الخميس، 29 نوفمبر 2012

Secure Socket Layer (SSL)


Secure Socket Layer (SSL) is a security protocol that was developed by Netscape Communications Corporation, along with RSA Data Security, Inc. The Primary goal of the SSL protocol is to provide a private channel between communicating applications, which ensures privacy of data, authentication of the partners, and integrity. The Secure Socket Layer (SSL) technology was used for the websites or web applications which need more security.


Schematic representation of the SSL handshake ...
 SSL handshake protocol with two way authentication with certificates. (Photo credit: Wikipedia)

 

Secure Socket Layer (SSL) is composed of two layers:


  • At the lower layer, a protocol for transferring data using a variety of predefined cipher and authentication combinations, called the SSL Record Protocol.
  • On the upper layer, a protocol for initial authentication and transfer of encryption keys, called the SSL Handshake Protocol.

An SSL session is initiated as follows:


  • On the client (browser), the user requests a document with a special URL that starts with https: instead of http: either by typing it into the URL input field, or by clicking the link. For example the major search engines like Google, Yahoo, Bing and other money transactions websites uses Secure Socket Layer (SSL).The client computers which do not installed the Secure Socket Layer (SSL) certificates on their computer unable to browse those sites.
  • The client code recognizes the SSL request and establishes a connection through TCP port 443 to the SSL code on the server.
  • The client then initiates the SSL handshake phase, using the SSL Record Protocol as a carrier. At this point, there is no encryption or integrity checking built into the connection.

The Secure Socket Layer (SSL) Protocol addresses the following security issues:


  • Privacy: After the symmetric key is established in the initial handshake, the messages are encrypted using this key.
  • Integrity: Messages contain a message authentication code (MAC) ensuring the message integrity.
  • Authentication: During the handshake, the client authenticates the server using an asymmetric or public key. It can also be based on certificates. SSL requires that each message is encrypted and decrypted and therefore has a high performance and resource cost.

Secure Socket Layer (SSL) Protocol


The SSL protocol is located at the top of the transport layer. SSL is also a layered protocol itself. It simply takes the data from the application layer, re-formats it, and transmits it to the transport layer. SSL handles a message as follows.

The sender performs the following tasks

  • Takes the message from upper layer.
  • Fragments the data to manageable blocks.
  • Optionally compress the data.
  • Applies a message authentication code (MAC)
  • Encrypts the data.
  • Transmits the result to the lower layer.

 The receiver performs the following tasks.


  • Takes the data from lower layer.
  • Decrypts.
  • Verifies the data with the negotiated MAC key.
  • Decompress the data if compression was used.
  • Reassembles the message.
  • Transmits the message to the upper layer.


An SSL session works in different states. These states are session and connection states. The SSL handshake protocol coordinates the states of the client and the server. In addition, there are read and write states defined to coordinate the encryption according to the change Cipher Spec messages.


Change Cipher Spec Protocol


The change Cipher Spec protocol is responsible for sending change Cipher Spec messages. At any time, the client can request to change current cryptographic parameters such as the handshake key exchange. Following the change Cipher Spec notification, the client sends a handshake key exchange and if available, certificate verify messages, and the server sends a change Cipher Spec message after processing the key exchange message. After that, the newly agreed keys will be used until the next change Cipher Spec request. The change Cipher Spec message is sent after the hello messages during the negotiation.


SSL handshake protocol


The SSL handshake protocol allows the client and server to determine the required parameters for and SSL connection such as protocol version, cryptographic algorithms, optional client or server authentication, and public key encryption methods to generate shared secrets. During this process, all handshake messages are forwarded to the SSL record layer to be encapsulated into special SSL messages. Figure below illustrates an SSL handshake process.



Secure Socket Layer (SSL)



SSL record protocol


After the master key has been determined, the client and server can use it to encrypt application data. The SSL record protocol specifies a format for these messages in general, they include a message digest ensure that they have not been altered and the whole message is encrypted using a symmetric cipher.



Other Internet security methods are: Transport Layer Security (TSL), Pretty Good Privacy (PGP) and Firewall, I will post about them later. Keep following this blog.



