Abstract: There is provided a device for transmitting a push-to-talk message. The device includes a communication interface, and an operation processor that transmits a first segment group of the PTT message among segments of the PTT message to first to n-th PTT devices through the communication interface; transmits a heartbeat signal to the first to n-th PTT devices through the communication interface; receives an i-th response signal to the heartbeat signal from an i-th PTT device through the communication interface; allocates, based on the i-th response signal, the i-th PTT device to a first group to which a second segment group of the PTT message is transmitted without any conversion or a second group to which data obtained by converting the second segment group is transmitted; and transmits the second segment group to the first group and the data to the second group through the communication interface.

Abstract: A method includes (a) receiving i-th data among first to n-th data transmitted in a multicast manner from a firmware providing apparatus, (b) acquiring partitioning information thereof, a MAC chaining value, length information, i-th firmware data, and MAC from the i-th data, (c) authenticating the MAC chaining value of the i-th firmware data, the length information, and the i-th firmware data by comparing a MAC of the i-th firmware data with a value computed by a first MAC generation algorithm, which uses the MAC chaining value of the i-th firmware data, the length information, and the i-th firmware data as a relevant input; (d) authenticating the order of the i-th firmware data by using the MAC chaining value of the i-th firmware data and a second MAC generation algorithm; and (e) obtaining the firmware by combining a first to an n-th firmware data obtained by executing (a) to (d).