Abstract: The invention relates to a method and a communication system for releasing a data processing unit used for processing project data of a selected project. In order to obtain project-related release of a data processing unit (90), a client requests a user right for the data processing unit (90) used for processing the project data that is part of a predetermined project. A first signature (I) is verified as to the correctness thereof. The data processing unit (90) is released to process the project data that is part of the selected project only if the verification process has established that the first signature (I) is correct.

Abstract: A method for financing multimedia content through advertising includes playing back advertising blocks between uses of the content so to finance use of the content by the advertising. Code elements of a key are embedded in predefined locations in the advertising blocks, the key being configured for decryption of the content that follows. The embedded code elements are scanned and collected during the playback of the advertising blocks. The code elements are linked schematically to form the key. The content is encrypted using the key so that a use of the content depends on at least one of a subset of the code elements determined by the advertiser and the key.

Abstract: The invention relates to a method and a communication system for releasing a data processing unit used for processing project data of a selected project. In order to obtain project-related release of a data processing unit (90), a client requests a user right for the data processing unit (90) used for processing the project data that is part of a predetermined project. A first signature (I) is verified as to the correctness thereof. The data processing unit (90) is released to process the project data that is part of the selected project only if the verification process has established that the first signature (I) is correct.

Abstract: Advertisers who finance the showing of useful data have an interest in ensuring that mixed-in sequences of advertisements are really shown and not skipped by means of intermediate recording. In order to make the showing of the useful data dependent on the reproduction of the sequences of advertisements, code elements of a key are embedded at certain points in the sequences of advertisements. While the sequences of advertisements are being played back, these code elements are scanned and collected, then combined to produce a complete key. If the subsequent useful data are encrypted with this key, their reproduction is dependent on the key. This method of making the reproduction of the useful data dependent on the reproduction of the sequences of advertisements can be used for known advertising-financed free TV, known and initialized recording methods and new advertising-financed multimedia content and products.