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Internet Security & IP Security (IPSec)


English: Encapsulating one IP packet in anothe...
English: Encapsulating one IP packet in another IP packet (Photo credit: Wikipedia)
Internet Security is the securing web server and client (browser) from the possible attacks over the Wide Area Networks or Internet. Internet security is a type of Computer Security or the network Security. It includes mainly specific security protocols like IPSec (Internet Security Protocol), SSL (Secure Socket Layer) or TSL (Transport Layer Security). Internet Security also describes about PGP (Pretty Good Privacy) which is designed to create authenticated and confidential e-mails. It also discuss about Firewalls and Antivirus Programs.


# IP Security (IPSec)


IP Security (IPSec) is collection of protocols designed by Internet Engineering Task Force (IETF) to provide security for a packet at the network level. It helps to create authenticated and confidential packets for the IP layer. IPSec operates in one of the following two modes.


i) Transport Mode


In this mode, IPSec protects what is delivered from the transport layer to the network layer. i.e. the transport mode protects the network layer payload, the payload to be encapsulated in the network layer. This mode does not protect the IP header, i.e. it protects only the packet from the transport layer. In this mode, the IPSec header and trailer are added to the information coming from the transport layer. The IP header is added later. This mode is normally used when we need host-to-host protection of data. The sending host uses IPSec to authenticate and / or encrypt the payload delivered from the transport layer. The receiving host uses IPSec to check the authentication and / or decrypt the IP Packet and deliver it to the transport layer.


ii) Tunnel Mode

 

Internet Security & IP Security



Tunneling or encapsulation is a common technique in packet-switched networks. It consists of wrapping a packet in a new one. That is, a new header is attached to the original packet. The entire original packet becomes the payload of the new one, as shown in Figure. In this mode, IPSec protects the entire IP Packet. It takes an IP packet including the header, applies IPSec security methods to the entire Packet, and then adds a new IP header. The new IP header has different information than the original IP Header.

In general, tunneling is used to carry traffic of one protocol over a network that does not support that protocol directly. For example, NetBIOS or IPX can be encapsulated in IP to carry it over a TCP/IP WAN link. In the case of IPSec, IP is tunneled through IP for a slightly different purpose: To provide total protection, including the header of the encapsulated Packet. Tunneling requires intermediate processing of the original packet while en-route. The destination specified in the outer header, usually and IPSec firewall of router, receives the tunneled packet, extracts the original packet, and sends it to the ultimate destination. The processing cost is compensated by the extra security. A notable advantage of IP tunneling is the possibility to exchange packets with private IP addresses between two intranets over the public Internet, which requires globally unique addresses.


The IPsec framework has three main components, Authentication Header(AH), Encapsulating Security Payload (ESP) and Internet Key Exchange (IKE).


Authentication Header (AH)


AH is used to provide integrity and authentication of IP datagrams. Replay protection is also possible. Although its usage is optional, the replay protection service must be implemented by any IPsec compliant system. The services are connectionless, they work on a per-packet basis. AH is used in two modes, transport mode and tunnel mode.


Encapsulating Security Payload (ESP)

 

English: IP packet with IPsec ESP
English: IP packet with IPsec ESP  (Photo credit: Wikipedia)
ESP is used to provide integrity check, authentication and encryption to IP datagrams. Optional replay protection is also possible. These services are connectionless, in that they operate on a per-packet basis. Encryption can be selected independently of other services. It is highly recommended that, if encryption is enabled, integrity check and authentication be turned on. Like AH, ESP can be used in two ways: Transport mode and tunnel mode.


Internet Key Exchange Protocol (IKE)


The internet Key Exchange (IKE) framework, previously referred to as ISAKMP/Oakley, supports automated negotiation of security Associations, and automated generation and refresh of cryptographic keys. The ability to perform these functions with little or no manual configuration of machines is a critical element to any enterprise-scale IPsec deployment. Internet security association and key management protocol (ISAKMP) is a framework that defines the management of security associations (negotiable, modify, delete) and keys, and it also defines the payloads for exchanging key generation and authentication data. Internet Key exchange (IKE) is a protocol that uses parts of ISAKMP and the Oakley and SKEME key exchange protocols to provide management of keys and security associations for the IPsec AH and ESP protocols and ISAKMP itself.


