 64-bit key

Public Key Encryption• Uses two different keys: a public and a private key.• Receiver’s public key must be delivered in advance.• Sender uses receiver’s public key to encrypt the message and

receiver uses private key to decrypt the message (Sender can be sure the receiver is the true receiver)

• Example:– RSA (Rivest, Shamir, and Adelman) algorithm with 512-bit to 1024-bit

key.

• Note: Although the two keys are mathematically related, deriving one from the other is “computationally infeasible”.

Digital Signature

• It is used for the authentication and nonrepudiation of senders by applying public key encryption in reverse.

• To make a digital signature, a sender encrypts a message with his/her private key, and any receivers with sender’s public key can read it.

Ceritificate

• A certificate is an identification issued by a trusted third-party certificate authority (CA).

• A certificate contains records such as a serial number, user’s name, owner’s public key, name of CA, etc.

• Example of CA: VeriSign, U.S. Postal Service.

Transaction Certificate

• A transaction certificate attests to some fact about the conduct of a transaction that can be used to prevent repudiation.

• SSL (Secure Socket Layer) Protocol developed by Netscape.

• SET (Secure Electronic Transaction) Protocol developed by Visa and MasterCard.

Cookies• Designed to hold information about a user.• Created by a web site and saved on the

visitor’s machine.• It contains:

– Web site that sets the cookie.– One or more pieces of data.– Expiration date for this cookie.

• Cookies directory:• Browser sends cookie with the URL when

you visit the site that issued the cookie.