Researchers at the University of Rochester have moved beyond the theoretical in demonstrating that an unbreakable encrypted message can be sent with a key that's far shorter than the message -- the first time that has ever been done.
Until now, unbreakable encrypted messages were transmitted via a system envisioned by American mathematician Claude Shannon, considered the "father of information theory." Shannon combined his knowledge of algebra and electrical circuitry to come up with a binary system of transmitting messages that are secure, under three conditions: the key is random, used only once, and is at least as long as the message itself.
The findings by Daniel Lum, a graduate student in physics, and John Howell, a professor of physics, have been published in the journal Physical Review A.
"Daniel's research amounts to an important step forward, not just for encryption, but for the field of quantum data locking," said Howell.
Quantum data locking is a method of encryption advanced by Seth Lloyd, a professor of quantum information at Massachusetts Institute of Technology, that uses photons -- the smallest particles associated with light -- to carry a message. Quantum data locking was thought to have limitations for securely encrypting messages, but Lloyd figured out how to make additional assumptions -- namely those involving the boundary between light and matter--to make it a more secure method of sending data.
While a binary system allows for only an on or off position with each bit of information, photon waves can be altered in many more ways: the angle of tilt can be changed, the wavelength can be made longer or shorter, and the size of the amplitude can be modified. Since a photon has more variables -- and there are fundamental uncertainties when it comes to quantum measurements -- the quantum key for encrypting and deciphering a message can be shorter that the message itself.
Lloyd's system remained theoretical until this year, when Lum and his team developed a device -- a quantum enigma machine -- that would put the theory into practice. The device takes its name from the encryption machine used by Germany during World War II, which employed a coding method that the British and Polish intelligence agencies were secretly able to crack.
Let's assume that Alice wants to send an encrypted message to Bob. She uses the machine to generate photons that travel through free space and into a spatial light modulator (SLM) that alters the properties of the individual photons (e.g. amplitude, tilt) to properly encode the message into flat but tilted wavefronts that can be focused to unique points dictated by the tilt. But the SLM does one more thing: it distorts the shapes of the photons into random patterns, such that the wavefront is no longer flat which means it no longer has a well-defined focus. Alice and Bob both know the keys which identify the implemented scrambling operations, so Bob is able to use his own SLM to flatten the wavefront, re-focus the photons, and translate the altered properties into the distinct elements of the message.
Along with modifying the shape of the photons, Lum and the team made use of the uncertainty principle, which states that the more we know about one property of a particle, the less we know about another of its properties. Because of that, the researchers were able to securely lock in six bits of classical information using only one bit of an encryption key--an operation called data locking.
"While our device is not 100 percent secure, due to photon loss," said Lum, "it does show that data locking in message encryption is far more than a theory."
The ultimate goal of the quantum enigma machine is to prevent a third party -- for example, someone named Eve -- from intercepting and deciphering the message. A crucial principle of quantum theory is that the mere act of measuring a quantum system changes the system. As a result, Eve has only one shot at obtaining and translating the encrypted message -- something that is virtually impossible, given the nearly limitless number of patterns that exist for each photon.
The paper by Lum and Howell was one of two papers published simultaneously on the same topic. The other paper, "Quantum data locking," was from a team led by Chinese physicist Jian-Wei Pan.
"It's highly unlikely that our free-space implementation will be useful through atmospheric conditions," said Lum. "Instead, we have identified the use of optic fiber as a more practical route for data locking, a path Pan's group actually started with. Regardless, the field is still in its infancy with a great deal more research needed."
Peter Iglinski | EurekAlert!
APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie
First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences