The article deals with the problem of knowledge erosion as the result of data and information explosive growth. The conception of knowledge and knowledge core as a system of established and accepted scientific ("textbook") knowledge necessary to be transferred for sustainable social development is presented. The way of protecting knowledge core from destruction and unauthorized change is proposed with the use of Unified Electronic Educational Environment (UEEE) based on a set of learning objects constituting the Unified Bank of Learning Objects. Permitted blockchain algorithm as a basic means of protecting Unified Bank of Learning Objects is considered.