42 Certification of data via blockchain; authentication services; quality control and authentication services; user authentication services using blockchain technology; authentication services for computer security; computer programming of smart contracts on a blockchain; user authentication services using technology for e-commerce transactions; providing user authentication services using biometric hardware and software technology for e-commerce transactions; encryption, decryption and authentication of information, messages and data; design and development of single sign-on software; providing temporary use of on-line non-downloadable single sign-on software; advisory services relating to man-machine interfaces for computer software; computer technology consultancy; information technology consulting; providing information about the design and development of computer hardware and software; design of hardware for processing and distribution of multimedia contents.