Transcript SYSTEM SOFTWARE Lab. 일자: 98-03-19

Secure Electronic Commerce
( Chap.2 The Internet )
System software laboratory
석사 2 학기
박정호
SYSTEM SOFTWARE Lab.
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Computer Networking
Distributed Application
Single PC application - W.P, spreadsheets
Multiple PC application - E-mail Distributed Application
Computer network - transferring data between systems
System
Equipment which is connected to a computer network
H/W & S/W running on that equipment
• ex) A network-connected desktop PC, ATM, POS devices
Client-server applications
server
File server
Database server
Mail server
Information-retrieval server
End-user
Client system
…...
End-user
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cont’d
Computer Networks
Data item
Conveyed from one system to another
Representation of a information
Protocol
Set of rules understood by systems that intercommunicate
Multiple layer of protocol
•
operate independently of each other
Link or subnetwork layer
•
protocol to support the transfer of a string of data bits
Network layer
•
•
protocol to support the delivery of a packet Transport layer
protocol to ensure that all data packet deliver and no packets are lost
Application layer
•
protocol understood by the application S/W components in the end-systems
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TCP/IP 프로토콜 계층
ISO Model (OSI)
TCP/IP Model
APPLICATIONS
Layer 7
Application
Layer 6
Presentation
FTP
SMTP
TELNET
X-WINDOWS
LPR, LPD
REXEC
Application
Layer 5
Session
Stream sockets
Layer 4
Transport
Transport
Layer 3
Network
Internet
Layer 2
Link
Layer 1
Physical
KERBEROS
DNS
USER
RPC
NFS
PORTMAP
TCP
Segments
TFTP
SNMP
ROUTED
NCS
Datagram sockets
ports
UDP
Datagrams
ICMP
ARP RARP
INTERNET PROTOCOL
IP address
NETWORK INTERFACE
AND HARDWARE
Network
Interface
and
Hardware
MAC address
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cont’d
Internet
Both a technology and a live, massive computer network
Foundation
U.S Department of Defense in 1969
Support the establishment of connections between computers
Expansion
 ARPA (DARPA) in 1970s
•
interconnecting computers in University and government research institutions
across the U.S.
• become available for commercial exploitation and international
Main technological achievement
 Development of public-domain network protocols
Two protocols
Transmission Control Protocol(TCP) : transport layer
 Internet Protocol(IP) : network layer
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Internet Applications
Electronic
messaging
(e-mail)
Remote login
(Telnet)
Network news
(Newsgroup)
Information
browsing
(Gopher)
World Wide Web
(WWW)
Wide Area
Information
Service(WAIS)
File transfer
(FTP)
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Cont’d
Electronic Messaging
Send a message to one or more recipients
Mail server
X.400
X.400
Mail gateway
S1…..S2
Mail server
R1…..R2
Has some problem
• message compromise only text
• must deal with multimedia data
Multipurpose Internet Mail Extensions(MIME)
• transfer of structured, multimedia messages
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Cont’d
World Wide Web
Support the delivery of hypermedia documents
• Contain multimedia information
• Include hypertext references(links) to other documents
• HTTP(Hyper Text Transfer Protocol)
– application layer to access webserver
Has a unique identifier
user
N.C
I .E
etc
Browser
HTTP
URL
WEB server
SYSTEM SOFTWARE Lab.
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Internet Community
Internet Access
provider
Host-based Service
provider
Internet content
provider
InterNIC Assigned
Numbers
Authority(IANA)
InterNIC Directory
and Database
Services
The InterNIC
Internet Service Providers
Internet
Users
Internet Activities Board
Internet Engineering
Task Force(IETF)
Internet Research
Task Force(IRTF)
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SYSTEM SOFTWARE Lab.
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cont’d
Internet Activities Board and Internet Standards
IESG
IETF
IRTF
IAB
Standards track
 Proposed standard
 Draft standard
 Standard
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Cont’d
InterNIC(Internet Network Information Center)
