I will talk about the use of brain activity data in authentication systems and demonstrate how personal data can be extracted from electroencephalogram (EEG). My presentation will begin with a brief introduction to neurotechnologies. I will tell you about methods for registering brain activity, data processing and its application. I will describe in detail the construction of verification systems with EEG as a biometric parameter. I will prove the concept of extracting personal data from EEG using the example of obtaining the pin code of a bank card. I will also talk about attacks on neurointerfaces and the need to protect brain activity data.