Embodiments for device pairing using optical codes are described. One embodiment is a host device with a memory and one or more processors configured to pair the host device with a wearable device. The paring involves generating and displaying an image including a first optical code, decoding decode a pairing advertisement from the wearable device, generating a second optical code, the second optical code comprising a host pairing advertisement code, and decoding a second pairing advertisement including the host pairing advertisement code. Additional embodiments involve, in response to the second pairing advertisement, establishing a communication channel between the host device and the wearable device, communicating keys between the host and wearable device, and using an application-level elliptic curve Diffie-Hellman (ECDH) exchange with the first key and the second key to establish a shared secret.