# Secure Socket Layer (SSL)




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الأربعاء، 28 نوفمبر 2012

Solved MCQ of System Analysis and Design Set-3


 Q.1 A ……………… system in no more than idea.
A) Conceptual
B) Logical
C) Physical
D) None

Q.2 Design Phase consists of …………………….
1.       Identity the functions to be performed
2.       Design the input/output and file design
3.       Defining basic parameters for system design
A) 1 & 2
B) 2 & 3
C) 1 & 3
D) 1, 2 & 3


Q.3 A context diagram
A) Describes the context of a system
B) is a DFD which gives an overview of the system
C) is a detailed description of a system
D) is not used in drawing a detailed DFD

Q. 4 HIPO stand for
A) Hierarchy input process output
B) Hierarchy input plus output
C) Hierarchy plus input process output
D) Hierarchy input output Process

Q.5 Statement of scope and objectives, opportunities and performance criteria ………….
A) Problem definition
B) System analysis
C) System Design
D) Documentation

Q.6 Information can be categorized into …………….
1.       Environmental information
2.       Competitive information
3.       Government information
4.       Internal information
A) 1, 2 & 3
B) 1, 2 & 4
C) 2, 3 & 4
D) 1, 3 & 4

Q.7 System Development process is also called as ……………..
A) System Development Life Cycle
B) System Life Cycle
C) Both A and B
D) System Process Cycle

Q.8 The output of problem definition stage is ……………..
A) Master Development Plan
B) Terms of reference
C) Feasibility report
D) Final product

Q.9 Advantages of system flowcharts ………………….
A) Effective communication
B) Effective analysis
C) Queasier group or relationships
D) All A, B, C

Q.10 Based on the identification of objectives, input, output and file content, the vital document is called …
A) System Definition
B) System Document
C) System Requirement Document
D) System Subject

Q.11 A context diagram is used
A) as the first step in developing a detailed DFD of a system
B) in systems analysis of very complex systems
C) as an aid to system design
D) as an aid to programmer

Q.12 Which of the following is/are the sources for project requests?
A) Request from Department managers
B) Request from senior executives
C) Request from system Analyst
D) All of the above

Q.13 DDS stands for …………………
A) Data Data Systems
B) Data Digital System
C) Data Dictionary Systems
D) Digital Data Service

Q.14 ………….. Phase is a time consuming phase and yet a very crucial phase
A) Feasibility Study
B) Requirement Phase
C) Analysis Phase
D) Testing Phase

Q.15 A DFD is normally leveled as
A) It is a good idea in design
B) It is recommended by many experts
C) it is easy to do it
D) It is easier to read and understand a number of smaller DFDs than one large DFD

Q.16 ………………. is responsible for all aspects of data processing, operation research, organization and method, system analysis and design investments.
A) Management Services Director
B) Data Processing Manager
C) Computer Manager
D) Both B and C

Q.17 ……………… is a tabular method for describing the logic of the decisions to be taken.
A) Decision tables
B) Decision tree
C) Decision Method
D) Decision Data

Q.18 In ……………… system the interaction between various subsystems cannot be defined with certainty
A) Open System
B) Closed System
C) Deterministic System
D) Probabilistic System

Q. 19 State True or False.
1.       Term of reference is the final output of Feasibility Study
2.       Design specification report is the final output of System Analysis
A) 1-true, 2-true
B) 1-false, 2-true
C) 1-true, 2-false
D) 1-false, 2-false

Q.20 The key considerations involved in the feasibility analysis is include
i) Economical      ii) Technical         iii) Behavioral     iv) Personal
A) i, ii, iv              
B) i, ii, iii
C) ii, iii, iv
D) All of the above

Answers:
1.       A) Conceptual
2.       D) 1, 2 & 3
3.       B) is a DFD which .... of the system
4.       A) Hierarchy input process output
5.       A) Problem definition
6.       B) 1, 2 & 4
7.       A) System Development Life Cycle
8.       B) Terms of reference
9.       D) All A, B, C
10.   B) System Document
11.   A) as the first step ... DFD of a system
12.   D) All of the above
13.   C) Data Dictionary Systems
14.   C) Analysis Phase
15.   D) It is easier to ..... one large DFD
16.   A) Management Services Director
17.   A) Decision tables
18.   D) Probabilistic System
19.   D) 1-false, 2-false
20.   B) i, ii, iii

