Cloud Computing Security From Sngle to multi Clouds Full Documentaion

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Cloud Computing Security From Sngle to multi Clouds Full Documentaion

  1. 1. A Project Report on CLOUD COMPUTING SECURITY FROM SINGLE TO MUTLI CLOUDS Project report submitted in partial fulfillment of the requirement for the award of the Degree of BACHELOR OF TECHNOLOGY IN COMPUTER SCIENCE AND ENGINEERING By N.VAMSEE DEEPAK 10W51A0537 P.JAGADEESH 10W51A0539 Y.SREENIVASULU REDDY 10W51A0551 N.REDDY PRASAD 10W51A0535 Under the Guidance of Y.SHABBIR ALI M.Tech(Ph.D) Associate.Proffessor Sir Vishveshwaraiah Institute of Science & Technology Department of Computer Science & Engineering (Approved by AICTE, Affiliated to JNT University, Ananthapur,) An ISO 9001-2008 Certified Institution Angallu, Madanapalle-517325 2010-2014
  2. 2. A Project Report on CLOUD COMPUTING SECURITY FROM SINGLE TO MUTLI CLOUDS Submitted in partial fulfillment of the requirement for the award of the Degree of BACHELOR OF TECHNOLOGY IN COMPUTER SCIENCE AND ENGINEERING By N.VAMSEE DEEPAK 10W51A0537 P.JAGADEESH 10W51A0539 Y.SREENIVASULU REDDY 10W51A0551 N.REDDY PRASAD 10W51A0535 Under the Esteemed Guidance of Y.SHABBIR ALI M.Tech(Ph.D) Associate. Professor Sir Vishveshwaraiah Institute of Science & Technology Department of Computer Science & Engineering (Approved by AICTE, Affiliated to JNT University, Ananthapur,) An ISO 9001-2008 Certified Institution Angallu, Madanapalle-517325 2010-2014
  3. 3. SIR VISHVESHWARAIAH INSTITUTE OF SCIENCE & TECHNOLOGY Affiliated to JNTU,Anantapur,Approved by AICTE An ISO 9001-2008 Certified Institution Angallu,Madanapalli-517325,Chittor(DT),A.P. Ph:08571-280888,fax:280892,www.svtm.ac.in Department of Computer Science & Engineering CERTIFICATE This is to certify that the project report entitled CLOUD COMPUTING SECURITY FROM SINGLE TO MUTLI CLOUDS is a bonafide work carried out by N.VAMSEE DEEPAK (10W51A0537), P.JAGADEESH (10W51A0539), Y.SREENIVASULU REDDY (10W51A0551), N.REDDY PRASAD (10W51A0535) submitted in the partial fulfillment of the requirements for the award of the degree, Bachelor of Technology in the stream of Computer Science & Engineering in Sir Vishveshwaraiah of Institute of Science & Technology during the academic year 2013-2014. HEAD OF DEPARTMENT PROJECT GUIDE Sri.T. Sunil Kumar Reddy M.Tech (Ph.D)., Sri.Y.Shabbir Ali M.Tech(Ph.D)., Associate Professor Associate Professor Submitted for the University for viva-voice Examination held on ___________________ INTERNAL EXAMINER EXTERNAL EXAMINER
  4. 4. Acknowledgement We are highly indebted to Sri. M.Prabhakar Reddy, Chairman of SVTM, Madanapalle for providing us an excellent academic infrastructure to carry out our projects successfully. We sincerely thank Sri. Dr. K.Sudhakar Reddy, Principal of our college for fostering an excellent academic environment during our project work. We express our heartfelt gratitude to Sri. Dr. L.Suderrshan Reddy, Director for Vishwam Group of Institutions for his continuous support and also for his valuable suggestions throughout the project work. We express our deep sense of gratitude to Sri.T.Sunil Kumar Reddy, Head of the Computer Science and Engineering Department for his pragmatic guidance and constant encouragement throughout the project work. We are thankful to Sri.Y.Shabbir Ali, for his guidance, valuable suggestions and uninterrupted cooperation during my project work. We also express our thanks to Sri.O.DevaKiran, Project Coordinator for his support and encouragement that helped me to complete this project.
  5. 5. We also wish to place on record our gratefulness to all the other faculty members and also to our friends for their help and cooperation during our project work. Finally, a word of gratitude to our family members who have been a constant source of encouragement and love. DECLARATION We are hereby declare that the project report entitled “CLOUD COMPUTING SECURITY FROM SINGLE TO MULTI CLOUDS” was done under the guidance of Sri.Y.Shabbir Ali M.Tech(Ph.D)., is submitted in the partial fulfillment of the requirements of the award of the degree of Bachelor of Technology in Computer Science & Technology during 2010-2014 Date: Place: BATCH MEMBERS Name Roll Number Signature N.VAMSEE DEEPAK 10W51A0537 P.JAGADEESH 10W51A0539 Y.SREENIVASULU REDDY 10W51A0551 N.REDDY PRASAD 10W51A0535
  6. 6. ABSTRACT The use of cloud computing has increased rapidly in many organizations. Cloud computing provides many benefits in terms of low cost and accessibility of data. Ensuring the security of cloud computing is a major factor in the cloud computing environment, as users often store sensitive information with cloud storage providers but these providers may be untrusted. Dealing with “single cloud” providers is predicted to become less popular with customers due to risks of service availability failure and the possibility of malicious insiders in the single cloud. A movement towards “multi-clouds”, or in other words, “interclouds” or “cloud-of-clouds” has emerged recently. This project surveys recent research related to single and multi-cloud security and addresses possible solutions. It is found that the research into the use of multi-cloud providers to maintain security has received less attention from the research community than has the use of single clouds. This work aims to promote the use of multi-cloud due to its ability to reduce security risks that affect the cloud computing user.