Major component of the Internet’s infrastructure
InterNIC directory and database services
•
operated by AT&T Corp
•
including distribution of many Internet publications
InterNIC registration services
• provided by Network Solutions, Inc.
• support Domain
– the assignment of names to network or organization
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인터넷의 IP 주소 체계
8
클래스 A
1 네트워크 주소(7)
클래스 B
1 0
클래스 C
1 1 0
클래스 D
1 1 1 0
클래스 E
1 1 1 1 0
클래스
16
24
호스트주소(24)
네트워크 주소(14)
네트워크 수
호스트주소(16)
네트워크 주소(21)
호스트주소(8)
다중 전송용(Multicast) 주소(28)
예약(27)
호스트 수
(네트워크 당)
주소 범위
A
27 = 128
224 = 16,777,216
0.0.0.0 – 127.255.255.255
B
214 = 16,384
216 = 65,536
128.0.0.0 – 191.255.255.255
C
221 = 2,097,152
28 = 256
192.0.0.0 – 223.255.255.255
D
228 = 268,435,456
224.0.0.0 – 239.255.255.255
E
227 = 134,217,728
240.0.0.0 – 247.255.255.255
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Cont’d
Service Providers
Access service
Host-based services
Content
 Internet Publications
Requests for Comments (RFC) series
Another important series - Internet Drafts
Working Together for Security
RFC1281(guideline for the secure operation of the internet)
• work together to achieve a secure environment
– users
– computer and network service provider
– vendors and system developers
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EC on the Internet
 EDI
 Electronic Data Interchange
 One of the forms of electronic commerce
The X12 standards
The EDIFACT standards
• Purchase orders
• Invoices
• Payment advices
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cont’d
EDI
+
VAN
Client
• Data communications services
• Software, security, recovery of lost data
transaction tracing, auditing
EDI
Client
• Communications lines
• Dial up links
• Mainframe terminal emulation
• Packet-switching data networks
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cont’d
VAN
Client
• High cost
EDI VANS
Client
Internet
• Low cost
• Didn’t provide basic data communications service
• Provide auxiliary service
• Using the natural technology of electronic massaging
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cont’d
EDI
Internet
Client
MIME
• Providing an ideal framework
EDI User
EDI User
• Using the MIME content type
• MIME have three content types
VAN
Another
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cont’d
• Open Electronic Commerce
EDI transactions
Buyers
• technical & administrative protocols
• legal agreements
require
Sellers
• Finding easily
• Goods
• Service
WEB
E-mail
• Business agreements
• Paper documents
• New electronic commerce
Without pre-negotiated, customized, bilateral agreements
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Example Transaction Scenarios
Vera Buys a Lathe
Web
Decides on a model offered by Danielle’s Machine Markers
Investigates the vendor electronically
Fills out the electronic order form
Transmits the order via the internet
Vera
Danielle :
Vera
:
Danielle :
Checks the order and confirms the order by returning an electronic
invoice
Pays for the lathe using a network-based process
Delivers the lathe to Vera’s manufacturing
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Example Transaction Scenarios
Vera Buys a Lathe
Launches Web broswer
lathe 검색
lathe 목록 표시


모델 결정
전자주문서 작성 및 전송
송장 수신
Vera
요금 지불
- 신용카드.
- 전자화폐
Lathe 수취


Internet
전자주문서 수신

송장 발송

Lathe 탁송

Danielle’s
Machine
Marker
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cont’d
Inter-corporate Trading
Using e-mail-based electronic commerce
Because e-mail present too many risks
Needs to incorporate the following safeguards
Originator of every message must be securely authenticated
All messages must be confidentiality-protected
Nola’s Electronic Market
Faces some substantial risks because she don’t know who they are
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Summary
Computer network
means for transferring data
depends on network protocol
Internet
public network + private network
internet protocol = TCP/IP
Internet application
electronic messaging & WWW
MIME(Multi-purpose Internet Mail Extensions)
Internet community
users, service providers, IAB(Internet Activities Board), InterNIC
EC(Electronic Commerce)
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