Quantum cryptography (QC) or Quantum key distribution (QKD) are assumed hackproof but its implementations have vulnerabilities

Quantum computers could undermine almost all of the encryption protocols that we use today. Though quantum computers are still quite some way from being practical, usable machines, once they become so, we could be looking at a whole new world when it comes to online privacy — one in which even the strongest encryption can be broken.

 

By harnessing quantum super-positioning to represent multiple states simultaneously, quantum-based computers promise exponential leaps in performance over today’s traditional computers. Quantum computers shall bring power of massive parallel computing i.e. equivalent of supercomputer to a single chip. They shall also be invaluable in cryptology and rapid searches of unstructured databases. Quantum algorithms can break current security by reverse computing private keys may only take days or hours.

 

In 1994, Peter Shor of Bell Laboratories showed that quantum computers, a new technology leveraging the physical properties of matter and energy to perform calculations, can efficiently solve each of these problems, thereby rendering all public key cryptosystems based on such assumptions impotent. Thus a sufficiently powerful quantum computer will put many forms of modern communication—from key exchange to encryption to digital authentication—in peril.

 

There are two approaches. One is post-quantum cryptography, which is a new set of standard of classical cryptographic algorithms, and the other is quantum cryptography, which uses the properties of quantum mechanics to secure data. Both may have a place in the future of secure communication, but they work fundamentally differently.

 

Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. Quantum key distribution utilizes the unique properties of quantum mechanical systems to generate and distribute cryptographic keying material using special purpose technology. Quantum cryptography uses the same physics principles and similar technology to communicate over a dedicated communications link. Published theories suggest that physics allows QKD or QC to detect the presence of an eavesdropper, a feature not provided in standard cryptography.

 

 

One of the technology proposed for post quantum scenario is Quantum cryptography or Quantum key distribution  that is assumed hackproof. A unique aspect of quantum cryptography is that Heisenberg’s uncertainty principle ensures that if Eve attempts to intercept and measure Alice’s quantum transmissions, her activities must produce an irreversible change in the quantum states that are retransmitted to Bob. These changes will introduce an anomalously high error rate in the transmissions between Alice and Bob, allowing them to detect the attempted eavesdropping.

 

Toward its practical realization, tremendous progress has been made during the past decades. Metropolitan QKD networks have been successfully deployed and is going to be a continental scale. To provide information theoretically secure keys to real applications securely and seamlessly, an efficient key management system and application program interfaces have been developed.  For the QKD device itself, high-speed and stable operation is critical. By employing the ultrafast optical communication devices, high-speed QKD systems stably operated at GHz-clock frequency is realized in the installed fiber networks.

 

However there is an increasing understanding that the security of a QKD system relies not only on theoretical security proofs, but also on how closely the physical system matches the theoretical models and prevents attacks due to discrepancies. These side channel or hacking attacks exploit physical devices which do not necessarily behave precisely as the theory expects. As such there is a need for QKD systems to be demonstrated to provide security both in the theoretical and physical implementation.

 

For the QKD technology to be widely adopted, critical requirements are security certification, test-and-measurement method, security criteria for implementation, and countermeasures against the side channels. Moreover, those should be acceptable for non-experts.