FUTURE METHODS OF ENCRYPTION
Read the following words and word combinations and use them for understanding and translation of the text:
eavesdropper - перехватчик
to harness — приспособить, поставить на службу
spin - вращение
binary code – двоичный код
coherent - понятный
to accomplish - выполнять
to discard - отбрасывать
discrepancy - несоответствие
parity check — контроль четности
to bounce - отскакивать
spooky — жуткий, зловещий
entanglement - переплетение
fiber optic cable – оптоволоконный кабель
Quantum Cryptology
One of the great challenges of cryptology is to keep unwanted parties – or eavesdroppers - from learning of sensitive information. Quantum physics has provided a way around this problem. By harnessing the unpredictable nature of matter at the quantum level, physicists have figured out a way to exchange information on secret keys.
Quantum cryptography uses photons to transmit a key. Once the key is transmitted, coding and encoding using the normal secret-key method can take place. But how does a photon become a key? How do you attach information to a photon's spin?
This is where binary code comes into play. Each type of a photon's spin represents one piece of information - usually a 1 or a 0, for binary code. This code uses strings of 1s and 0s to create a coherent message. So a binary code can be assigned to each photon. Alice can send her photons through randomly chosen filters and record the polarization of each photon. She will then know what photon polarizations Bob should receive. Bob has no idea what filter to use for each photon, he's guessing for each one. After the entire transmission, Bob and Alice have a non-encrypted discussion about the transmission.
The reason this conversation can be public is because of the way it's carried out. Bob calls Alice and tells her which filter he used for each photon, and she tells him whether it was the correct or incorrect filter to use. Since Bob isn't saying what his measurements are - only the type of filter he used - a third party listening in on their conversation can't determine what the actual photon sequence is.
In modern cryptology, Eve (E – an eavesdropper) can passively intercept Alice and Bob's encrypted message - she can get her hands on the encrypted message and work to decode it without Bob and Alice knowing she has their message. Eve can accomplish this in different ways, such as wiretapping Bob or Alice's phone or reading their secure e-mails.
Quantum cryptology is the first cryptology that safeguards against passive interception. Here's an example. If Alice sends Bob a series of polarized photons, and Eve has set up a filter of her own to intercept the photons, Eve is in the same boat as Bob: Neither has any idea what the polarizations of the photons Alice sent are. Like Bob, Eve can only guess which filter orientation she should use to measure the photons.
After Eve has measured the photons by randomly selecting filters to determine their spin, she will pass them down the line to Bob. She does to cover up her presence and the fact that she intercepted the photon message. But Eve's presence will be detected. By measuring the photons, Eve inevitably altered some of them.
Alice and Bob can further protect their transmission by discussing some of the exact correct results after they've discarded the incorrect measurements. This is called a parity check. If the chosen examples of Bob's measurements are all correct - meaning the pairs of Alice's transmitted photons and Bob's received photons all match up - then their message is secure.
Bob and Alice can then discard these discussed measurements and use the remaining secret measurements as their key. If discrepancies are found, they should occur in 50 percent of the parity checks. Since Eve will have altered about 25 percent of the photons through her measurements, Bob and Alice can reduce the likelihood that Eve has the remaining correct information down to a one-in-a-million chance by conducting 20 parity checks.
