CHAIN OF AUTHENTICATION USING PUBLIC KEY INFRASTRUCTURE

A method for sequential authentication based on chain of authentication using public key infrastructure (PKI) is provided. The method includes generating, by a user, a first private key and a first public key corresponding to each other; generating, by an nservice provider, an nprivate key and an npublic key corresponding to each other; transmitting, from the user to the nservice provider, a level n key; verifying, by the nservice provider, the level n key; generating, by the nservice provider, a level (n+1) key by concatenating the level n key and the npublic key signed with the nprivate key; and transmitting, by the nservice provider, the level (n+1) key to the user, where n is a natural number, and when n=1, the level 1 key is the first public key signed with the first private key.