Chapter 13: Electronic Commerce and Information...
Transcript of Chapter 13: Electronic Commerce and Information...
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Chapter 13: Electronic
Commerce and Information
Security
Invitation to Computer Science,
C++ Version, Third Edition
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Invitation to Computer Science, C++ Version, Third Edition 2
Objectives
In this chapter, you will learn about:
� E-commerce
� Databases
� Information security
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Invitation to Computer Science, C++ Version, Third Edition 3
Introduction
� E-commerce: financial transactions conducted
by electronic means
� Early days (early and mid-1990s) of online
commerce
� A customer fills out an order via the Web and
submits it
� The online order is printed out by the business, and then processed like a “traditional” purchase
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Introduction (continued)
� E-business
� Every part of a financial transaction is handled electronically, including
� Processing of orders
� Verification of credit
� Completion of transactions
� Issuing debits
� Alerting shipping
� Reducing inventory
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E-commerce
� Opening an online store requires at least as
much planning as building another physical
store location
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The Vision Thing
� In planning for opening an online store, a
company must access:
� Its objectives
� Risks involved
� Costs involved
� The company should go ahead with its plans
only if it is determined that its overall bottom line
will improve by going online
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Decisions, Decisions
� Personnel
� In-house development or outsourcing
� Hardware
� Web server machine
� Additional computers
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Decisions, Decisions (continued)
� Software: programs to
� Process customer orders
� Interact with accounting, shipping, and inventory control software
� Manage and store customer information
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Anatomy of a Transaction
� Goals for an online business
� Draw potential customers to your site
� Keep them there
� Set up optimum conditions for them to complete a purchase
� A typical online transaction can be divided into
nine steps
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Step 1: Getting There
� How can you get customers to your Web site?
� Conventional advertising
� Obvious domain name
� Search engine
� Portal
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Step 2: Do I Know You?
� Providing Web site personalization by:
� Asking the user to register and then log-in on
each visit
� Using cookies
� Providing incentives and benefits for return
customers
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Step 3: Committing to an Online
Purchase
� Must provide security for transmitting sensitive
information
� Encryption: encoding data to be transmitted into a
scrambled form using a scheme agreed upon between the sender and the receiver
� Authentication: verifying the identify of the
receiver of your message
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Step 3: Committing to an Online
Purchase (continued)
� SSL (secure sockets layer)
� A series of protocols that allow a client and a Web
server to:
� Agree on encryption methods
� Exchange security keys
� Authenticate the identity of each party
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Steps 4 and 5: Payment Processing
� Most common payment option: credit card
� Option 1
� Step 4: Online order form communicates with the accounting system
� Step 5: Accounting system verifies the customer’s credit and process the transaction on the fly
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Steps 4 and 5: Payment Processing
(continued)
� Option 2
� Step 4: Collect information on the customer’s
order
� Step 5: Evaluate the customer’s credit and complete the transaction offline
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Steps 6–9: Order Fulfillment
� Step 6: Order entry system alerts inventory
system to reduce the items in stock
� Step 7: Order entry system contacts shipping
system to arrange for shipping
� Steps 8 and 9: Shipping system works with the
shipping company to pick up and deliver the
purchase to the customer
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Figure 13.1: A Typical Online Transaction in Nine Steps
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Designing Your Web Site
� Web site taxonomy
� How information will be classified and organized on the Web site
� CRM (customer relationship management)
� Goals
� Improve your customer satisfaction
� Build customer relationships
� Bring people back to your Web site time and time
again
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Designing Your Web Site (continued)
� Some important Web site components
� Site map
� Navigation bar
� Shopping carts
� Order checkout forms
� Shipping options
� E-mail confirmations
� Privacy policy
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Designing Your Web Site (continued)
� Web pages should be designed to be displayed
on different machines, operating systems, and
browsers
� Text-only options should be offered for users
with slow connections, the visually impaired, and
the hearing-impaired
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Databases
� An electronic database
� Stores data items
� Data items can be extracted
� Data items can be sorted
� Data items can be manipulated to reveal new information
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Data Organization
� Byte
� A group of eight bits
� Can store the binary representation of a single character or of a small integer number
� A single unit of addressable memory
� Field
� A group of bytes used to represent a string of
characters
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Data Organization (continued)
� Record
� A collection of related fields
� Data file
� Related records are kept in a data file
� Database
� Related files make up a database
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Figure 13.3
Data Organization Hierarchy