  7. 7. CONTENTS NAME OF CONTENTS PAGE NO 1. INTRODUCTION 1 2. LITERATURE SURVEY 4 3. SYSTEM REQUIREMENT SPECIFICATION 3.1 System Analysis 7 3.2 System Study 9 3.3 Software Environment 21 4. SYSTEM DESIGN 29 5. IMPLEMENTATION 43 6. SYSTEM TESTING 6.1 Unit Testing 44 6.2 Integration Testing 45 6.3 Acceptance Testing 46 7. SAMPLE SCREENS 57 8. CONCLUSION AND FUTURE ENHANCEMENTS 58 9. BIBLIOGRAPHY 62
  8. 8. LIST OF FIGURES FIGURE NAME PAGE NO 3.3.1 Working of Java 11 3.3.2 Java platform 14 4.1 Data Flow Diagram 22 4.2 Sequence Diagram 23 4.3 Class Diagram 24 4.4 Component Diagram 25 4.5 Use case Diagram 26 4.6 Activity Diagram 27 4.7 ER Diagram 28
  9. 9. CHAPTER 1 Introduction
  10. 10. INTRODUCTION The use of cloud computing has increased rapidly in many organizations. Subashini and Kavitha argue that small and medium companies use cloud computing services for various reasons, including because these services provide fast access to their applications and reduce their infrastructure costs. Cloud providers should address privacy and security issues as a matter of high and urgent priority. Dealing with “single cloud” providers is becoming less popular with customers due to potential problems such as service availability failure and the possibility that there are malicious insiders in the single cloud. In recent years, there has been a move towards “multi-clouds”, “intercloud” or “cloud-of-clouds”. This project focuses on the issues related to the data security aspect of cloud computing. As data and information will be shared with a third party, cloud computing users want to avoid an untrusted cloud provider. Protecting private and important information, such as credit card details or a patient’s medical records from attackers or malicious insiders is of critical importance. In addition, the potential for migration from a single cloud to a multi-cloud environment is examined and research related to security issues in single and multi-clouds in cloud computing are surveyed. 1
  11. 11. CHAPTER 2 Literature Survey
  12. 12. 2.LITERATURE SURVEY Literature survey is the most important step in software development process. Before developing the tool it is necessary to determine the time factor, economy n company strength. Once these things r satisfied, ten next steps are to determine which operating system and language can be used for developing the tool. Once the programmers start building the tool the programmers need lot of external support. This support can be obtained from senior programmers, from book or from websites. Before building the system the above consideration r taken into account for developing the proposed system. We have to analysis the Knowledge and Data Engineering and Cloud: 2.1 Data & Knowledge Engineering (DKE) Data & Knowledge Engineering (DKE) is a journal in database systems and knowledge base systems. It is published by Elsevier. It was founded in 1985, and is held in over 250 academic libraries.The editor-in-chief is P.P. Chen (Dept. of Computer Science, Louisiana State University, USA) This particular journal publishes 12 issues a year. All articles from the Data & Knowledge Engineering journal can be viewed on indexing services like Scopus and 2.2 Knowledge engineering (KE) KE is an engineering discipline that involves integrating knowledge into computer systems in order to solve complex problems normally requiring a high level of human expertise. At present, it refers to the building, maintaining and development of knowledge- based systems. It has a great deal in common with software engineering, and is used in many computer science domains such as artificial intelligence, including databases, data mining, expert systems, decision support systems and geographic information systems. Knowledge engineering is also related to mathematical logic, as well as strongly involved in cognitive science and socio-cognitive engineering where the knowledge is produced by 2
  13. 13. socio-cognitive aggregates (mainly humans) and is structured according to our understanding of how human reasoning and logic works. Various activities of KE specific for the development of a knowledge-based system:  Assessment of the problem  Development of a knowledge-based system shell/structure  Acquisition and structuring of the related information, knowledge and specific preferences (IPK model)  Implementation of the structured knowledge into knowledge bases  Testing and validation of the inserted knowledge  Integration and maintenance of the system  Revision and evaluation of the system. Knowledge engineering principles Since the mid-1980s, knowledge engineers have developed a number of principles, methods and tools to improve the knowledge acquisition and ordering. Some of the key principles are:  There are different:  Types of knowledge each requiring its own approach and technique.  Types of experts and expertise, such that methods should be chosen appropriately.  Ways of representing knowledge, which can aid the acquisition, validation and re-use of knowledge.  Ways of using knowledge, so that the acquisition process can be guided by the project aims (goal-oriented).  Structured methods increase the efficiency of the acquisition process.  Knowledge Engineering is the process of eliciting Knowledge for any purpose be it Expert system or AI development 3
  14. 14. 2.3 Introduction to Data Mining and Cloud Data mining (also known as Knowledge Discovery in Databases - KDD) has been defined as "The nontrivial extraction of implicit, previously unknown, and potentially useful information from data" It uses machine learning, statistical and visualization techniques to discover and present knowledge in a form which is easily comprehensible to humans. As data and information will be shared with a third party, cloud computing users want to avoid an untrusted cloud provider. Protecting private and important information, such as credit card details or a patient’s medical records from attackers or malicious insiders is of critical importance. In addition, the potential for migration from a single cloud to a multi- cloud environment is examined and research related to security issues in single and multi-clouds in cloud computing are surveyed. 4
  15. 15. CHAPTER 3 System Requirement Specification
