# Introduction

loud Computing is an upcoming model which provides on-demand access to the resources provided on the network for different users accessing the service from the cloud in an efficient manner [1].The main advantages of cloud computing are providing increased scalability, providing cost effective services to users, customization of applications in an efficient manner, providing better storage space for users etc [2,12].

The different service models provided by the cloud are Software as a Service (Saas), Platform as a service (Paas), Infrastructure as a service (Iaas). In Saas model CSP(cloud service provider) provides the capability of controlling the applications running on the cloud. The benefits of this model are providing better administration, compatibility, collaboration among different users. In Paas model, CSP provides an infrastructure for deploying the applications which have been developed using programming languages that are specified. The benefits of this model are costs can be reduced and up gradation of different services can be done in an optimized manner. In Iaas model, CSP provides the necessary resources for deploying the consumers systems and applications. The benefits of this model are different administrative tasks can be automated in an optimized manner and better services based on policies [1, 3,13].

There are several deployment models which are emerged as cloud came into existence. A  The features of an ABE are listed below ? providing confidentiality for user's data.

? providing fine-grained access control for the user's data. 


# b) Homomorphic Encryption

It is promising research area and also cryptographic technique where complex mathematical computations are performed on encrypted data without decrypting them using user's private key. The different steps in performing Homomorphic encryption is summarized below where + and * denotes two algebraic operations.

? Let rÑ?"M be prime number chosen from M which is large and also taken as a secret key. ? Let p and q be two arbitrary integers with (p,q)<rÑ?"M.

? Encryption of p and q can be performed which is shown below. p'=p+(t1*r) where t1Ñ?"M is random large integer q'=q+(t2*r) where t2Ñ?"M is random large integer ? p'+q'=p+(t1*r)+q+(t2*r) and when performing decryption on mod r gives p+q(additive homomorphism) ? p'*q'=p+(t1*r)*q+(t2*r) and when performing decryption on mod r gives p*q(multiplicative homomorphism) iv.


# Example Explanation of Homomorphic Encryption

Given r=7,p=2,q=3,t1=4 and t2=5 p'=p+(t1*r)=2+(4*7)=30 q'=q+(t2*r)=3+(5*7)=38 (p'+q')mod r=(30+38)mod7=68mod 7=5(p+q) (p'*q') mod r= (30*38)mod7=1140mod 7=6(p*q)[16]. v. Advantages ? provides confidentiality, integrity and data protection.

? reduces the burden to cloud providers each time in decrypting the data in cloud.


# c) Cloud Computing Confidentiality Framework

The steps for the framework are summarized below ? Identify business goals and objectives.

? Perform impact analysis i.e., identification of system and processes in organization,  Secure Virtualization using Split Visor Architecture
?
Most Intel processors operate in two modes ? Virtual machine extension (VMX) root mode.

? VMX non root mode.

Split visor runs in VMX root mode where as Guest Visor and VM's runs in the VMX non root mode shown in the fig below [20].

Guest Visor VMC's (data structure maintaining the control information of VMX transition)is controlled by the split visor and VM's VMC's is controlled by Guest Visor.


# IV. Secure Virtualization using Security and Reliability Monitors

There are two features introduced for increasing security performance in virtualization technology using security and reliability monitoring units [19] a) VSEM b) VREM.

There are two more units(hypervisor security monitor(HSEM) and hypervisor reliability monitor(HREM) available in hypervisor level). The proposed architecture is shown in fig below [19]  It identifies attacks and malicious behavior of the virtual machine by helping HSEM. It is generally operated at two levels [19] ? In Level1, VSEM's monitor their own VM's. The proposed system identifies the VM as attacker if hypervisor recognizes the number of service requests more than specified threshold then VSEM notifies HSEM and switches to Level2[ 19] ? In Level 2, it monitors and captures the activity of each VM where hypervisor sets activity limits for types of activities until HSEM notifies that VM is not an attacker. HSEM gets the reliability status from VREM [19].


# b) VM Reliability Monitor(VREM)

Reliability requirements such as workload have been monitored and load balancer is being notified (within the hypervisor) that sends the workload status to HREM and decides to give VM more resources or not. The proposed HREM detects the overflow attacks if any when VM requests more resources than specified value [19].

i. Advantages ? The proposed architecture safeguards each virtual machine against all the possible attacks.  


# Conclusion

Cloud computing is an emerging technology which provides on demand-resources to customers. It provides high performance, scalable nature and low cost feasible solution to all the customers. Security is still major concern in cloud computing and it has to be provided with an utmost priority to the customers. Encryption techniques have been illustrated for securing the data hosted in cloud. This paper also illustrated techniques in improving virtualization security for cloud environment.
![cloud deployment model specifies the location for physical servers that have been deployed. The deployment models are private cloud, community cloud, Public cloud and hybrid cloud [1]. In private cloud, only one organization makes use of services in the cloud. In community cloud, organizations with similar requirements shared cloud infrastructure. In public cloud, computing resources are accessible to all the users utilizing cloud services owned by the organization. In hybrid cloud, different deployment models are combined with various cloud infrastructures. [3]. The different services provided by the cloud are shown in fig below.](image-2.png "")
1![Figure 1 : Cloud Services II.](image-3.png "Figure 1 :?")
![The essential characteristics of Homomorphic encryption are given below[14,16,17]. ? It is scalable cryptographic technique operating on any type of data hosted in the cloud. ? This scheme applies only to cloud providers. ? No authentication mechanism is needed. i. Homomorphism Let (A,+) and (B,*) be the two groups and there exists a relation f:A->B then f is group homomorphism in A and B if x,yÑ?" A such that f(x+y)=f(x)*f(y)[15]. ii. Applications ? Analyzing Biometric information? Medical Analysis ? Marketing Analysis ? Survey Analysis iii. Process of Homomorphic Encryption](image-4.png "")
![Data and system classification specifies what data needs to be secured and how valuable data and information systems are. ? Select security control selection of system along with data protection. ? Define the limitations in system taking into account trust, policy, system task and data protection dimensions ? Specify cloud security solutions (system, behavioral and hybrid) shown in fig below and make decision on cloud architecture [18]. Survey on Encryption and Improved Virtualization Security Techniques for Cloud Infrastructure](image-5.png "A")
2![Figure 2 : Cloud Computing Confidentiality Framework i. Advantages ? It provides authentication, confidentiality, integrity and data protection. ? It explains effective security controls for protecting data in private cloud environment III.](image-6.png "Figure 2 :")
4![Figure 4 : VSEM And VREM a) VM Security Monitor (VSEM)It identifies attacks and malicious behavior of the virtual machine by helping HSEM. It is generally operated at two levels[19] ? In Level1, VSEM's monitor their own VM's. The proposed system identifies the VM as attacker if hypervisor recognizes the number of service requests more than specified threshold then VSEM notifies HSEM and switches to Level2[ 19] ? In Level 2, it monitors and captures the activity of each VM where hypervisor sets activity limits for types of activities until HSEM notifies that VM is not an attacker. HSEM gets the reliability status from VREM[19].b) VM Reliability Monitor(VREM)Reliability requirements such as workload have been monitored and load balancer is being notified (within the hypervisor) that sends the workload status to HREM and decides to give VM more resources or not. The proposed HREM detects the overflow attacks if any when VM requests more resources than specified value[19].i. Advantages ? The proposed architecture safeguards each virtual machine against all the possible attacks.](image-7.png "Figure 4 :")


			© 2014 Global Journals Inc. (US)
		
		
			

				


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