Abstract: The invention relates to a method for supporting the blocking of credit or bank cards of a card user, and a blocking server, a device and a bank server to execute the method. A card-individual blocking code is stored in a storage medium. Upon a control command from the card user, the blocking code is read from the storage medium and a card-individual blocking code is sent over a communications network to a central blocking server. The received blocking code is verified by the central blocking server. Upon positive verification, the blocking server prompts the blocking of the credit or bank card related to the blocking code.

Abstract: The present invention relates to the automated carrying out of transactions or conclusions of contracts between contracting parties (A, B) in a communications network, such as for example the internet I. In particular there are described the necessary digital documents (D) for such an automated procedure, data processing devices (C) for assuming witness functions, data processing devices (P) for assuming guarantee functions, and computer software to be installed on corresponding computers for the carrying out of such transactions and conclusions of contracts.