At the moment, the exchange of data via insecure communication channels is the most vulnerable to information systems that store a large amount of data, the partial loss or substitution of which can lead to irreversible consequences. For this reason, in order to ensure security, the task is to use such methods and means that allow to verify the authenticity of the user's belonging to this system and, if successful, give access to information.
In this paper are reviewed authentication methods that can be used depending on the needs of the systems, their vulnerabilities and recommend solutions to use. Authentication is process of granting a user access to an information system. There are three main types of authentication mechanisms:
1. The user knows some unified information (password entry);
2. The user has a unified information storage (smart card, token);
3. The user himself is an integral part of the authentication (biometric).
Each authentication mechanism functions differently and has their strengths and weakness.