45 Authentication, issuance and validation of digital certificates; installation of client certificates on client computers to enable mutual authentication with servers; distribution, installation, maintenance and termination of digital certificates; Computer security services in the nature of providing an internet trust center, namely, computer security assurance and administration of digital keys and digital certificates; Identification verification services, namely, providing authentication of personal identification information using a digital certificate for access to a VPN via a mobile telephone; identification validation services, namely, via mobile phone authentication ; Providing user authentication services in e-commerce transactions; User authentication services, namely, providing a secure one-time password instantaneously and completely offline, using a mobile phone