Method of operating payment device for selectively enabling payment function according to validity of host

A method of operating a payment device, the payment device including a near field communication controller (NFCC), payment circuitry configured to communicate with the NFCC, and at least one host application processor configured to communicate with the NFCC, the method comprising:

• generating, using the payment processing circuitry, unique data;
• sending, using the payment circuitry, the unique data to the NFCC;
• transmitting, using the NFCC, the unique data to the at least one host application processor;
• verifying, using the at least one host application processor, a validity status of a non-secure operating system being executed by the at least one host application processor, the verifying Induding determining whether the non-secure operating system has been modified;
• generating, using the at least one host application processor, signature data by signing verification data and the unique data, the verification data indicating the validity status of the at least on host application processor;
• sending, using the at least one host application processor, the signature data to the NFCC;
• transmitting, using the NFCC, the signature data to the payment circuitry;
• verifying, using the payment circuitry, the signature data;
• and
• selectively enabling, using the payment circuitry, payment function according to a result of the verifying the signature data.