The ethical principles which apply to everyday community life also apply to computing. It is unethical for any other person to violate these rights. Nobody else should use an ID without explicit permission from the owner.
All files belong to somebody.
They should be assumed to be private and confidential unless the owner has explicitly made them available to others. Messages sent to other users should always identify the sender. Network traffic should be considered private. Obscenities should not be sent by computer. Records relating to the use of computing and information resources are confidential.