  16. 16. 3.1 SYSTEM ANALYSIS Existing System Cloud providers should address privacy and security issues as a matter of high and urgent priority. Dealing with “single cloud” providers is becoming less popular with customers due to potential problems such as service availability failure and the possibility that there are malicious insiders in the single cloud. In recent years, there has been a move towards “multiclouds”, “intercloud” or “cloud-of-clouds”. possibility that there are malicious insiders in the single cloud. Proposed System This project focuses on the issues related to the data security aspect of cloud computing. As data and information will be shared with a third party, cloud computing users want to avoid an untrusted cloud provider. Protecting private and important information, such as credit card details or a patient’s medical records from attackers or malicious insiders is of critical importance. In addition, the potential for migration from a single cloud to a multi-cloud environment is examined and research related to security issues in single and multi-clouds in cloud computing are surveyed. MODULE DESCRIPTION Module Description: 1. Data Integrity 2. Data Intrusion 3. Service Availability 4.DepSKy System Model 5
  17. 17. Data Integrity One of the most important issues related to cloud security risks is data integrity. The data stored in the cloud may suffer from damage during transition operations from or to the cloud storage provider. Cachinet al. give examples of the risk of attacks from both inside and outside the cloud provider, such as the recently attacked Red Hat Linux’s distribution servers. One of the solutions that they propose is to use a Byzantine fault- tolerant replication protocol within the cloud. Hendricks et al. State that this solution can avoid data corruption caused by some components in the cloud. However, Cachinet al.Claim that using the Byzantine fault tolerant replication protocol within the cloud is unsuitable due to the fact that the servers belonging to cloud providers use the same system installations and are physically located in the same place. Data Intrusion According to Garfinkel, another security risk that may occur with a cloud provider, such as the Amazon cloud service, is a hacked password or data intrusion. If someone gains access to an Amazon account password, they will be able to access all of the account’s instances and resources. Thus the stolen password allows the hacker to erase all the information inside any virtual machine instance for the stolen user account, modify it, or even disable its services. Furthermore, there is a possibility for the user’s email(Amazon user name) to be hacked (see for a discussion of the potential risks of email), and since Amazon allows a lost password to be reset by email, the hacker may still be able to log in to the account after receiving the new reset password. Service Availability Another major concern in cloud services is service availability. Amazon mentions in its licensing agreement that it is possible that the service might be unavailable from time to time. The user’s web service may terminate for any reason at any time if any user’s files break the cloud storage policy. In addition, if any damage occurs to any Amazon web service and the service fails, in this case there will be no charge to the Amazon Company for this failure. Companies seeking to protect services from such failure need measures such as backups or use of multiple providers. 6
  18. 18. DepSKy System Model The DepSky system model contains three parts: readers, writers, and four cloud storage providers, where readers and writers are the client’s tasks. Bessani et al. explain the difference between readers and writers for cloud storage. Readers can fail arbitrarily (for example, they can fail by crashing, they can fail from time to time and then display any behavior) whereas, writers only fail by crashing. HARDWARE CONFIGURATION Processor - Pentium –III Speed - 1.1 Ghz RAM - 256 MB(min) Hard Disk - 20 GB Key Board - Standard Windows Keyboard Mouse - Two or Three Button Mouse Monitor - SVGA SOFTWARE CONFIGURATION Operating System : Windows95/98/2000/XP Application Server : Tomcat5.0/6.X Front End : HTML, Java, JSP,AJAX Scripts : JavaScript. Server side Script : Java Server Pages. Database Connectivity : Mysql 7
  19. 19. 3.2 SYSTEM STUDY FEASIBILITY STUDY The feasibility of the project is analyzed in this phase and business proposal is put forth with a very general plan for the project and some cost estimates. During system analysis the feasibility study of the proposed system is to be carried out. This is to ensure that the proposed system is not a burden to the company. For feasibility analysis, some understanding of the major requirements for the system is essential. Three key considerations involved in the feasibility analysis are • ECONOMICAL FEASIBILITY • TECHNICAL FEASIBILITY • SOCIAL FEASIBILITY ECONOMICAL FEASIBILITY This study is carried out to check the economic impact that the system will have on the organization. The amount of fund that the company can pour into the research and development of the system is limited. The expenditures must be justified. Thus the developed system as well within the budget and this was achieved because most of the technologies used are freely available. Only the customized products had to be purchased. TECHNICAL FEASIBILITY This study is carried out to check the technical feasibility, that is, the technical requirements of the system. Any system developed must not have a high demand on the available technical resources. This will lead to high demands on the available technical resources. This will lead to high demands being placed on the client. The developed 8
  20. 20. system must have a modest requirement, as only minimal or null changes are required for implementing this system. SOCIAL FEASIBILITY The aspect of study is to check the level of acceptance of the system by the user. This includes the process of training the user to use the system efficiently. The user must not feel threatened by the system, instead must accept it as a necessity. The level of acceptance by the users solely depends on the methods that are employed to educate the user about the system and to make him familiar with it. His level of confidence must be raised so that he is also able to make some constructive criticism, which is welcomed, as he is the final user of the system. 9
  21. 21. 3.3 Software Environment Java Technology Java technology is both a programming language and a platform. The Java Programming Language The Java programming language is a high-level language that can be characterized by all of the following buzzwords: 1.1. Simple 1.2. Architecture neutral 1.3. Object oriented 1.4. Portable 1.5. Distributed 1.6. High performance 1.7. Interpreted 1.8. Multithreaded 1.9. Robust 2.10. Dynamic 2.11. Secure With most programming languages, you either compile or interpret a program so that you can run it on your computer. The Java programming language is unusual in that a program is both compiled and interpreted. With the compiler, first you translate a program into an intermediate language called Java byte codes —the platform- independent codes interpreted by the interpreter on the Java platform. The interpreter parses and runs each Java byte code instruction on the computer. Compilation happens 10
