# cryptography quantum

Quantum cryptography is a field that explores the use of quantum mechanics to create secure communication protocols. Unlike classical cryptography, which relies on mathematical assumptions about the difficulty of certain computational problems, quantum cryptography leverages the fundamental principles of quantum mechanics to achieve a higher level of security.

Here are some key concepts and methods in quantum cryptography:

**Quantum Key Distribution (QKD):**One of the most well-known applications of quantum cryptography is Quantum Key Distribution. QKD allows two parties to generate a shared secret key over a potentially insecure communication channel. The key distribution process is secure because any attempt to eavesdrop on the quantum communication would disturb the quantum states, and this disturbance can be detected.**Quantum Entanglement:**Quantum entanglement is a phenomenon where two or more particles become correlated in such a way that the state of one particle cannot be described independently of the state of the other(s). This property is used in QKD to ensure the security of the key distribution process.**Quantum Superposition:**Quantum bits, or qubits, can exist in multiple states simultaneously through a phenomenon called superposition. This property allows quantum systems to perform certain types of computations more efficiently than classical systems.**Quantum Cryptographic Protocols:****BBM92 Protocol:**Proposed by Charles Bennett and Gilles Brassard in 1992, this was one of the first quantum key distribution protocols.**E91 Protocol:**Developed by Artur Ekert in 1991, this protocol uses entanglement to ensure secure key exchange.**BB84 Protocol:**Proposed by Bennett and Brassard in 1984, this is another early QKD protocol that uses the polarization states of photons for key distribution.

**Post-Quantum Cryptography:**While quantum cryptography leverages the principles of quantum mechanics to provide security, it's also essential to consider the potential threat posed by quantum computers to classical cryptographic systems. Quantum computers have the capability to solve certain mathematical problems much faster than classical computers, potentially compromising widely used encryption algorithms. As a result, researchers are working on developing post-quantum cryptographic algorithms that would remain secure even in the era of quantum computing.