Quantum Key Distribution - Introduction, Protocols and Current Challenges

As quantum computing threatens the foundations of classical asymmetric cryptography, Quan-tum Key Distribution (QKD) has been heralded as a vital alternative for unconditional security.This article reviews the theoretical framework of QKD, compares dominant protocols such asBB84 and E91, and evaluates the hurdles limiting their widespread viability. Key implemen-tation challenges, ranging from transmission distance limits to hardware-specific side-channelattacks, are discussed. The review highlights that the future of the Quantum Internet dependsnot only on theoretical protocols but on overcoming the practical security and infrastructuregaps currently preventing widespread adoption Author Info: ORCID: https://orcid.org/0009-0001-5132-0050 LinkedIN: https://www.linkedin.com/in/asthaashray