  22. 22. just once; interpretation occurs each time the program is executed. The following figure illustrates how this works. You can think of Java byte codes as the machine code instructions for the Java Virtual Machine (Java VM). Every Java interpreter, whether it’s a development tool or a Web browser that can run applets, is an implementation of the Java VM. Java byte codes help make “write once, run anywhere” possible. You can compile your program into byte codes on any platform that has a Java compiler. The byte codes can then be run on any implementation of the Java VM. That means that as long as a computer has a Java VM, the same program written in the Java programming language can run on Windows 2000, a Solaris workstation, or on an iMac. 11
  23. 23. The Java Platform A platform is the hardware or software environment in which a program runs. We’ve already mentioned some of the most popular platforms like Windows 2000, Linux, Solaris, and MacOS. Most platforms can be described as a combination of the operating system and hardware. The Java platform differs from most other platforms in that it’s a software-only platform that runs on top of other hardware-based platforms. The Java platform has two components: • The Java Virtual Machine (Java VM) • The Java Application Programming Interface (Java API) You’ve already been introduced to the Java VM. It’s the base for the Java platform and is ported onto various hardware-based platforms. The Java API is a large collection of ready-made software components that provide many useful capabilities, such as graphical user interface (GUI) widgets. The Java API is grouped into libraries of related classes and interfaces; these libraries are known as packages. The next section, What Can Java Technology Do? Highlights what functionality some of the packages in the Java API provide. The following figure depicts a program that’s running on the Java platform. As the figure shows, the Java API and the virtual machine insulate the program from the hardware. Native code is code that after you compile it, the compiled code runs on a specific hardware platform. As a platform-independent environment, the Java platform can be a bit slower than native code. However, smart compilers, well- 12
  24. 24. tuned interpreters, and just-in-time byte code compilers can bring performance close to that of native code without threatening portability. What Can Java Technology Do? The most common types of programs written in the Java programming language are applets and applications. If you’ve surfed the Web, you’re probably already familiar with applets. An applet is a program that adheres to certain conventions that allow it to run within a Java-enabled browser. However, the Java programming language is not just for writing cute, entertaining applets for the Web. The general-purpose, high-level Java programming language is also a powerful software platform. Using the generous API, you can write many types of programs. An application is a standalone program that runs directly on the Java platform. A special kind of application known as a server serves and supports clients on a network. Examples of servers are Web servers, proxy servers, mail servers, and print servers. Another specialized program is a servlet. A servlet can almost be thought of as an applet that runs on the server side. Java Servlets are a popular choice for building interactive web applications, replacing the use of CGI scripts. Servlets are similar to applets in that they are runtime extensions of applications. Instead of working in browsers, though, servlets run within Java Web servers, configuring or tailoring the server. How does the API support all these kinds of programs? It does so with packages of software components that provides a wide range of functionality. Every full implementation of the Java platform gives you the following features: 1.The essentials: Objects, strings, threads, numbers, input and output, data structures, system properties, date and time, and so on. 2. Applets: The set of conventions used by applets. 3. Networking: URLs, TCP (Transmission Control Protocol), UDP (User Data gram Protocol) sockets, and IP (Internet Protocol) addresses. 13
  25. 25. 4. Internationalization: Help for writing programs that can be localized for users worldwide. Programs can automatically adapt to specific locales and be displayed in the appropriate language. 5. Security: Both low level and high level, including electronic signatures, public and private key management, access control, and certificates. 6. Software components: Known as JavaBeansTM , can plug into existing component architectures. 7. Object serialization: Allows lightweight persistence and communication via Remote Method Invocation (RMI). 8. Java Database Connectivity (JDBCTM ): Provides uniform access to a wide range of relational databases. The Java platform also has APIs for 2D and 3D graphics, accessibility, servers, collaboration, telephony, speech, animation, and more. The following figure depicts what is included in the Java 2 SDK. 14
  26. 26. How Will Java Technology Change My Life? We can’t promise you fame, fortune, or even a job if you learn the Java programming language. Still, it is likely to make your programs better and requires less effort than other languages. We believe that Java technology will help you do the following:  Get started quickly: Although the Java programming language is a powerful object-oriented language, it’s easy to learn, especially for programmers already familiar with C or C++.  Write less code: Comparisons of program metrics (class counts, method counts, and so on) suggest that a program written in the Java programming language can be four times smaller than the same program in C++.  Write better code: The Java programming language encourages good coding practices, and its garbage collection helps you avoid memory leaks. Its object orientation, its JavaBeans component architecture, and its wide-ranging, easily extendible API let you reuse other people’s tested code and introduce fewer bugs.  Develop programs more quickly: Your development time may be as much as twice as fast versus writing the same program in C++. Why? You write fewer lines of code and it is a simpler programming language than C++.  Avoid platform dependencies with 100% Pure Java: You can keep your program portable by avoiding the use of libraries written in other languages. The 100% Pure JavaTM Product Certification Program has a repository of historical process manuals, white papers, brochures, and similar materials online. 15
