A method of encoding data to prevent unauthorized reading and copying of information.

A method of encoding data to prevent unauthorized information reading, in which user information is converted into digital data, and digital data is recorded in a first data set and a second data set, comprising process the steps of dividing the digital data between the sets of first and second data, so that a part of the user information is contained only in the first data set, and another part of the user information is contained only in the second data set, and the relative proportion of the user information in the data sets is selected so that the information contained in any of the data sets is insufficient by itself to restore the complete user information contained in both data sets, characterized in that - the first data set is recorded in a first optical storage medium of a data carrier, - the second data set is recorded in a second, holographic storage medium of the data carrier, and the ratio of the user information in the data sets is that between the ratio of the data capacities of two media and the ratio of the speeds at which data are reproduced from the different media.