What do u mean by security ?

Security in software level .. i want confidentiality and sign that with digital signature .. and sent to the cloud where cloud check integrity of data and vice versa

would recommend you spend some time doing basic ground work before asking question. what do you want to sign ? what do you want to be confidential ? which data ? how is it different from basic SSL /TLS communication to a webserver ? is it the data being stored in server i.e data at rest? or data in transit ?

What do you want to secure in the cloud ? data, soft, etc.

Are we talking about securing cloud services ? storage ? compute? Data Bases ? ...

Can you give more details ...

To properly assess security in cloud technology you need to take a top-down risk assessment approach.  Look at the existing global standards that list security controls, like  CCM v.3.0.1(2014). It's freely downloadable.  Then study the control areas you are interested in simulating.  You can't model all of them -- there are too many.  And you will probably conclude that there is no silver bullet solution for cloud security.  Likely, any  cloud security issue you can think of is listed there with up to half a dozen references to security standards.  For some controls there are no standards, of course, e.g. things like mobile to cloud security, but that just shows you where an opportunity exists for useful research

You might want to first understand the security issues specific to clouds. For the basic ideas, here is my course on the overall security issues.

https://cis.uab.edu/class/cs643/643-743-fall-2014-2e/

Sir i want to implement similer problem attached in the paper .. i am not concerned about the index and searching part . i only want to implement security that is given in the paper .. please help to suggest me the procedure.thanks

I guess what you want to secure is your program and its related data, not the whole cloud platform, right ?

yes sir @peipei wang

The question of yours is too generic without any specifications and details. This is really not a way of asking questions or get even some decent help. Therefore I need to skip the part consisting of "I don’t know how to implement security in cloud computing" - because the simple answer is "the same as in noncloud environment with some specifics". The second part is little more understandable "also suggest me if i can use other simulator" - of course you can (that is the answer to your question. See? The question is just not well constructed) - but to be nice on you, I can give you some hints. I suppose you are starting with some research, so you want noncommercial solution – just dig deeper in these (opensource systems):

NetworkCloudSim (an extension of CloudSim as a simulation framework which supports generalized applications such)

EMUSIM (Emulation and Simulation; allows you Analytical modelling, Emulation, Benchmarking, Simulations and more)

CloudAnalys (derived from CloudSim; extends CloudSim with more capabilities and features)

GreenCloud (Basically a CloudSim fork that focuses on communication within the cloud)

@Anurag Mishra

First, You need to change and specify what the security means in your description. 

Second, the security implementation of program and its related data depends on the cloud computing system. Some system provide simple ways to do that, like authentication and data encryption. You may be able to create a sandbox in the cloud computing system as well, even hardware can support security model, such as Trusted computing.

If you are talking  about public cloud, you will let the Cloud Provider answer this question for you.  They are in charge of providing the security in the cloud infrastructure for you. However if you are talking about the Private Cloud, there are many things you can do.  You can install a Web application  Firewall  to protect" against the largest threat vector in  the cloud: web application attacks"( Alert Logic, Cloud Security report, 2014).

You can also use the NGFW,  the next generation firewalls to  secure your cloud environment.  These firewall will look at the behavior of software in your cloud to make sure they are acting like they are supposed to , otherwise they will be treated as a malicious ones.

Dr. Yves Delphin

Mr. Mishra, I think you have to dig out your problem statement first. Security is very wide area and you can build numerous models to perform simulation.