Cloud storage allows users to store data in the cloud without managing local hardware. It provides on-demand access to cloud applications and pay-per-use services. The document discusses different cloud service models including SaaS, PaaS, and IaaS. It proposes a system to ensure correctness of user data in the cloud with dynamic data support and distributed storage. The system features include auditing by a third party, file retrieval and error recovery, and cloud operations like update, delete, and append.

2. Introduction
 Cloud storage enables users to remotely store their
data and enjoy the on-demand high quality cloud
applications without the burden of local hardware and
software management.
 It provides pay per use service .

3. Cloud Services
 Saas : Software as a service model you with access to application softwares .
No installation, setup required for running the application. Service
provider will provide us. We just have to pay and use it.
Examples : Google Apps, Microsoft Office 365. etc…
 Paas :
Platform as a service provides computing platforms which
includes operating system, programming language execution environment,
database, web server etc.
Examples : AWS Elastic Beanstalk, Force.com, Google App Engine etc…
 Iaas :
Infrastructure as a service, provides you the computing
infrastructure, and other resources like virtual-machine disk image library,
block and file-based storage, firewalls, load balancers, IP addresses,
virtual local area networks(LAN) etc.
Examples : Amazon EC2, Windows Azure, Rackspace etc…

4. Existing systems
 Cloud Computing moves the application software and
databases to the large data centers, where the
management of the data and services may not be fully
trustworthy.
Disadvantage:
 In the existing system there is no privacy to the user’s
data.
 Security risks towards the correctness of the data in
cloud.

5. Proposed systems
In the proposed systems we provide the security to
ensure the correctness of users data in the cloud, we
propose an effective and flexible distributed scheme
with two salient features.

6. features
 In this system, we propose an effective and flexible
distributed scheme with explicit dynamic data support
to ensure the correctness of users’ data in the cloud.
 Cloud Computing is not just a third party data
warehouse. The data stored in the cloud may be
frequently updated by the users, including insertion,
deletion, modification, appending, etc.. on their
specific data blocks.

7. System Requirement
Specification(SRS)
 Functional Requirements.
 Non-functional Requirements.
 Software Requirements.
 Hardware Requirements.

8. Functional Requirements
 Functional Requirements refer to very important system
requirements in a software engineering process such as
technical specifications, system design ,data manipulation,
data processing and calculation modules etc.
 Requirement is based on parameters of system
performance, software quality attributes, reliability and
security, cost, constraints in design/implementation etc.

9. Non-functional requirements
All the other requirements which do not form a part of the above specification are
categorized as Non-Functional Requirements.
Sufficient network bandwidth may also be a non-functional requirement of a system.
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Examples:
Security
Accessibility
Availability
Backup
Disaster Recovery
Efficiency
Open Source
Operability
Performance
Platform compatibility
Recoverability etc…..

10. Software Requirements
 Operating system
 Coding Language
 Data Base
: Windows XP.
: ASP.Net with C#
: SQL Server 2005

11. Hardware Requirements
 System
 Hard Disk
 Floppy Drive
 Monitor
 Mouse
 Ram
: Pentium IV 2.4 GHz.
: 40 GB.
: 1.44 Mb.
: 15 VGA Colour.
: Logitech.
: 512 Mb.

12. Block/Architectural diagram

13. Module Design
 System module
 File retrieval & Error Recovery
 Third party Auditing
 Cloud Operations.

14. System module
 User: users, who have data to be stored in the cloud and rely on
the cloud for data computation, consist of both individual
consumers and organizations.
 Cloud Service Provider (CSP): CSP provides building and
managing distributed cloud storage servers, owns and operates
live Cloud Computing systems.
Examples: Microsoft , IBM , Google etc….
 Third Party Auditor (TPA): an optional TPA, who has expertise
and capabilities that users may not have, is trusted to assess and
expose risk of cloud storage services on behalf of the users upon
request.

15. File retrieval & Error recovery
 The user can reconstruct the original file by
downloading the data vectors from the first ‘m’ servers,
assuming that they return the correct response values.
 We can guarantee the successful file retrieval with
high probability.

16. Third party Auditing(TPA)
 In case the user does not have the time, feasibility or
resources to perform the storage correctness verification,
he can optionally delegate this task to an independent
third party auditor, making the cloud storage publicly
verifiable.
 TPA should not learn user’s data content through the
delegated data auditing.

17. Cloud Operations
 Update operation :
In cloud data storage, the user can modify some data
block(s) stored in the cloud, we refer this operation as
data update.
In other words, for all the unused tokens, the user needs
to exclude every occurrence of the old data block and
replace it with the new one.

18. Cloud operations
 Delete Operation :
After data being stored in the cloud, certain data
block(s) may need to be deleted. The delete operation
we are considering is a general one, in which user
replaces the data block with zero or some special
reserved data symbol.

19. Cloud operations
 Append Operation :
In some cases, the user may want to increase the size of
his stored data by adding blocks at the end of the data
file, which we refer as data append.
 In cloud data storage is bulk append, in which the
user needs to upload a large number of blocks (not a
single block) at one time.

20. Conclusion
 By using cloud computing technology the users can
access the data as well as the users can store the huge
data to their data blocks instead of storing to their
local hardware system.
 In the cloud,the data is secure ,the unauthorized users
cannot access to the data stored in it..