Brugerterminal for dataudtag og anordninger til at regulere et sådant udtag

摘要

A system for controlling and accounting for retrieval of data from a CD-ROM memory containing encrypted data files from which retrieval must be authorized. The system includes an authorization and key distribution terminal and a plurality of customer data retrieval terminals having such memories (37) loaded therein. The authorization terminal authorizes retrieval of data by authorized customer terminals by providing to the authorized customer terminals an encryption key (13) for enabling retrieval of the data and an authenticated credit signal (14) for use in limiting the amount of data to be retrieved from the files. The encryption key is encrypted for communication to the customer terminals in unique unit keys (42) that are stored (24) in the respective customer terminals. The customer terminal limits (22) the amount of data retrieved from the files in accordance with the credit signal; records (23) the amount of data retrieved from the files; and provides to the authorization terminal an anthenticated report (62) of the recorded amount of data retrieved from said files. The memory (37) includes data files of different data vendors; and the customer terminal separately records (23) the retrieval of data from the files of the different vendors.