A secure authentication method for performing secure authentication of a user by an authentication system comprising a first communication terminal, a second communication terminal storing a plurality of encrypted code tables wherein each encrypted code table is distinguished for each user and also by endpoint information and, comprising a security keypad, a service server and a security server in interoperation with each other, the secure authentication method being characterized in that it comprises: receiving, by the service server, a service request from the first communication terminal; in response to the request, identifying, by the service server, identification information of a user and the endpoint information where authentication information is used and transmitting a notification request message including the identification information of a user and the endpoint information to the security server; identifying, by the security server, the identification information of a user and the endpoint information included in the notification request message; extracting, by the security server, a decryption key based on the received identification information of a user and the received endpoint information; transmitting, by the security server, a notification message including the endpoint information and the extracted decryption key to the second communication terminal; extracting, by the second communication terminal, an encrypted code table from the plurality of encrypted code tables based on the endpoint information received from the security server, wherein each of the plurality of encrypted code tables records codes, wherein the recorded codes are generated such that the recorded codes are mapped to key buttons of the security keypad randomly; decrypting, by the second communication terminal, the extracted encrypted code table using the decryption key received from the security server; outputting, by the second communication terminal, the security keypad to a screen, and when at least one input value is received through the security keypad, identifying each code mapped to the received at least one input value in the decrypted code table; generating, by the second communication terminal, authentication information consisting of a combination of each identified code, and transmitting the authentication information to the service server; and authenticating, by the service server, the first communication terminal based on the authentication information received from the second communication terminal. receiving, by the service server, a service request from the first communication terminal; in response to the request, identifying, by the service server, identification information of a user and the endpoint information where authentication information is used and transmitting a notification request message including the identification information of a user and the endpoint information to the security server; identifying, by the security server, the identification information of a user and the endpoint information included in the notification request message; extracting, by the security server, a decryption key based on the received identification information of a user and the received endpoint information; transmitting, by the security server, a notification message including the endpoint information and the extracted decryption key to the second communication terminal; extracting, by the second communication terminal, an encrypted code table from the plurality of encrypted code tables based on the endpoint information received from the security server, wherein each of the plurality of encrypted code tables records codes, wherein the recorded codes are generated such that the recorded codes are mapped to key buttons of the security keypad randomly; decrypting, by the second communication terminal, the extracted encrypted code table using the decryption key received from the security server; outputting, by the second communication terminal, the security keypad to a screen, and when at least one input value is received through the security keypad, identifying each code mapped to the received at least one input value in the decrypted code table; generating, by the second communication terminal, authentication information consisting of a combination of each identified code, and transmitting the authentication information to the service server; and authenticating, by the service server, the first communication terminal based on the authentication information received from the second communication terminal.