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الثلاثاء، 27 نوفمبر 2012

Solved MCQ of System Analysis and Design Set-2


Q.1 ………… is a sort of blueprint of the system Development Effort.
A) MDP
B) DMP
C) MPD
D) DPM

Q. 2 Data store in a DFD represents.
A) a sequential file
B) a disk store
C) a repository of data
D) a random access memory


Q.3 …………… system consists of programs, data files and documentation
A) Conceptual
B) Logical
C) Physical
D) None of the above

Q.4 …………… is a good example of deterministic system.
A) Life cycle
B) Computer Program
C) Software Program
D) None of the above

Q.5 The main ingredient of the report documenting the ……………… is the cost benefit analysis.
A) System Analysis
B) Feasibility Study
C) System Analyst
D) System Design

Q.6  A data flow can
A) Only a data store
B) Only leave a data store
C) Enter or leave a data Store
D) Either enter or leave a data store but not both

Q.7  Changing the relationship with and services provided to customers in such a way that they will not think of changing suppliers is called ………….
A) Lock in customers
B) Lock out customers
C) Lock in competitors
D) Lock out competitors

Q.8  …………… can be defined as data that has been processed into a form that is meaningful to the recipient and is of real or perceived value in current or prospective decisions.
A) Information
B) Data collection
C) Internal data
D) Sample data

Q.9  Increased volume of sales is an example of ………….…. Benefit. Reduction of bad debts is an example of ………..
A) Tangible, Intangible
B) Tangible, Tangible
C) Intangible, Tangible
D) Intangible, Intangible

Q.10  A data cannot flow between a store and
i) a store              ii) a process        iii) an external entity

A) i and iii
B) i and ii
C) ii and iii
D) ii

Answers:
1.       A) MDP
2.       C) a repository of data
3.       C) Physical
4.       B) Computer Program
5.       B) Feasibility Study

6.       C) Enter or leave a data Store
7.       A) Lock in customers
8.       A) Information
9.       D) Intangible, Intangible
10.   A) i and iii

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الأربعاء، 21 نوفمبر 2012

Data model and Relational Database Model


A data model

               The data model is used to represent real facts of the application. An application may contain many facts however one has to focus only on important facts ignoring the others. For example in case of student details application, student name, roll no, address have to be described however student may also contain other facts like fathers name etc. which may not be relevant.  Some of the salient features that model must may have are listed.
  • Data model mainly describes the data, which gets stored and processed in a given situation.
  • A data model may describe data and various levels and description may be at logical / physical levels or from the point of user.
  • A data model proposes a set of concepts for description of the nature of data and inter-relationships between them along with the syntax.
  • A model should have as minimum concepts, which are close to real world so that user can understand the model and verify.
  • The model should provide primitives by which meaning of data can be captured. The meaning contains type of value data items take their inter-relation to higher level entities and the correctness requirement for them.

Relational Database Model

             Insertion anomalies and redundant data are problems associated with an early database model known as a hierarchical table (parent-child table). Network database (owner-member table) models were problematic as well. These two models led to the development of the relational database model.

The relational model for database management is a database model based on first –order predicate logic (mathematical theories applied by Dr. E. F. Codd). A database model organized in terms of relational model is a relational database model (RDM).

In a RDM, data are stored in a relation or table (those terms may be used interchangeably.) Each table contains rows or records, (also called tuples), and columns which represent attributes or fields. Each record or row is represented by a unique field known as the Primary key. The categories of relationships in a RDM are one-to-one, one-to-many, and many-to-many. A many-to-many relationship must be broken down into numerous one-to-many relationships. If a pair of tables share a relationship, data can be retrieved based on matching values of a shared field between the tables. Data is retrieved by specifying fields and tables using a standard query language known as Structured Query Language (SQL). Most DBMSs (Database Managements Systems) use SQL to build, modify, maintain and manipulate databases. Thorough knowledge of SQL isn’t always necessary since most DMBSs use a graphical interface to generate SQL statements and retrieve data. It is good, however, to have basic knowledge of SQL.