  27. 27.  Write once, run anywhere: Because 100% Pure Java programs are compiled into machine-independent byte codes, they run consistently on any Java platform.  Distribute software more easily: You can upgrade applets easily from a central server. Applets take advantage of the feature of allowing new classes to be loaded “on the fly,” without recompiling the entire program. ODBC Microsoft Open Database Connectivity (ODBC) is a standard programming interface for application developers and database systems providers. Before ODBC became a de facto standard for Windows programs to interface with database systems, programmers had to use proprietary languages for each database they wanted to connect to. Now, ODBC has made the choice of the database system almost irrelevant from a coding perspective, which is as it should be. Application developers have much more important things to worry about than the syntax that is needed to port their program from one database to another when business needs suddenly change. Through the ODBC Administrator in Control Panel, you can specify the particular database that is associated with a data source that an ODBC application program is written to use. Think of an ODBC data source as a door with a name on it. Each door will lead you to a particular database. For example, the data source named Sales Figures might be a SQL Server database, whereas the Accounts Payable data source could refer to an Access database. The physical database referred to by a data source can reside anywhere on the LAN. The ODBC system files are not installed on your system by Windows 95. Rather, they are installed when you setup a separate database application, such as SQL Server Client or Visual Basic 4.0. When the ODBC icon is installed in Control Panel, it uses a file called ODBCINST.DLL. It is also possible to administer your ODBC data sources through a stand-alone program called ODBCADM.EXE. 16
  28. 28. From a programming perspective, the beauty of ODBC is that the application can be written to use the same set of function calls to interface with any data source, regardless of the database vendor. The source code of the application doesn’t change whether it talks to Oracle or SQL Server. We only mention these two as an example. There are ODBC drivers available for several dozen popular database systems. Even Excel spreadsheets and plain text files can be turned into data sources. The operating system uses the Registry information written by ODBC Administrator to determine which low-level ODBC drivers are needed to talk to the data source (such as the interface to Oracle or SQL Server). The loading of the ODBC drivers is transparent to the ODBC application program. In a client/server environment, the ODBC API even handles many of the network issues for the application programmer. The advantages of this scheme are so numerous that you are probably thinking there must be some catch. The only disadvantage of ODBC is that it isn’t as efficient as talking directly to the native database interface. ODBC has had many detractors make the charge that it is too slow. Microsoft has always claimed that the critical factor in performance is the quality of the driver software that is used. In our humble opinion, this is true. The availability of good ODBC drivers has improved a great deal recently. And anyway, the criticism about performance is somewhat analogous to those who said that compilers would never match the speed of pure assembly language. Maybe not, but the compiler (or ODBC) gives you the opportunity to write cleaner programs, which means you finish sooner. Meanwhile, computers get faster every year. JDBC In an effort to set an independent database standard API for Java; Sun Microsystems developed Java Database Connectivity, or JDBC. JDBC offers a generic SQL database access mechanism that provides a consistent interface to a variety of RDBMSs. This consistent interface is achieved through the use of “plug-in” database connectivity modules, or drivers. If a database vendor wishes to have JDBC support, he or she must provide the driver for each platform that the database and Java run on. 17
  29. 29. To gain a wider acceptance of JDBC, Sun based JDBC’s framework on ODBC. As you discovered earlier in this chapter, ODBC has widespread support on a variety of platforms. Basing JDBC on ODBC will allow vendors to bring JDBC drivers to market much faster than developing a completely new connectivity solution. JDBC was announced in March of 1996. It was released for a 90 day public review that ended June 8, 1996. Because of user input, the final JDBC v1.0 specification was released soon after. The remainder of this section will cover enough information about JDBC for you to know what it is about and how to use it effectively. This is by no means a complete overview of JDBC. That would fill an entire book. JDBC Goals Few software packages are designed without goals in mind. JDBC is one that, because of its many goals, drove the development of the API. These goals, in conjunction with early reviewer feedback, have finalized the JDBC class library into a solid framework for building database applications in Java. The goals that were set for JDBC are important. They will give you some insight as to why certain classes and functionalities behave the way they do. The eight design goals for JDBC are as follows:  SQL Level API The designers felt that their main goal was to define a SQL interface for Java. Although not the lowest database interface level possible, it is at a low enough level for higher-level tools and APIs to be created. Conversely, it is at a high enough level for application programmers to use it confidently. Attaining this goal allows for future tool vendors to “generate” JDBC code and to hide many of JDBC’s complexities from the end user.  SQL Conformance 18
  30. 30. SQL syntax varies as you move from database vendor to database vendor. In an effort to support a wide variety of vendors, JDBC will allow any query statement to be passed through it to the underlying database driver. This allows the connectivity module to handle non-standard functionality in a manner that is suitable for its users.  JDBC must be implemental on top of common database interfaces The JDBC SQL API must “sit” on top of other common SQL level APIs. This goal allows JDBC to use existing ODBC level drivers by the use of a software interface. This interface would translate JDBC calls to ODBC and vice versa.  Provide a Java interface that is consistent with the rest of the Java system Because of Java’s acceptance in the user community thus far, the designers feel that they should not stray from the current design of the core Java system.  Keep it simple This goal probably appears in all software design goal listings. JDBC is no exception. Sun felt that the design of JDBC should be very simple, allowing for only one method of completing a task per mechanism. Allowing duplicate functionality only serves to confuse the users of the API.  Use strong, static typing wherever possible Strong typing allows for more error checking to be done at compile time; also, less error appear at runtime.  Keep the common cases simple Because more often than not, the usual SQL calls used by the programmer are simple SELECT’s, INSERT’s, DELETE’s and UPDATE’s, these queries should be simple to perform with JDBC. However, more complex SQL statements should also be possible. 19
