Authentication in the field of blockchain verification; Authentication, issuance and validation of digital certificates; Authentication of data in the field of marketing and advertising using blockchain technology; Computer security services in the nature of providing authentication, issuance, validation and revocation of digital certificates; Design and implementation of software and technology solutions for the purpose of product and document authentication and tracking, and brand monitoring and protection, to protect against counterfeiting, tampering, and diversion, and to ensure the integrity of genuine products and documents; Electronic document and e-mail authentication and time-stamping services using the time stamp of a national post office; Electronic signature verification services using technology to authenticate user identity; Providing electronic verification of on-line orders of digital content and generating electronic permission codes which then allow users to access said digital content; Providing user authentication services using blockchain technology for e-commerce transactions; Providing user authentication services using blockchain-based software technology for cryptocurrency transactions; User authentication services using blockchain technology for verification, authentification, certification of blockchain-based goods and services