Panda: Public Auditing for Shared Data with Efficient User Revocation in the Cloud

  • September 22, 2015
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Panda: Public Auditing for Shared Data with Efficient User Revocation in the Cloud

ABSTRACT:

With data storage and sharing services in the cloud, users can easily modify and share data as a group. To ensure shared data integrity can be verified publicly, users in the group need to compute signatures on all the blocks in shared data. Different blocks in shared data are generally signed by different users due to data modifications performed by different users. For security reasons, once a user is revoked from the group, the blocks which were previously signed by this revoked user must be re-signed by an existing user. The straightforward method, which allows an existing user to download the corresponding part of shared data and re-sign it during user revocation, is inefficient due to the large size of shared data in the cloud. In this paper, we propose a novel public auditing mechanism for the integrity of shared data with efficient user revocation in mind. By utilizing the idea of proxy re-signatures, we allow the cloud to resign blocks on behalf of existing users during user revocation, so that existing users do not need to download and re-sign blocks by themselves. In addition, a public verifier is always able to audit the integrity of shared data without retrieving the entire data from the cloud, even if some part of shared data has been re-signed by the cloud. Moreover, our mechanism is able to support batch auditing by verifying multiple auditing tasks simultaneously. Experimental results show that our mechanism can significantly improve the efficiency of user revocation.

EXISTING SYSTEM:

  • In existing mechanisms, a signature is attached to each block in data, and the integrity of data relies on the correctness of all the signatures.
  • One of the most significant and common features of these mechanisms is to allow a public verifier to efficiently check data integrity in the cloud without downloading the entire data, referred to as public auditing. This public verifier could be a client who would like to utilize cloud data for particular purposes or a thirdparty auditor (TPA) who is able to provide verification services on data integrity to users.
  • With shared data, once a user modifies a block, she also needs to compute a new signature for the modified block. Due to the modifications from different users, different blocks are signed by different users.
  • For security reasons, when a user leaves the group or misbehaves, this user must be revoked from the group. As a result, this revoked user should no longer be able to access and modify shared data, and the signatures generated by this revoked user are no longer valid to the group. Therefore, although the content of shared data is not changed during user revocation, the blocks, which were previously signed by the revoked user, still need to be re-signed by an existing user in the group. As a result, the integrity of the entire data can still be verified with the public keys of existing users only.

DISADVANTAGES OF EXISTING SYSTEM:

  • Straightforward method may cost the existing user a huge amount of communication and computation resources.
  • The number of re-signed blocks is quite large or the membership of the group is frequently changing.

PROPOSED SYSTEM:

  • In this paper, we propose Panda, a novel public auditing mechanism for the integrity of shared data with efficient user revocation in the cloud.
  • In our mechanism, by utilizing the idea of proxy re-signatures, once a user in the group is revoked, the cloud is able to resign the blocks, which were signed by the revoked user, with a re-signing key. As a result, the efficiency of user revocation can be significantly improved, and computation and communication resources of existing users can be easily saved. Meanwhile, the cloud, which is not in the same trusted domain with each user, is only able to convert a signature of the revoked user into a signature of an existing user on the same block, but it cannot sign arbitrary blocks on behalf of either the revoked user or an existing user.
  • By designing a new proxy re-signature scheme with nice properties, which traditional proxy resignatures do not have, our mechanism is always able to check the integrity of shared data without retrieving the entire data from the cloud. Moreover, our proposed mechanism is scalable, which indicates it is not only able to efficiently support a large number of users to share data and but also able to handle multiple auditing tasks simultaneously with batch auditing.
  • In addition, by taking advantages of Shamir Secret Sharing, we can also extend our mechanism into the multi-proxy model to minimize the chance of the misuse on re-signing keys in the cloud and improve the reliability of the entire mechanism.

ADVANTAGES OF PROPOSED SYSTEM:

  • It follows protocols and does not pollute data integrity actively as a malicious adversary.
  • Cloud data can be efficiently shared among a large number of users, and the public verifier is able to handle a large number of auditing tasks simultaneously and efficiently.

SYSTEM ARCHITECTURE:

9

MODULES

User Module:

  • Registration
  • File Upload
  • Download
  • Reupload
  • Unblock module

Auditor Module:

  • File Verification module
  • View File

Admin Module:

  • View Files
  • Block user

MODULES DESCRIPTION:

User Module:

Registration:

In this module each user registers his user details for using files. Only registered user can able to login in cloud server.

File Upload:

In this module user upload a block of files in the cloud with encryption by using his secret key. This ensures the files to be protected from unauthorized user.

Download:

This module allows the user to download the file using his secret key to decrypt the downloaded data of blocked user and verify the data and reupload the block of file into cloud server with encryption .This ensure the files to be protected from unauthorized user.

Reupload:

This module allow the user to reupload the downloaded files of blocked user

into cloud server with resign the files(i.e) the files is uploaded with new signature like new secret with encryption to protected the data from unauthorized user.

Unblock Module:

This module allows the user to unblock his user account by answering his security question regarding to answer that provided by his at the time of registration. Once the answer is matched to the answer of registration time answer then only account will be unlocked.

Auditor Module:

File Verification module:

The public verifier is able to correctly check the integrity of shared data. The public verifier can audit the integrity of shared data without retrieving the entire data from the cloud, even if some blocks in shared data have been re-signed by the cloud.

Files View:

In this module public auditor view the all details of upload, download, blocked user, reupload.

Admin Module:

View Files:

In this module public auditor view the all details of upload, download, blocked user, reupload.

Block User:

In this module admin block the misbehave user account to protect the integrity of shared data

SYSTEM REQUIREMENTS:

HARDWARE REQUIREMENTS:

 

  • System :         Pentium IV 2.4 GHz.
  • Hard Disk :         40 GB.
  • Floppy Drive : 44 Mb.
  • Monitor : 15 VGA Colour.
  • Mouse :
  • Ram : 512 Mb.

SOFTWARE REQUIREMENTS:

  • Operating system : Windows XP/7.
  • Coding Language : net, C#.net
  • Tool : Visual Studio 2010
  • Database : SQL SERVER 2008

REFERENCE:

Boyang Wang, Baochun Li, Member, IEEE, and Hui Li, Member, IEEE “Panda: Public Auditing for Shared Data with Efficient User Revocation in the Cloud” IEEE TRANSACTIONS ON SERVICES COMPUTING, VOL. 8, NO. 1, JANUARY/FEBRUARY 2015.

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