Preserving Security and Privacy in cloud for Multi-Owner Data

Preserving Security and Privacy in cloud for Multi-Owner Data

1 K.Manikandan Assistant professor Sri Guru Institute of Technology

2 R.Malar Priya PG Scholar Adithya Institute of Technology

3 M.Murugesan PG Scholar Sri Guru Institute of Technology

Abstract

Cloud Computing could be used almost everywhere in todays society and provides numerous benefits to companies, government and individual users. One main concern of using the cloud is data privacy and security especially for users with sensitive data that would be detrimental to the client if it were stolen. Sharing data in a multi-owner manner while preserving data and identity privacy from an untrusted cloud is still a challenging issue, due to the frequent change of the membership. In this paper we use a digital group signature and broadcast encryption technique to provide a confidentiality, integrity, availability, accountability and privacy in multi-owner data.

Index Terms-cloud computing, dynamic group, access control, confidentiality, integrity, availability, accountability, privacy.

1. Introduction

   Cloud computing is about moving services, computation and/or datafor cost and business advantageoff-site to an internal or external, location- transparent, centralized facility or contractor. By making data available in the cloud, it can be

   more easily and ubiquitously accessed, often at much lower cost, increasing its value by enabling opportunities for enhanced collaboration, integration, and analysis on a shared common platform.

   A traditional data center of an organization is under

   complete control of that organization. The organization logically and physically protects the data it owns. For economical reasons, an organization may choose to use a public cloud for hosting its business services. In this case, the organization loses control of its data. This poses critical security risks that the organization needs to carefully consider and mitigate.

   Fig1.Cloud Framework

   The severity of risks depends on the sensitivity of the data stored in the cloud. Informal blogs twitter posts, public news, and newsgroup messages are examples of less sensitive data. The risk of hosting such data in the cloud is low. On the contrary, data such as health-related

   records, criminal records, credit history, and payroll information is highly sensitive business data. There are serious business and legal ramifications if such data is compromised. Therefore, the risk of hosting such data in the cloud is very high.

   Since data in the cloud is physically in control of the cloud provider, the foremost risk is that of ensuring confidentiality of the stored data. Encryption can be employed to ensure confidentiality. If the cloud provider uses multi-tenancy architecture, then separate encryption keys, one per cloud consumer, should be employed.

   Although cloud computing can offer small businesses significant cost-saving benefits namely, pay-as-you-go access to sophisticated software and powerful hardwarethe service does come with certain security risks. When evaluating potential providers of cloud-based services, you should keep these top six security concerns in mind.

   1. Secure data transfer

   2. Secure software interfaces

   3. Secure stored data

   4. User access control

   5. Data separation

   6. Multi authority Data

In Cloud Computing there are many threats which are avoiding the wide acceptance of cloud as explained above. The first problem with privacy is the disclosure of sensitive private information when exchanging data through the cloud service. And the sensitive private information includes: Personally identifiable information, Usage data, unique device identities and so on. The second problem is that people getting inappropriate or unauthorized access to personal data in the cloud by taking advantage of certain vulnerabilities, such as lack of access control enforcement, security holes and so on [6]. The third problem is that: because the feature of cloud computing is that it is a dynamic environment, in that service interactions can be created in a more dynamic way than traditional e-commerce scenarios. Services can potentially be aggregated and changed dynamically by service providers can change the

provisioning of services. In such scenarios, personal

Sensitive data may move around within an organization or across organizational boundaries, so adequate protection of this information must be maintained despite the changes.

There is lot of research going on in this field to ensure and provide data integrity in cloud storages. A lot of research discuss this problem and introduce many solutions to decrease the threat of the data privacy and integrity. Priya Metri and Geeta Sarote [4] introduce threat model to treat the privacy problem in the clouds. One of the threats in cloud computing is tampering with data in the cloud that interfere with the unauthorized modifications for the data, which lead to an effectiveness on processors, data storage and data flow. Then, they suggested different solutions technique for this threat. One of the solutions is using digital signature which will be used in our model.

1. DESIGNS:

   1. RSA Digital Signatures

      The notion of digital signatures goes back to the beginning of public-key cryptography. In their landmark paper "New Directions for Cryptography" (IEEE Transactions on Information Theory, 1976), Whitfield Diffie and Martin Hellman introduced the idea that someone could form a digital signature using public- key cryptography that anyone else could verify but which no one else could generate.

