Telecommunication, Internet, and E-Commerce

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Telecommunication, Internet, and E-Commerce
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Communication hardware

• Communication channel
• Communication devices

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Communication Channel Media

• Wire cables
• twisted-pair (voiceband) 2MBPS
• coaxial 550 MBPS
• fiber-optic 30 GBPS
• Wireless channel
• microwave (land-based, satellite-based)100 MBPS
• infrared 4 MBPS

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Communication Channel Characteristics

• Data rate bps, bandwidth (higher bandwidth
  means more data can be transmitted)
• Transmission method
• Asynchronous one character is sent at a time.
• Start bit Character code Parity bit Stop
  bit
• Synchronous the codes for several hundred
  characters are sent together in a block.
• Start bytes Codes for many characters Error
  checking bits Stop bytes

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Communication Devices

• Modem
• ISDN adapter
• Network Interface Card
• Routerdevice that connects two networks
• Communication control units
• multiplexer allows a single channel to carry
  simultaneous data transmission from many
  terminals.
• front-end processor a dedicated computer to
  perform communication functions.

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Network Organization

• Star network polling
• Bus network contention
• Ring network token
• Local Area Network/Wide Area Network
• peer-to-peer all PCs are equal
• client/server network
• Client-Server Computing

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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).

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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 and Domain Name Service

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Major Internet Services

• Email
• FTP - File Transfer
• Web browsing and publishing
• Telnet

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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 pageHypertext/Hypermedia
• a document that contains hyperlink (link) to
  another hypertext.
• Uniform Resource Locator (URL)
• http//Web site/Directory/Document

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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

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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 companys different locations, or establish
  extranet links between business partners.
• Improved communications between business partners

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E-Commerce

• Buying and selling, and marketing and servicing
  of products and services, and information via
  computer networks.

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E-Commerce Models

• 1. Storefront model b2c
• Shopping cart, on-line shopping mall
• 2. Auction model e-Bay
• 3. Portal model yahoo.com
• 4. Dynamic pricing name-your-price,
  comparison-pricing, bartering(exchange items),
• 5. B2B EDI (Electronic Data Interchange)
• 6. Etc.

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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?

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Encryption (Cryptography)

• Plain text the original message in
  human-readable form.
• Ciphertextthe encrypted message
• Encryption algorithm the mathematical formula
  used to encrypt the plain text.
• Key the secret key used to encrypt and decrypt a
  message.

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Encryption Algorithms

• Private key encryption
• Public key encryption
• Digital signature
• Digital certificate

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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

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Public Key Encryption

• Uses two different keys a public and a private
  key.
• Receivers public key must be delivered in
  advance.
• Sender uses receivers 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.

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Ceritificate

• A certificate is an identification issued by a
  trusted third-party certificate authority (CA).
• A certificate contains records such as a serial
  number, users name, owners public key, name of
  CA, etc.
• Example of CA VeriSign, U.S. Postal Service.

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Cookies

• Designed to hold information about a user.
• Created by a web site and saved on the visitors
  machine.
• It contains
• Web site that sets the cookie.
• One or more pieces of data.
• Expiration date for this cookie.
• Cookies directory
• Windows C\windows\cookies
• Netscape c\program files\Netscape\users\
• Browser sends cookie with the URL when you visit
  the site that issued the cookie.