  31. 31. Finally we decided to proceed the implementation using Java Networking. And for dynamically updating the cache table we go for MS Access database. Java has two things: a programming language and a platform. Java is a high-level programming language that is all of the following Simple Architecture-neutral Object-oriented Portable Distributed High-performance Interpreted multithreaded Robust Dynamic Secure Java is also unusual in that each Java program is both compiled and interpreted. With a compile you translate a Java program into an intermediate language called Java byte codes the platform-independent code instruction is passed and run on the computer. Compilation happens just once; interpretation occurs each time the program is executed. The figure illustrates how this works. You can think of Java byte codes as the machine code instructions for the Java Virtual Machine (Java VM). Every Java interpreter, whether it’s a Java development tool or a Web browser that can run Java applets, is an implementation of the Java VM. The Java VM can also be implemented in hardware. 20
  32. 32. Java byte codes help make “write once, run anywhere” possible. You can compile your Java program into byte codes on my platform that has a Java compiler. The byte codes can then be run any implementation of the Java VM. For example, the same Java program can run Windows NT, Solaris, and Macintosh. 21
  33. 33. CHAPTER 4 System Design
  34. 34. 4.SYSTEM DESIGN 3.1 Data Flow Diagram The Data-flow diagram is a graphical representation of the “flow” of data through an information system. It differs from the flowchart. Flowchart as it shows the data flow instead of the control flow of the program. A data-flow diagram can also be used for the visualization of Data processing. The system designer makes “a context level DFD” or Level 0, which shows the “interaction”( data flows) between “the system” (represented by one process) and “the system environment” (represented by terminators). The system is “decomposed in lower-level DFD (Level 1)” into a set of “processes, data stores, and the data flows between these processes and data stores.” Each process is then decomposed into an even-lower-level diagram containing its sub processes. 22
  35. 35. Register Service provider Client Login Cloud OwnerUser file User details Verify with Key Verify key with multi-Cloud Hackers information File Spliting Change Password Login Client File upload with spliting File Verify with Multi-Cloud and Download Provider Login File verify 4.2 Sequence Diagram 23
  36. 36. Cloud Owner Client Cloud Server Service Provider File upload to Cloud server File Spliting and Stored multi Cloud Owner Verify the Client File Verifying and generate Key Verify Client File Hackers Information Verify file with Key and Download original File 4.3 Class Diagram 24
  37. 37. 4.4 Component Diagram 25
  38. 38. Cloud Owner Client Homepage Login Verify Files, Verify with Key, User Details File Upload, Verify File with key in Multi Cloud, Original File, File Download Client Service Provider Verify file with multi-Cloud Owner Provider 4.5 Use case Diagram 26
  39. 39. 4.6 Activity Diagram 27
  40. 40. Login Client Register File upload Start End Cloud Owner Service provider File verify Verify with Key File Split with Key Hackers information Verify with key in Multi-Cloud 4.7 ER-Diagram 28
  41. 41. 29
  42. 42. CHAPTER 5 Implementation
  43. 43. SAMPLE CODES package databaseconnection; import java.sql.*; public class databasecon { static Connection con; public static Connection getconnection() { try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost:3306/singlecloud","root","mani"); } catch(Exception e) { System.out.println("class error"); } return con; } } 30
  44. 44. 2- <?xml version="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd"> <taglib> <tlibversion>1.0</tlibversion> <jspversion>1.1</jspversion> <shortname>pg</shortname> <uri>http://jsptags.com/tags/navigation/pager</uri> <info> The Pager Tag Library is the easy and flexible way to implement paging of large data sets in JavaServer Pages (JSP). It can emulate all currently known paging styles with minimal effort. It also includes re-usable index styles that emulate the search result navigators of popular web sites such as Google[sm], AltaVista® and Yahoo!. The Pager Tag Library does most of the work for you by dynamically organizing your data set into pages and generating a browsable index with virtually any look desired. </info> 31
  45. 45. <tag> <name>pager</name> <tagclass>com.jsptags.navigation.pager.PagerTag</tagclass> <teiclass>com.jsptags.navigation.pager.PagerTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>url</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>items</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> 32
  46. 46. <attribute> <name>maxItems</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>maxPageItems</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>maxIndexPages</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>isOffset</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> 33
  47. 47. <name>index</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>scope</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>param</name> <tagclass>com.jsptags.navigation.pager.ParamTag</tagclass> <bodycontent>empty</bodycontent> <attribute> 34
  48. 48. <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>name</name> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>value</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>item</name> <tagclass>com.jsptags.navigation.pager.ItemTag</tagclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> 35
  49. 49. <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>index</name> <tagclass>com.jsptags.navigation.pager.IndexTag</tagclass> <teiclass>com.jsptags.navigation.pager.IndexTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> </tag> 36
  50. 50. <tag> <name>first</name> <tagclass>com.jsptags.navigation.pager.FirstTag</tagclass> <teiclass>com.jsptags.navigation.pager.JumpTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>unless</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> 37
  51. 51. <tag> <name>prev</name> <tagclass>com.jsptags.navigation.pager.PrevTag</tagclass> <teiclass>com.jsptags.navigation.pager.PageTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>ifnull</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> 38