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Figure 13.4
Records and Fields in a Single File
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Figure 13.5
One Record in the Rugs-For-You Employees File
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Database Management Systems
� Database management system (DBMS)
� Manages the files in a database
� Relational database model
� Conceptual model of a file as a two-dimensional table
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Database Management Systems
(continued)
� In a relational database
� A table represents information about an entity
� A row contains data about one instance of an entity
� A row is called a tuple
� Each category of information is called an attribute
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Figure 13.6
Employees Table for Rugs-For-You
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Figure 13.7
InsurancePolicies Table for Rugs-For-You
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Database Management Systems
(continued)
� Specialized query languages
� Enable the user or another application program to query the database
� Example: SQL (Structured Query Language)
� Relationships among different entities in a
database
� Established through the correspondence between primary keys and foreign keys
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Figure 13.8
Three Entities in the Rugs-For-You Database
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Other Considerations
� Performance issues
� Large files are maintained on disk
� Organizing record storage on disk can minimize
time to access a particular record
� Creating additional records to be stored with the
file can significantly reduce access time
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Other Considerations (continued)
� Distributed databases
� Allow physical data to reside at separate and independent locations that are networked
� Massive, integrated government databases raise
legal, political, social, and ethical issues
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Information Security
� Information security
� Data protection, whether on disk or transmitted
across a network
� Authentication: prevent access by hackers
� Encryption: make data meaningless if they do get it
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Encryption Overview
� Cryptography
� The science of “secret writing”
� Plaintext
� A message that is not encoded
� Ciphertext
� An encrypted message
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Encryption Overview (continued)
� Process of encryption and decryption
� Plaintext is encrypted before it is sent
� Ciphertext is decrypted back to plaintext when it is received
� A symmetric encryption algorithm
� Requires a secret key known to both the sender
and receiver
� Sender encrypts the plaintext using the key
� Receiver decrypt the message using the key
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Encryption Overview (continued)
� Asymmetric encryption algorithm
� Also called public key encryption algorithm
� The key for encryption and the key for decryption are different
� Person A makes an encryption key public
� Anyone can encrypt a message using the public
key and send it to A
� Only A has the decryption key and can decrypt the
message
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Simple Encryption Algorithms: Caesar
Cipher
� Caesar cipher
� Also called a shift cipher
� Each character in the message is shifted to
another character some fixed distance farther along in the alphabet
� A stream cipher: encodes one character at a time
� A substitution cipher: a single letter of plaintext
generates a single letter of ciphertext
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Block Cipher
� A group or block of plaintext letters gets
encoded into a block of ciphertext, but not by
substituting one at a time for each character
� Each plaintext character in the block contributes
to more than one ciphertext character
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Block Cipher (continued)
� One ciphertext character is created as a result of
more than one plaintext letter
� Diffusion (scattering) of the plaintext within the
ciphertext
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DES
� Stands for Data Encryption Standard
� Designed to protect electronic information
� A block cipher
� Blocks: 64 bits long
� Key: 64 bit binary key (only 56 bits are actually
used)
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DES (continued)
� Every substitution, reduction, expansion, and
permutation is determined by a well-known set
of tables
� The same algorithm serves as the decryption
algorithm
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Figure 13.11
The DES Encryption Algorithm
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DES (continued)
� Triple DES
� Improves the security of DES
� Requires two 56-bit keys
� Runs the DES algorithm three times
� AES (Advanced Encryption Standard)
� Uses successive rounds of computations that mix
up the data and the key
� Key length: 128, 192, or 256 bits
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Public-Key Systems
� RSA
� Most common public key encryption algorithm
� Based on results from number theory
� If n is a large number, it is extremely difficult to find the prime factors for n
� RSA is often used in the initial stage of communication between client and server
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Figure 13.12
An SSL Session
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Summary
� E-business: every part of a financial transaction
is handled electronically
� Opening an online store requires a significant
amount of planning
� Database: allows data items to be stored,
extracted, sorted, and manipulated
� Relational database model: conceptual model of
a file as a two-dimensional table
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Invitation to Computer Science, C++ Version, Third Edition 49
Summary
� Main parts of information security: encryption
and authentication
� Types of encryption algorithms
� Symmetric encryption algorithms
� Asymmetric encryption algorithms (or public key encryption algorithms)
� Encryption algorithms: Caesar cipher, block
cipher, DES, Triple DES, AES, RSA