Credit: VectorMine/Shutterstock
Topics: Computer Science, Cryptography, Cybersecurity, NIST, Quantum Computer, Quantum Mechanics
Note: As a Communications-Computer Systems Officer in the US Air Force, I was once responsible for Technical Control, Computer Maintenance, and Crypto-Teletype (not that anyone uses a teletype anymore – I hope not!). I also beta-tested DARPANET at Bergstrom Air Force Base, which you are now using as the World Wide Web. It’s humbling to see how things have evolved from Zenith computers, behemoths that required a van the size of a one-car garage as their mainframe, now compacted in our hip pockets or laptops.
What is cryptography?
For centuries, royal figures, government officials, and military officers — along with spies and assassins — have used secret codes to protect their confidential messages. These individuals were performing early versions of cryptography — employing mathematical techniques to protect the security of information.
These secret codes, known as ciphers, could be as simple as taking a message and shifting each letter of the alphabet by a certain number of positions so that A became D, B became E, etc. But cryptography has evolved greatly since these earliest examples.
Nowadays, digital devices such as computers routinely carry out mathematical operations to scramble information in highly complex ways. In addition to being much more technologically advanced, modern cryptography frequently includes authentication — verifying that both the sender and the receiver of information really are who they say they are.
What is quantum cryptography?
Quantum cryptography is a set of methods that uses the quirky — but well-understood — rules of quantum mechanics to securely encrypt, transmit, and decode information. Quantum cryptography employs quantum devices, such as sensors capable of recording individual particles of light (photons), to protect data from an adversarial attack. Although technically challenging, quantum cryptography promises advantages over classical, nonquantum cryptographic systems. For instance, the quantum approach has the potential to better detect and thwart eavesdroppers who try to intercept data.
One early example of a quantum cryptographic protocol, known as quantum key distribution (QKD), uses a string of computer bits or characters (called an encryption key) shared by two trusted partners to scramble and unscramble data. Although the encryption key itself is not quantum, it is transmitted using quantum particles — photons. In 2004, Austrian scientists employed QKD to establish a secure connection for the transfer of funds from a bank to Vienna City Hall.
QKD systems, however, still have technological and theoretical loopholes, some of which could make it possible for eavesdroppers to intercept and decode messages. Because of these current limitations, the National Security Agency does not recommend using QKD for national security systems.
Physics and Nano 