New protocols for quantum key distribution with explicit upper and lower bound on secret key rate

We present two new schemes for quantum key distribution (QKD) that neither require entanglement nor an ideal single-photon source, making them implementable with commercially available single-photon sources. These protocols are shown to be secure against multiple attacks, including intercept-resend and a class of collective attacks. We derive bounds on the key rate and demonstrate that a specific type of classical pre-processing can increase the tolerable error limit. A trade-off between quantum resources and information revealed to an eavesdropper (Eve) is observed, with higher efficiency achievable through the use of additional quantum resources. Specifically, our proposed protocols outperform the SARG04 protocol in terms of efficiency at the cost of more quantum resources.