Abstract: The invention concerns a method for preventing the loss of confidentiality of data electronically stored in the computer system comprising the following steps: analyzing the protocol and the data flow from and to data carriers and/or peripheral devices; forming a classification, particularly for differentiating between non-exchangeable and exchangeable data carriers; determining, according to the encountered classification, whether an encryption of the electronically stored data is required for preventing the loss of confidentiality of the data and, according to this determination; optionally supplementing the file system on an exchangeable data carrier with a cryptographic encryption and/or carrying out a cryptographic encryption of all or several of the blocks of the exchangeable data carrier.