      While Diffie and Hellman provided a general model for digital signatures of any kind, the method developed by Rivest, Shamir, and Adleman in 1977, known as "RSA," has become the most proven and most popular, and achieved the widest adoption by standards bodies and in practice. Two other methods, discrete logarithm cryptography (including the Digital Signature Algorithm and the Diffie- Hellman key agreement method) and elliptic curve cryptography (see "Elliptic Curves and Cryptography," by Aleksandar

      Jurisic and Alfred J. Menezes, DDJ, April 1997) have also been embodied in several standards, but neither has yet been as widely adopted in practice as RSA.

      The RSA digital signature scheme applies the sender's private key to a message to generate a signature. The signature can then be verified by applying the corresponding public key to the message and the signature through the verification process, providing either a valid or invalid result. These two operations sign and verify comprise the RSA digital signature scheme.

      Any signature generated by the first operation will always verify correctly with the second operation if the corresponding public key is used. If the signature was generated differently or if the message was altered after being signed, then the chances of the second operation verifying correctly are extremely small; with typical parameters, the chance is roughly

      1 in 2160 or essentially zero. Although there are better ways to forge a signature than just guessing, the use of a sufficiently

      large key ensures security by making it computationally impractical to do so. For instance, it has been estimated to take thousands or even millions of years to break a given 1024-bit key (find the private key, given the public key), depending on the amount of computing power applied.

      Taking a close look at the signature generation portion of the process, the first step in generating an RSA signature is applying a cryptographic hash function to the message. The hash function is specifically designed to reduce a message of any length to a short number, called the "hash value" (typically 160 bits long), and to do it in a way such that two conditions are satisfied:

      It is difficult to find a message with a specific hash value.

      It is difficult to find two messages with the same hash value (an easier problem to solve).

      While many hash functions are available, only a few are commonly used in practice.

      Next, the hash value is converted into an integer called the "message representative,"

      with a length that is the same as the length of the RSA key being employed. This is done by applying a padding format to the resulting hash value or embedding the hash value to produce the message representative. In addition to its length-matching function, the padding format also provides additional security and is the primary differentiator among the various RSA signature schemes. The final step applies the RSA signature primitive to the message representative using the RSA private key to generate the signature.

   2. BROADCAST Encryption

A broadcast scheme allocates keys to users so that given a subset of, the center can broadcast messages to all users following which all members of have a common key. A broadcast scheme is called resilient to a set if for every subset that does not intersect with, no eavesdropper, that has all secrets associated with members of, can obtain knowledge of the secret common to. Knowledge here can have two different interpretations:

The secret common to has some a-priori distribution (usually the uniform distribution) and given the keys of and the message transmitted by the center the conditional distribution of the secret is not changed. The secret of is pseudo- random, i.e. no computationally bounded (by probabilistic polynomial time) eavesdropper can distinguish between the secret and a truly random string; even if the eavesdropper is provided with the keys of the coalition the secret of remains pseudorandom.

Advantage of the scheme is that if the adversary is in fact successful, after collecting 100,000 decryption devices, and if we have captured one of the adversary eavesdropping devices, all is not lost. It is still a relatively simple matter to disable all adversary de vices by disabling one group of 1000 users, splitting these users amongst other groups; the adversary effort has been in vain.

1. PERFORMANCE

   RSA Digital Signature is more secure than DSA and Elliptic curve Signature

   algorithm. Broadcast Encryption is more efficient than Multicast and unicast Transmission.

   In fig2 X axis represent the encryption technique and Y axis represent the efficiency.

   100

   80

   60

   40

   20

   0

   100

   80

   60

   40

   20

   0

   Fig2. Performance analysis

2. CONCLUSION

   In this paper, we use a RSA digital signature and broadcast encryption to preserve confidentiality, integrity, availability, accountability and privacy in a multi-owner data.

   A user is able to share data with others in the group without revealing identity privacy to the cloud. Additionally, it supports efficient user revocation and new user joining.

   More specially, efficient user revocation can be achieved through a public revocation list without updating the private keys

   of the remaining users, and new users can directly decrypt files stored in the cloud before their participation. Moreover, the storage overhead and the encryption computation cost are constant.

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