Today, the latest example of cloud computing is Web 2.0;Google, Yahoo, Microsoft, and other service providers now offer browserbased enterprise service applications (such as webmail and remote data backup). Now that cloud computing has emerged as a viable and readily available platform, many users from disparate backgrounds (for example, financial institutions, educators, or cybercriminals) are sharing virtual machines to perform their daily activities. This environment re-quires an implicit level of trust aswell as an explicit level of vigilance to ensure success