strong user authentication
as defined in Regulation (EU) No 910/2014 of the European Parliament and of the Council of…, Article 3, point (51) (Definitions)
an authentication based on the use of at least two authentication factors from different categories of either knowledge, something only the user knows, possession, something only the user possesses or inherence, something the user is, that are independent, in that the breach of one does not compromise the reliability of the others, and is designed in such a way as to protect the confidentiality of the authentication data