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الثلاثاء، 20 نوفمبر 2012

Database Management System (DBMS)


Data: Data is raw fact or figures or entity. When activities in the organization takes place, the effect of these activities need to be recorded which is known as Data.

          For example, the raw material to be purchased may have many facts like type of raw material, vendor name, address, quantity etc. Likewise Organization will have many transactions and entities which are to be recorded.

Information: Processed data is called information.

A database management system (DBMS) is a collection of program that enables user to create and maintain a database. In other words, the systematic organization of data is called database.

The DBMS is hence general purpose software system that facilities the process of defining constructing and manipulating database for various applications.
  •       Defining a database involves specifying the data types, structures and constraints for the data to be stored in the database.
  •      Constructing the database is the process of storing the data itself on some stored medium that is controlled by the DBMS.
  •       Manipulating database includes such functions as querying the database to retrieve specific data updating the database to reflect change and generation of reports from the data.

DBMS Characteristics

The data processing system should have some characteristics to produce the information. Some of the requirements are listed below.
  •  To incorporate the requirements of the organization, system should be designed for easy maintenance.
  •    Information systems should allow interactive access to data to obtain new information without writing fresh programs.
  •  System should be designed to co-relate different data to meet new requirements.
  •  Data should be stored with minimum redundancy to ensure consist in stored data across different application.
  •  An independent central repository, which gives information and meaning of available data, is required.
  •    Integrated database will helps in understanding the inter-relationships between data stored in different applications.
  •  The stored data should be made available for access by different users simultaneously.
  •  Automatic recovery feature has to be provided to overcome the problems with processing system failure.


Advantage of using a DBMS

The following are the advantages of using DBMS.
1.       Controlling redundancy
2.       Restricting unauthorized access.
3.       Providing persistent storage for program object and data structures.
4.       Permitting interface and actions by using rules.
5.       Providing multiple user interfaces.
6.       Presenting complex relationships among data.
7.       Enforcing integrity constraints.
8.       Providing backup and recovery.


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الاثنين، 12 نوفمبر 2012

E-commerce Security Issues

First of all e-commerce is surrounded by different issues such as commercial, Network infrastructure, Social and Cultural and Security issues are presented below which are important for successful business. E-commerce security issues are frequently aired in the press and are certainly important. Customers are concerned that the item ordered won’t materialize, or be as described. As (much worse) they worry about their social security number and credit card details being misappropriated. However rare, these things do happen, and customers need to be assured that all e-commerce security issues have been covered. Your guarantees and returns policies must be stated on the website and they must be adhered to. Let us first state the security attacks on e-commerce process and Security goals we want to achieve for successful e-commerce.

Attacks on Security
Security attacks can be classified in the following categories depending on the nature of the attacker.

a)      Passive Attacks
The attacker can only eavesdrop or monitor the network traffic. Typically, this is the easiest form of attack and can be performed without difficulty in many networking environments, e.g. broadcast type networks such as Ethernet and wireless networks.

b)      Active Attacks
The attacker is not only able to listen to the transmission but is also able to actively alter or obstruct it. Furthermore, depending on the attackers actions, the following subcategories can be used to cover to cover the majority to cover the majority of attacks.

c)       Eavesdropping
This is attack is used to gain knowledge of the transmitted data. This is passive attack which is easily performed in many networking environments as motioned above. However, this attack can easily perform in many networking environments. However this attack can easily be prevented by using an encryption scheme to protect the transmitted data.

d)      Traffic Analysis
The main goal of this attack is not to gain direct knowledge about the transmitted data, but to extra information from the characteristics of the transmission, e.g. amount of data transmitted, identity of the communicating nodes etc. This information may allow the attacked to deduce sensitive information, e.g., the roes of the communicating nodes, their position etc. Unlike the previously described attack, this one is more difficult to prevent.

e)      Impersonation
Here, the attacker uses the identity of another node to gain unauthorized access to resource or data. This attack is often used as a prerequisite to eavesdropping. By impersonating a legitimate node, the attacker can try to gain access to the encryption key used to protect the transmitted data. Once, this key is known by the attacker, she can successfully perform the eavesdropping attack.


f)       Modification
This attack modifies data during the transmission between the communicating nodes, implying that the communicating nodes do not share the same view of the transmitted data. An example could be when the transmitted data represents a financial transaction where the attacker has modified the transactions value.

g)      Insertion
This attack involves an unauthorized party, who inserts new data claiming that it originates from a legitimate party. This attack is related to that of impersonation.

