Abstract: A system and method for authentication of a user using “lightweight” identities. The system and method provides for establishment of user credentials for a particular electronic mail address by an identity server through the recordation of a mail token and private token after receiving a request for credentials from the user. The identity server sends a private token to the user and sends a verification message to the user containing a specific link to the identity server for verification of the user along with the mail token, and then can verify the user by confirming that a mail token and private token recorded by the identity server match a mail token and a private token received from the user. After the verification process is successful, the identity server issues credentials that consist of a certificate either with or without a private key to the user which serves as an authenticated, unique, lightweight identity that a user can assume to access various services.