In a key pair management method for use in an image forming device, one or more key pairs which are usable for secure communication between the image forming device and an external device are stored into a first area of a memory. A key pair required for the secure communication with the external device is received from the first area of the memory. After the key pair is received from the first area of the memory, the key pair required for the secure communication with the external device is generated in an asynchronous mode and stored into the first area of the memory again. The secure communication between the image forming device and the external device is performed using the key pair received from the first area of the memory.