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    Risk of e-commerce

    As e-commerce evolves, it will present huge risks for those who don’t take advantage of it. The main risk of e-commerce is that the business won’t capitalize on all it has to offer, while the competition moves ahead. The traditional supply chain consists of the manufacturer, the distributor; the traditional supply chain consists of the manufacturer, the distributor, the retailer, and the end consumer. E-commerce is changing this linear view of the supply chain. Instead of goods flowing from one participant to the next, this new online marketplace can connect each participant to the end-consumer. For some links in the supply chain, increased access to customers could be dangerous as partners could even become competitors.

    In the physical world today, there are requirements for documents to be in writing and for hand-written signatures. Such requirements need to be translated into the electronic realm with the rapid development of electronic commerce and to resolve questions raised regarding the applicability of such legislation to the unique features of the electronic regime. The advent or e-commerce and the use of the digital medium as an alternative to the physical, have created some novel legal issues where there are no clear answers.

    The users of information technology must have trust in the security of information and communication infrastructures, network and systems, in the confidentiality, integrity, and availability of data on them, and in the ability to prove the origin and receipt of data. For communication and transactions occurring over a faceless network, there is a need or reliable methods to authenticate a person’s identity and to ensure the integrity of the electronically transmitted documents.

    The concepts of a secure electronic record and a secure electronic signature, and the rebuttable presumptions that flow from that status, are thus necessary for a viable system of electronic commerce. In the context of electronic commerce, none of the usual indicators of reliability present in a paper-based transaction (the use of paper, letterhead, etc.) exist, making it difficult to know when one can rely on the integrity and authenticity of an electronic record. This lack of reliability can make proving one’s case in court virtually impossible. Rebuttable presumptions with respect to secure records and secure signatures put a relying partying a position to know, at the time of receipt and/or reliance, whether the message is authentic and the integrity of its contents intact and, equally important, whether it will be able to establish both of these facts in court in the event of subsequent disputes.

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    Benefits of e-commerce

    Use of e-commerce technologies helps speed up the flow of information and to eliminate unnecessary human intervention; the computer can now accomplish what computers do better than people process routine business transactions quickly and accurately, 24 hours a day. This in turn, frees up people to handle tasks that computers may never be able to do exercising judgment, creativity, and experience to manage exceptions, solve problems and continually improve business processes.

            E-commerce is growing in importance and means unprecedented opportunities for everyone. When a business takes advantage of the power of e-commerce, it will be able to.


            i.            Increase customer satisfaction
    Internet is always open, even on holidays; business is thus always open, 24 hours a day, 7 days a week and 365 days a year. Customers will appreciate the extra access to product updates, shipping details, billing information and more. And since the internet knows no boundaries, customers can shop from home, work, or anywhere they can make a connection. Besides, by connecting the e-commerce and shipping systems, it would be possible to ship products faster and for less money.

          ii.            Increase sales volumes
    The Internet is a new channel to reach new customers. With a web site, a company can automatically become a global provider of goods and services, with an edge over even the largest competitors. Interactive selling is advantageous because a company is no longer limited by shelf-space or inventory concerns but instead offer all products to suit the customers exact specifications.

        iii.            Decrease costs of doing business
    E-commerce helps cut out or streamline processes that eat away profits. For instance exchange of information from advertising to availability updates, can add to the cost of sale. However, the web site can be an efficient, cost-effective communication vehicle. Customers can find timely accurate information in one place when they need it. By using e-commerce, everything from purchase orders to funds transfer can be handled faster and more efficiently. Even payment processing and bookkeeping are easier.


