A method and system is provided by a Central-Entity, for identification and authorization of users over a communication network such as Internet. Central-Entity centralizes users personal and financial information in a secure environment in order to prevent the distribution of user's information in e-commerce. This information is then used to create digital identity for the users. The digital identity of each user is dynamic, non predictable and time dependable, because it is a combination of user name and a dynamic, non predictable and time dependable secure code that will be provided to the user for his identification.The user will provide his digital identity to an External-Entity such as merchant or service provider. The External-Entity is dependent on Central-Entity to identify the user based on the digital identity given by the user. The External-Entity forwards user's digital identity to the Central-Entity for identification and authentication of the user and the transaction.The identification and authentication system provided by the Central-Entity, determines whether the user is an authorized user by checking whether the digital identity provided by the user to the External-Entity, corresponds to the digital identity being held for the user by the authentication system. If they correspond, then the authentication system identifies the user as an authorized user, and sends an approval identification and authorization message to the External-Entity, otherwise the authentication system will not identify the user as an authorized user and sends a denial identification and authorization message to the External-Entity.