The article is devoted to the method of authentication of laptops based on the correlation analysis of their internal electric fluctuations. The following results were obtained: the authentication of each laptop can be carried out uniquely by its internal electrical fluctuation; uniqueness of authentication is provided by the invariants of the autocorrelation function of fluctuations; the authentication sign is based on an analysis of the shape of the graph of the autocorrelation function. The authentication algorithm is presented.