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    الأحد، 11 نوفمبر 2012

    Development of e-commerce

    Now, most of the companies are using e-commerce technology and going to be used. Even small companies have their own web sites, giving details about their profile, Products and services and are moving up in the e-commerce value chain. Companies that were earlier providing access to information on their respective web sites are now engaging themselves in e-commerce practices. Some of the e-commerce practices which are being done by most of the companies for the development of e-commerce technology for them are as follows.

    a) Better Information technology infrastructure

            E-business models are moving from the proprietary ‘Electronic Data Interchange’ (EDI) ‘Specific’ solutions to internet based ‘mass’ solutions. It has more to do with better computer penetration, increase in number of internet users and high-speed connectivity rather than anything else.

    b) Wider acceptance of online payment system

            Online payment mechanism means ‘payment’ and ‘acceptance’ of virtual money. Any such online payment system requires not only the parties transacting business over the Internet but also a ‘payment gateway’ facilitating such transactions. To begin with, it requires use of credit cards and other modes of online payment using advanced technological tools.

              Master Card has recently introduced Site Data Protection Service (SDP), a comprehensive set of global e-business security services that proactively protects online merchants from hacker intrusions. It is a satellite communications network. Also credit card companies have come out with a technology that proactively helps prevents and skimming by using the ‘intrinsic noise’ properties of magnetic strip, which are unique for every card, to differentiate between and original and cloned cards.

    Apart from credit card based transactions, other proprietary online payment systems to initiate the ‘uninitiated’ to shop on the Internet are:

    • Cybercash: Ensuring encrypted passage over the internet for the data card data.
    • E-Cash: Issued online for use over the Internet and is stored in an electronic device such as a chip card of computer memory. The person who has purchased such cash can use it online for making payments.
    • Online Pay: Online Pay allows consumers to shop online without fear of fraud by allowing them to make purchases without giving out information about their credit card or their checking account to the online vendor.
    • Secure Sockets Layers: It is developed by Netscape, which provides privacy, integrity and authentication through digital certificates. Increasing use of Smart Card has also given fillip to the e-commerce activities. Smart cards store all their information on a chip buried within the card. It works as an electronic purse storing digital money, which could be used over public terminals (Web sites, ATMs, Telephone lines) etc. A new system of credit card transactions over the Internet is being currently developed jointly by Visa and MasterCard with technical assistance from the Internet Information system and cryptology companies like Netscape, IBM. It is known to Secure Electronic Transactions (SET). It is expected that in coming years, SET would become the standard of payment over the Internet. Another important development has the adoption of digital signatures as authentication standards providing integrity, confidentiality and non-repudiation of electronic records. It has paved the way for legal recognition of electronic contracts, an extremely important step in giving legal sanctity to online payment system.

    c) Legal recognition to e-commerce practices. 

          Legal recognition of E-commerce practices has come a long way from the initial adoption of UNCITRAL’s Model Law on Electronic commerce by the General Assembly of the United Nations in early 1997. The purpose of the UNCITRAL Model Law on electronic ecommerce is to encourage the use of electronic commerce and to provide nations with model legislation “governing the use of alternative to paper – based methods of communication and storage of information”. It is based on “fundamental-equivalent” approach and extends notions such as “writing”, “signature” and “original” of traditional paper based requirements to a paperless world. It gives legal acceptance to electronic records and digital signatures. Countries, by adopting the UNCITRAL’s Model Law on Electronic commerce have not only given credence to E-commerce laws globally. The most important element is that the nations’ laws on e-commerce have been based on a similar technology platform, i.e. asymmetric cryptography.


    d) Adoption of security standards by the industry

            Business thrives on safety, security and trust whether it is offline or online. The internet being an open, integrated and public system requires far better security coverage than its offline counterpart. It needs an ‘encryption’ technology that provides (i) confidentially (ii) authentication (iii) Integrity (iv) non repudiation and of electronic transactions.

    1. Confidentiality: The idea that the information should be protected from unauthorized internal as well as external users by making it undecipherable. It uses encryption technology to ‘encrypt’ the information in such a way that only an intended user could ‘decrypt’ the information.
    2. Authentication: It means use of encryption technology to identify the sender of originator of the information. Similarly it should be possible to ensure that the message is sent to the person of whom it is meant.
    3. Integrity: It is to verify that the information, which is received, has not been manipulated during its transmission. On retrieval or receipt at the other end of a communication network the information should appear exactly as it was stored or sent by the sender of originator.
    4. Non-repudiation: It is ensure that sender or originator cannot disown information at a later date. Encryption technologies make it possible to bind messages and message acknowledgements with their originators. 