  52. 52. <tag> <name>page</name> <tagclass>com.jsptags.navigation.pager.PageTag</tagclass> <teiclass>com.jsptags.navigation.pager.JumpTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> </tag> <tag> <name>pages</name> <tagclass>com.jsptags.navigation.pager.PagesTag</tagclass> <teiclass>com.jsptags.navigation.pager.PageTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> 39
  53. 53. <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> </tag> <tag> <name>next</name> <tagclass>com.jsptags.navigation.pager.NextTag</tagclass> <teiclass>com.jsptags.navigation.pager.PageTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> 40
  54. 54. <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>ifnull</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>last</name> <tagclass>com.jsptags.navigation.pager.LastTag</tagclass> <teiclass>com.jsptags.navigation.pager.JumpTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> 41
  55. 55. <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>unless</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> <tag> <name>skip</name> <tagclass>com.jsptags.navigation.pager.SkipTag</tagclass> <teiclass>com.jsptags.navigation.pager.PageTagExtraInfo</teiclass> <bodycontent>JSP</bodycontent> <attribute> <name>id</name> <required>false</required> <rtexprvalue>true</rtexprvalue> 42
  56. 56. </attribute> <attribute> <name>export</name> <required>false</required> <rtexprvalue>false</rtexprvalue> </attribute> <attribute> <name>ifnull</name> <required>false</required> <rtexprvalue>true</rtexprvalue> </attribute> <attribute> <required>true</required> <rtexprvalue>true</rtexprvalue> </attribute> </tag> s</taglib> 43
  57. 57. CHAPTER 6 Testing
  58. 58. 6. TESTING 6.1 System Testing The purpose of testing is to discover errors. Testing is the process of trying to discover every conceivable fault or weakness in a work product. It provides a way to check the functionality of components, sub-assemblies, assemblies and/or a finished product It is the process of exercising software with the intent of ensuring that the Software system meets its requirements and user expectations and does not fail in an unacceptable manner. There are various types of test. Each test type addresses a specific testing requirement. 6.2Types of Testing 6.2.1 Functional testing Functional tests provide a systematic demonstration that functions tested are available as specified by the business and technical requirements, system documentation, and user manuals. Functional testing is centered on the following items: Valid Input: Identified classes of valid input must be accepted. Invalid Input: Identified classes of invalid input must be rejected. Functions: Identified functions must be exercised. Output: Identified classes of application outputs must be exercised. Systems/Procedures: Interfacing systems or procedures must be invoked. Organization and preparation of functional tests is focused on requirements, key functions, or special test cases. In addition, systematic coverage pertaining to identify Business process flows; data fields, predefined processes, and successive processes must 44
  59. 59. be considered for testing. Before functional testing is complete, additional tests are identified and the effective value of current tests is determined. 6.2.2.System Testing System testing ensures that the entire integrated software system meets requirements. It tests a configuration to ensure known and predictable results. An example of system testing is the configuration oriented system integration test. System testing is based on process descriptions and flows, emphasizing pre-driven process links and integration points 6.2.3.Unit Testing Unit testing is usually conducted as part of a combined code and unit test phase of the software lifecycle, although it is not uncommon for coding and unit testing to be conducted as two distinct phases. 6.2.4.Test strategy and approach Field testing will be performed manually and functional tests will be written in detail. 6.2.5.Test objectives All field entries must work properly. Pages must be activated from the identified link .The entry screen, messages and responses must not be delayed. 6.2.6 Features to be tested Verify that the entries are of the correct format no duplicate entries should be allowed. All links should take the user to the correct page. 6.3. INTEGRATION TESTING Software integration testing is the incremental integration testing of two or more integrated software components on a single platform to produce failures caused by 45
  60. 60. interface defects. The task of the integration test is to check that components or software applications. E.g. components in a software system or – one step up – software applications at the company level – interact without error. 6.4.ACCEPTANCE TESTING User Acceptance Testing is a critical phase of any project and requires significant participation by the end user. It also ensures that the system meets the functional requirements. Acceptance testing for intranet lives search tax management system: Users have separate roles to modify the database tables. Users should have the ability to modify the privilege for a screen. Test Results: All the test cases mentioned above passed successfully. No defects encountered. 6.5. Summary The purpose of testing is to discover errors. Testing is the process of trying to discover every conceivable fault or weakness in a work product. It provides a way to check the functionality of components, sub-assemblies, assemblies and/or a finished product It is the process of exercising software with the intent of ensuring that the Software system meets its requirements and user expectations and does not fail in an unacceptable manner. Functional tests provide a systematic demonstration that functions tested are available as specified by the business and technical requirements, system documentation, and user manuals. System testing ensures that the entire integrated software system meets requirements. It tests a configuration to ensure known and predictable results and Finally all the test cases are passed no defects are encountered. 46
  61. 61. CHAPTER 7 Sample Screens
  62. 62. Welcome Page Client Register 47
  63. 63. Client Login File Upload 48
  64. 64. File Stored in Multi-Cloud File upload to Multi Cloud 49
  65. 65. Cloud Owner Login User File 50
  66. 66. File Verify Owner File Verified 51
  67. 67. Provider Login File verify 52
  68. 68. Adding Information to Client File 53
  69. 69. While verifying the File it Shown Error After Verify 54
  70. 70. Client verify File with Key Client Verify Server 1 55
  71. 71. Client Verify Server 2 Client Verify Server 3 56
  72. 72. View Original File and Download 57
  73. 73. CHAPTER 8 Conclusions and Future Enhancement
