  Device-independent quantum key distribution protocols allow two honest users
to establish a secret key with minimal levels of trust on the provider, as
security is proven without any assumption on the inner working of the devices
used for the distribution. Unfortunately, the implementation of these protocols
is challenging, as it requires the observation of a large Bell-inequality
violation between the two distant users. Here, we introduce novel photonic
protocols for device-independent quantum key distribution exploiting
single-photon sources and heralding-type architectures. The heralding process
is designed so that transmission losses become irrelevant for security. We then
show how the use of single-photon sources for entanglement distribution in
these architectures, instead of standard entangled-pair generation schemes,
provides significant improvements on the attainable key rates and distances
over previous proposals. Given the current progress in single-photon sources,
our work opens up a promising avenue for device-independent quantum key
distribution implementations.
