What are the security requirements and challenges of Grid and Cloud Computing? Solution security issues: A. Policies: 1) Inside Threats: good supervision should be done for having trusted employees . 2) Access Control:Digital signature can be implemented for access control. 3) System Portability: The problem of vendor lock-in should be handled . B. Software Security: 1) Virtualization technology: up to date version of virtualization product should be installed for the security reasons. 2) Host Operating System:should be up to date and secure from hackers 3) Guest Operating System: should be up to date and secure from hackers 4) Data Encryption:should be done on all the data for its safety. C)Physical security: 1) Backup:Either a backup plan should be provided automatically for each customer, or they can use the plans provided elsewhere in the cloud. 2) Server Location:It should be at appropriate place. Room should have adequate space and isolated. A Cooling System and Fire Suppression System should be installed there. 3) Firewall: Cloud Computing service providers should provide a complete firewall solution to their clients. Challenges: A)No clear standard:Grid computing uses various standards, but all grids are not use same standards. Example all grid operating system such as Linux, Apache,and My SQL are using WSRF, WWW, SOAP and XML standards. B)Distributed computing Vs Grid computing: Grid computing involves dynamic virtual organisation, resource sharing and peer to peer computing. The Grid intends to make access to computing power, scientific data repositories and experimental facilities as easy as the Web makes access to information. Same all facilities provide the grid computing. So it is a challenge for grid computing. C)Lack of grid enabled software: The software, which are enabled the grid computing are less, It has limited software on Grid. Much software has not copyright issues and source code of licence. It is need for more company developing grid-enabled version, need more developers on grid development and need to develop open source software. D)Sharing Resources between Various types of Services:Grid used for sharing resource from various sites and grid hosts. It handles a massive amount of data as a grid platform. A lot of sites and multiple servers gathered there it is so complex infrastructure. It provides difficulty for hardware resource sharing within virtual organisation..