CybersecurityMaking mobile transactions more secure with a quantum key system

Published 17 March 2017

With the growing popularity of mobile phone apps to pay for purchases at cash registers and gas pumps, users would like to know their personal financial information is safe from cyber-attacks. For the first time, researchers have demonstrated a prototype device that can send unbreakable secret keys from a handheld device to a terminal. If integrated into a cell phone, for example, the device could allow secure links to near-field communications mobile payment systems and indoor Wi-Fi networks. It also could improve the security of ATMs and help prevent ATM skimming attacks, which are estimated to cost the industry more than $2 billion annually.

Entangled photons in confined space // Source: theconversation.com

With the growing popularity of mobile phone apps to pay for purchases at cash registers and gas pumps, users would like to know their personal financial information is safe from cyber-attacks. For the first time, researchers have demonstrated a prototype device that can send unbreakable secret keys from a handheld device to a terminal.

OSA says that in The Optical Society’s journal Optical Express, researchers lay out a scheme for transmitting quantum keys at a high enough data rate to ensure data security while compensating for the inevitable movement of the human hand. Their prototype system uses ultra-fast LEDs and moveable mirrors to send a secret key at a rate of more than 30 kilobytes per second over a distance of 0.5 meters.

“The idea is that this gadget would be a mobile object that talks to something that is fixed,” said Iris Choi of Oxford University, one of the paper’s authors. If integrated into a cell phone, for example, the device could allow secure links to near-field communications mobile payment systems and indoor Wi-Fi networks. It also could improve the security of ATMs and help prevent ATM skimming attacks, which are estimated to cost the industry more than $2 billion annually.

Keys made from light
The technology is a quantum key distribution system. Quantum key distribution relies on characteristics of a single photon to provide a bit — a 1 or a 0 — to build up a cryptographic key that can encrypt and decrypt information. Quantum keys are considered secure because if someone intercepts the quantum bits and then passes them on, the very act of measuring them will alter them.

“When an eavesdropper attempts to tap into the channel, it will change the content of the key,” Choi said. “We’re not saying this technology can prevent being eavesdropped on, but if you do eavesdrop, we know you’re there.”

The system contains six resonant-cavity LEDs, which provide overlapping spectra of light. Each of the six is filtered into a different polarization, split into pairs to represent 1s and 0s — horizontal or vertical, diagonal or anti-diagonal, circular left or circular right. The circularly polarized LEDs provide the bits for the key, while the other pairs are used to measure the security of the channel and provide error correction. Every four nanoseconds, one of the channels produces a one-nanosecond pulse in a random pattern. On the other end, six polarized receivers pick up the