Techniques are disclosed relating to the secure communication of devices. In one embodiment, a first device is configured to perform a pairing operation with a second device to establish a secure communication link between the first device and the second device. The pairing operation includes receiving firmware from the second device to be executed by the first device during communication over the secure communication link, and in response to a successful verification of the firmware, establishing a shared encryption key to be used by the first and second devices during the communication. In some embodiments, the pairing operation includes receiving a digital signature created from a hash value of the firmware and a public key of the second device, and verifying the firmware by extracting the hash value from the digital signature and comparing the extracted hash value with a hash value of the received firmware.