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    الخميس، 8 نوفمبر 2012

    Definition of Tree


    A tree is a combination of a finite set of elements, called nodes and a finite set of directed lines, called branches that connect the nodes.

    The number of branches associated with a node is the degree of the node. When the branch is directed towards the node, it is an indegree branch. When the branch is directed away from the node, it is an out degree branch, the sum of outdegree and indegree branches equal to the degree of the node.

    Some important terms:

    Definition of Tree
      Definition of Tree
    • Root node: If the tree is non empty, then the first node is called as root. The indegree of root by definition is zero.
    • Leaf node: A node with no successors (nodes after it). There will usually be many leaves in a tree.
    • Non Leaf node: A node which has both a parent and at least one child.
    • Internal nodes: Nodes that are not root and not leaf are called as internal nodes
    • Parent node: A node is a parent if it has successor nodes; means out degree greater than zero.
    • Child node: A node is child node if indegree is one.
    • Siblings: Two or more nodes with same parent are siblings.
    • Ancestor node: An ancestor is any node in the path from the root to the node.
    • Descendant node: A descendent is any node on the path below the parent node.
    • Subtree: A subtree is any connected structure below the root.
    • Directed tree: A directed tree is an acyclic digraph, which has only one node with indegree 0, and others nodes have indegree 1.
    • Binary tree: A binary tree is a tree in which no node can have more than two subtrees. In other word it is a directed tree in which outdegree of each node is less than or equal to two. (i.e. zero, one or two). An empty tree is also a binary tree.
    • Strictly binary tree: If the outdegree of every node in a tree is either 0 or 2, then the tree is said to be strictly binary tree. i.e. each node can have maximum two children or empty left and empty right child.
    • Complete binary tree: A strictly binary tree in which the number of nodes at any level i is 2 i-1 then the tree is said to be complete binary tree.
    • Almost binary tree: A tree of depth d is an almost complete binary tree, if the tree is complete up to the level d-1.
    • Tree traversals: Tree traversal is the technique in which each node in the tree is processed or visited exactly once systematically one after the other. The different tree traversal techniques are Inorder, Preorder and Postorder.Algorithm for tree traversal
         i) Inorder (Left-Root-Right)
    • Traverse the left sub tree in inorder [L]
    • Process the root node [N]
    •  Traverse the right sub tree in inorder [R]
         ii) Preorder (Root-Left-Right)
    • Process the root node [N]
    • Traverse the left sub tree in preorder [L]
    • Traverse the right sub tree in Preorder [R]
         iii) Postorder (Left-Right-Root)
    • Traverse the left subtree in post order. [L]
    • Traverse the Right sub tree in postorder [R]
    • Process the root node [N]
    Binary Search tree: A binary search tree is a binary tree in which for each node say x in the tree elements in the left subtree are less than info(x) and elements in the left subtree are greater or equal to info(x).

    The operations performed on binary search tree are:

    •  Insertion: An item is inserted
    •  Searching: Search for a specific item in the tree.
    •  Deletion: Deleting a node from a given tree.

      Balanced Search trees: Balanced search tree is on that exhibits a good ratio of breadth to depth. There are special classes of Balanced Search Trees that are self-balancing. That is as new nodes are added or existing nodes are deleted, these Balanced search Trees automatically adjust their topology to maintain an optimal balance. With an ideal balance, the running time for inserts, searches, and deletes even in the worst case is log2n.
      AVL trees, Red-Black trees, Lemma are the examples of balanced search trees.


      AVL Trees: An AVL tree is a binary search tree whose left subtree and right subtree differ in height by at most 1 unit, and whose left and right trees are also AVL trees.
      To maintain balance in a height balanced binary tree, each node will have to keep an additional piece of information that is needed to efficiently maintain balance in the tree after every insert and delete operation has been performed. For an AVL tree, this additional piece of information is called the balance factor and it indicates if the difference in height between the left and right subtrees is the same or, if not, which of the two subtrees has height one unit larger. If a node has a balance factor rh(right high). It indicates that the height of the left subtree. Similarly the balance factor for a node could be lh(left height) or eh(equal height).



      Binary Heap tree: A binary heap is a complete binary tree. A tree that is completely filled except possibly at the bottom level, which is filled from left to right with no missing nodes.
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