Swedish physicists prove quantum cryptography can be hacked
Source: Paul Hamaker
An experimental setup of the Franson interferometer. The setup consists of a source, 2 × 2 couplers (C), delay loops (ΔT), phase modulators ΦA and ΦB, and detectors (D).
Photo used with permission from Jogenfors et al. Sci. Adv. 2015;1:e1500793.
Quantum cryptography was thought to be an impervious method of data transfer that could prevent hacking of banking, government, and other sensitive data. Professor Jan-Åke Larsson at Linköping University's Division of Information Coding proved the theoretical possibility for hacking quantum cryptography and colleagues at Stockholm University developed a physical mechanism to prove that hacking the system is possible. The discovery was reported in the Dec. 18, 2015, edition of the journal Science Advances.
The purported invulnerability of quantum cryptography stems from the production of the same data containing photons from two sources sent in opposite directions and a test for noise that would indicate interference at both ends of the circuit using an interferometer. The researchers found that one of the photon sources could be replaced with a traditional light source allowing a hacker to open the code that protects data in quantum cryptography. The data can be read without detection because the hacker’s energy source never reaches the comparison gates.
No one can state for certain that anyone is using quantum cryptography. Some governments and a few of the world’s largest banks are reported to be using the systems because of the purported invulnerability. The researchers that found the flaw are seeking a means to restore the invulnerability of a system that promised to make data safety absolute. The proposed solutions involve simple countermeasures to a complete redesign of the present systems. The theoretical basis for the high level of data safety for quantum cryptography called Bell's inequality was developed in 1935 prior to the capacity to create photons of light that could be used to hack the system.
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