how to set administrator permission (ask computer Password) before copy or cut any file to external devices like pendrive/cd/dvd
What is it you’re trying to achieve? Prevent a logged-in user from copying any data off the computer? If so, the best approach would be to require superuser privileges either for mounting any external drives in the first place, or for mounting them writeable. If you’re trying to prevent others from accessing the data in the first place, then encryption is the way to go.
asking password or need super user permission to copy,cut file form system to pendrive
Once a person is logged into an account in Linux, access to files already depends on the account’s permissions. Pendrives will be mounted automatically in most cases unless they are encrypted (although I suspect there is a way to change that behaviour in Gnome). If the user 's account has permission to read a file – they can copy it. If you set file and folder permissions to require root privileges only … the user can only access or copy those files when they navigate as root(administrator). Its simple – no need for pop-ups for copying files
encryption of file may make the system slow while booting
Bro … you have to choose between Security and boot speed in this case. A few seconds or minutes extra won’t hurt.