A method for operating an Internet site providing encrypted contents is provided, and includes the steps of (a) a site server determining whether or not a customer accessing the site is a registered subscriber; (b) automatically generating a customer-unique encryption key, establishing the site using environment information from the customer computer, and logging-in through a main page in which the customer can select desired contents, when the customer accessing the site is a non-subscriber in the step (a) and the non-subscriber customer requests to register as a subscriber by providing his personal information to the site server; (c) logging in through the main page when, in the step (a), it is determined that the customer accessing the site is a subscriber, using customer information provided by the customer computer; and (d) providing the selected content to the customer computer, after encrypting the content with the customer-unique encryption key.