The presented text deals with designing of a multilingual application and its following implementation in the C++ language. The application encrypts disk volumes with Microsoft Windows system using symmetric cryptography and password authentication, where the password security strength is verified. Securing the sensitive data is one of the important security goals in area of information technology. The symmetric cryptography uses the same key for both the encryption and the decryption and due to its speed it is suitable for the data storage encryption. For the higher security it is possible to encrypt a whole disk volume with sensitive data.