  74. 74. 8.1 CONCLUSION It is clear that although the use of cloud computing has rapidly increased, cloud computing security is still considered the major issue in the cloud computing environment. Customers do not want to lose their private information as a result of malicious insiders in the cloud. In addition, the loss of service availability has caused many problems for a large number of customers recently. Furthermore, data intrusion leads to many problems for the users of cloud computing. The purpose of this work is to survey the recent research on single clouds and multi-clouds to address the security risks and solutions. We have found that much research has been done to ensure the security of the single cloud and cloud storage whereas multi-clouds have received less attention in the area of security. We support the migration to multi-clouds due to its ability to decrease security risks that affect the cloud computing user. 8.2 Future Work For future work, we aim to provide a framework to supply a secure cloud database that will guarantee to prevent security risks facing the cloud computing community. This framework will apply multi-clouds and the secret sharing algorithm to reduce the risk of data intrusion and the loss of service availability in the cloud and ensure data integrity. 58
  75. 75. CHAPTER 9 Bibliography
  76. 76. REFERENCES [1] (NIST), http://www.nist.gov/itl/cloud/. [2] I. Abraham, G. Chockler, I. Keidar and D. Malkhi, "Byzantine disk paxos: optimal resilience with Byzantine shared memory", Distributed Computing, 18(5), 2006, pp. 387-408. [3] H. Abu-Libdeh, L. Princehouse and H. Weatherspoon, "RACS: a case for cloud storage diversity", SoCC'10:Proc. 1st ACM symposium on Cloud computing, 2010, pp. 229-240. [4] D. Agrawal, A. El Abbadi, F. Emekci and A. Metwally, "Database Management as a Service: Challenges and Opportunities", ICDE'09:Proc.25thIntl. Conf. on Data Engineering, 2009, pp. 1709-1716. [5] M.A. AlZain and E. Pardede, "Using Multi Shares for Ensuring Privacy in Database-as-a-Service", 44th Hawaii Intl. Conf. on System Sciences (HICSS), 2011, pp. 1-9. [6] Amazon, Amazon Web Services. Web services licensing agreement, October3,2006. [7] G. Ateniese, R. Burns, R. Curtmola, J. Herring, L. Kissner, Z. Peterson and D. Song, "Provable data possession at untrusted stores", Proc. 14th ACM Conf. on Computer and communications security, 2007, pp. 598-609. [8] A. Bessani, M. Correia, B. Quaresma, F. André and P. Sousa, "DepSky: dependable and secure storage in a cloud-of-clouds", EuroSys'11:Proc. 6thConf. on Computer systems, 2011, pp. 31-46. [9] K. Birman, G. Chockler and R. van Renesse,"Toward a cloud computing research agenda", SIGACT News, 40, 2009, pp. 68-80. 59
  77. 77. [10] K.D. Bowers, A. Juels and A. Oprea, "HAIL: A high-availability and integrity layer for cloud storage", CCS'09: Proc. 16th ACM Conf. on Computer and communications security, 2009, pp. 187-198. [11] C. Cachin, R. Haas and M. Vukolic, "Dependable storage in the Intercloud", Research Report RZ, 3783, 2010. [12] C. Cachin, I. Keidar and A. Shraer, "Trusting the cloud", ACM SIGACT News, 40, 2009, pp. 81-86. [13] C. Cachin and S. Tessaro, "Optimal resilience for erasure-coded Byzantine distributed storage", DISC:Proc. 19thIntl.Conf. on Distributed Computing, 2005, pp. 497-498. [14] M. Castro and B. Liskov, "Practical Byzantine fault tolerance", Operating Systems Review, 33, 1998, pp. 173-186. [15] G. Chockler, R. Guerraoui, I. Keidar and M. Vukolic, "Reliable distributed storage", Computer, 42, 2009, pp. 60-67. [16] Clavister, "Security in the cloud", Clavister White Paper, 2008. [17] A.J. Feldman, W.P. Zeller, M.J. Freedman and E.W. Felten, "SPORC: Group collaboration using untrusted cloud resources", OSDI, October2010, pp. 1-14. [18] S.L. Garfinkel, "Email-based identification and authentication: An alternative to PKI?", IEEE Security and Privacy, 1(6), 2003, pp. 20-26. [19] S.L. Garfinkel, "An evaluation of amazon’s grid computing services: EC2, S3, and SQS", Technical Report TR-08-07, Computer Science Group, Harvard University, Citeseer, 2007, pp. 1-15. [20] E. . Goh, H. Shacham, N. Modadugu and D. Boneh, "SiRiUS: Securing remote untrusted storage",NDSS: Proc. Network and Distributed System Security Symposium, 2003, pp. 131–145. 60
  78. 78. [21] G.R. Goodson, J.J. Wylie, G.R. Ganger and M.K. Reiter, "Efficient Byzantine- tolerant erasure-coded storage",DSN'04: Proc.Intl. Conf. on Dependable Systems and Networks,2004, pp.1-22. [22] E. Grosse, J. Howie, J. Ransome, J. Reavis and S. Schmidt, "Cloud computing roundtable", IEEE Security & Privacy, 8(6), 2010, pp. 17-23. [23] J. Hendricks, G.R. Ganger and M.K. Reiter, "Lowoverhead byzantine fault- tolerant storage", SOSP'07: Proc. 21st ACM SIGOPS symposium on Operating systems principles, 2007, pp. 73-86. [24] A. Juels and B.S. Kaliski Jr, "PORs: Proofs of retrievability for large files", CCS '07: Proc. 14th ACM Conf. on Computer and communications security, 2007, pp. 584- 597. [25] S. Kamara and K. Lauter, "Cryptographic cloud storage", FC'10: Proc. 14thIntl.Conf. on Financial cryptograpy and data security,2010, pp. 136-149. [26] H. Krawczyk, M. Bellare and R. Canetti, "HMAC: Keyed-hashing for message authentication", Citeseer, 1997, pp. 1-11. [27] P. Kuznetsov and R. Rodrigues, "BFTW 3: why? when? where? workshop on the theory and practice of byzantine fault tolerance", ACM SIGACT News, 40(4),2009, pp. 82-86. [28] L. Lamport, R. Shostak and M. Pease, "The Byzantine generals problem", ACM Transactions on Programming Languages and Systems, 4(3), 1982, pp. 382-401. [29] P.A. Loscocco, S.D. Smalley, P.A. Muckelbauer, R.C. Taylor, S.J. Turner and J.F. Farrell, "The inevitability of failure: The flawed assumption of security in modern computing environments", Citeseer, 1998, pp. 303-314. [30] P. Mahajan, S. Setty, S. Lee, A. Clement, L. Alvisi, M. Dahlin and M. Walfish, "Depot: Cloud storage with minimal trust", OSDI'10: Proc. of the 9th USENIX Conf. on Operating systems design and implementation, 2010, pp. 1-16. 61
  79. 79. [31] U. Maheshwari, R. Vingralek and W. Shapiro, "How to build a trusted database system on untrusted storage", OSDI'00: Proc. 4thConf. On Symposium on Operating System Design & Implementation, 2000, p. 10. [32] D. Malkhi and M. Reiter, "Byzantine quorum systems", Distributed Computing, 11(4),1998, pp. 203-213. [33] J.-P. Martin, L. Alvisi and M. Dahlin, "Minimal byzantine storage", DISC '02: Proc. of the 16thIntl. Conf. on Distributed Computing, 2002, pp. 311-325. [34] H.Mei, J. Dawei, L. Guoliang and Z. Yuan, "Supporting Database Applications as a Service", ICDE'09:Proc. 25thIntl.Conf. on Data Engineering, 2009, pp. 832-843. BOOKS [1] ‘Software Engineering’,Roger.S.Pressman Mc.Graw Hill [2] ‘The Unified Modeling Language User Guide’, Grady Booch, James Rumbaugh, Ivar Jacobson. [3] ‘Sotware Project Management’.Walker Rayce. WEBSITES http://java.sun.com http://www.sourcefordgde.com http://www.networkcomputing.com/ http://www.roseindia.com/ http://www.java2s.com/ 62
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