Authenticated semi-quantum key distribution without entanglement

One important challenge of quantum key distribution is to preserve its unconditional security when a scheme is implemented. In semi-quantum key distribution (SQKD), one of the parties is only able to perform classical operations, thus alleviating the cost of its implementation. Authenticated SQKD (ASQKD) ensures also better security than SQKD against attacks aiming at the identity of the parties. In this regard, Li et al. have proposed a new ASQKD scheme that ensures better efficiency than the first proposed ASQKD scheme of Yu et al. However, both schemes present loopholes in their security. This study presents a new ASQKD without using entanglement, able to achieve higher security than the schemes of Yu et al. and Li et al. Our scheme is also simpler and demands less advanced quantum devices than ASQKD schemes using entanglement.