Abstract: Disclosed is a set top box (STB) configured to work with a smart card (SC) wherein the STB is authenticated by an operator who provides the smart card to a user using a One Time Password (OTP). The OTP is generated by the SC and sent via the STB to the operator through a user mobile device operatively coupled with the STB. The operator verifies the sender based upon registered mobile number of the sender, decrypts the received OTP and uses the decrypted OTP to transmit STB specific control messages to the STB and facilitate registration of the SC. Thereafter the STB can receive and decrypt channel data being transmitted by the operator. The SC, STB and the user mobile device have secure communication amongst each other after authentication of each other. Data sent between the user mobile device and the operator is encrypted.