Since ancient times, people have relied on cryptography, the art of writing and solving encoded messages, to protect their secrets. In the fifth century, encrypted messages were inscribed on leather or paper and transmitted by human messengers. Today, cryptography helps protect our digital data as it travels over the Internet. Tomorrow, the field could take another leap forward; with the advent of quantum computers, cryptographers are harnessing the power of physics to produce the most secure passwords yet.
Historical Approaches to SecrecyThe word "cryptography" is derived from the Greek words "kryptos", meaning to hide, and "graphin " means to write. Cryptography allows two parties to communicate in plain sight, but in a language that the other party cannot read, rather than physically hiding the message from the enemy's eyes. To encrypt a message, the sender must use some systematic method (called an algorithm) to manipulate the contents. The original message, called plaintext, may be dislocated so that its letters are in an incomprehensible order, or each letter may be replaced by another. The resulting gibberish is called ciphertext, according to a crash course in computer science. In ancient Greek times
, the Spartan army encrypted messages using a device called a scytale, which, according to the Center for the History of Cryptography, consisted of a strip of leather around a wooden stick. When unraveled, the strip of paper appeared to have a string of random characters, but if wrapped around a stick of a certain size, the letters would arrange themselves into words. According to The Atlantic Monthly, this letter shuffling technique is known as a transposition cipher.
The Kama Sutra mentions an alternative algorithm called substitution, which suggests that women learn ways to keep their contact records hidden. To use substitution, the sender replaces each letter in the message with another; for example, "a" might become "Z," and so on. To decrypt such a message, the sender and receiver would need to agree on which letters to swap, just as a Spartan soldier would need to have the same size cipher.
The first cryptanalysthad to keep secret the specific knowledge (called a key) needed to reduce the ciphertext to plaintext to ensure that the message was secure. Breaking a cipher without a key requires a great deal of knowledge and skill.
The substitution cipher remained unbroken for the first millennium BC until *** Mathematician al-Kindi realized its weaknesses, according to Simon Singh, author of The Cipher Book (Random House, 2011). Noticing that certain letters were used more frequently than others, al-Kindi was able to reverse the substitutions by analyzing the letters that appeared most frequently in the ciphertext. *** Scholars became the world's foremost cryptanalysts, forcing cryptographers to adapt their methods.
As cryptographic methods advanced, cryptanalysts began to challenge them. One of the most famous skirmishes in this ongoing battle was the Allies' attempt to break the German Enigma Machine during World War II. The Mystery Machine encrypted messages using a substitution algorithm with a complex key that changed every day; and according to the CIA, cryptanalyst Alan Turing developed a device called a "bomb" to track the Mystery Machine's changing settings.
The sender of a classified message must come up with a systematic way of handling the context of the message that only the recipient can decipher. A confusing message is called a cipher. Cryptography in the Internet AgeIn the digital age, the goal of cryptography remains the same: to prevent information exchanged between two parties from being stolen by an adversary. Computer scientists often refer to the two parties as "Alice and Bob," a fictional entity that first appeared in a 1978 artwork describing a digital encryption method. Alice and Bob are often plagued by a nasty eavesdropper called "Eve".
A variety of apps use encryption to keep our data safe, including credit card numbers, medical records, and cryptocurrencies like Bitcoin. The technology behind Bitcoin, blockchain, connects hundreds of thousands of computers through a distributed network and uses encryption to protect each user's identity and maintain a permanent log of their transactions.
The emergence of the computer network raises a new question: if Alice and Bob are located in Universal, how can they ****enjoy a secret key without Eve snatching it? According to Khan Academy, public-key cryptography is one solution. The solution takes advantage of one-way functions, math that is easy to perform but difficult to reverse without key information. Alice and Bob exchanged ciphertexts and a public key under Eve's watchful eye, but each kept a private key for themselves. By applying both private keys to the ciphertext, the pair achieves a ****ty solution. Meanwhile, Eve is trying to decipher their sparse trail.
A widely used form of public key encryption, called RSA encryption, takes advantage of the tricky nature of prime factorization - finding two prime numbers that multiply gives you a specific solution. Multiplying two prime numbers takes no time at all, but even the fastest computers on the planet could take hundreds of years to reverse the process. Alice chose two numbers to create her encryption key, which made it very difficult for Eve to find those numbers. The Technology Behind Bitcoin
Blockchain connects hundreds of thousands of computers through a distributed network and uses encryption to protect each user's identity and records. To find an unbreakable code, today's cryptographers are looking to quantum physics. Quantum physics describes the strange behavior of matter on incredibly small scales. Like Schr?dinger's famous cat, subatomic particles exist in many states at once. But when the box is opened, the particle enters an observable state. In the 1970s and '80s, physicists began using this funky property to encrypt secret messages, a method now known as "quantum key distribution.Just as keys can be encoded in bytes, physicists now encode keys based on the properties of particles, usually photons. A malicious eavesdropper would have to measure the particles to steal the key, but any attempt to do so would change the behavior of the photons, alerting Alice and Bob to the security breach. This built-in alert system makes quantum key distribution "provably secure," Wired reports.
Quantum keys can be exchanged over long distances via optical fibers, but in the 1990s, another distribution route caught the interest of physicists. This technique, proposed by Artur Ekert, allows two photons to communicate over vast distances in space thanks to a phenomenon called "quantum entanglement.
"Entangled" quantum objects have the amazing property that if you separate them, they can sense each other even if they're hundreds of miles away," said Ekert, who is now a professor at the University of Oxford and director of the Center for Quantum Technologies at the National University of Singapore. Entangled particles behave as a single unit, allowing Alice and Bob to make a *** enjoyment key by making measurements at each end. If an eavesdropper tries to intercept the key, the particle reacts and the measurements change, according to Popular Science.
Quantum cryptography is more than just an abstract concept; in 2004, researchers transferred €3,000 into a bank account by entangling photons. In 2017, researchers fired two entangled photons from the satellite Mickey to Earth, keeping them connected for a record 747 miles (1,203 kilometers), according to New Scientist. Many companies are now embroiled in the race to develop quantum cryptography for commercial applications, and have had some success so far in order to secure the future of cybersecurity, "KDSPE" "KDSPs", they may also be in a race against time. "KDSPE" "KDSPs" "If there are quantum computers, existing cryptographic systems, including those that support cryptography, will no longer be secure," Ekert told Live Science. we don't know exactly when they'll be built - we'd better start doing something about it now.
Additional resources:
Use an analog enigma machine. Learn more about cybersecurity with a crash course. Discover the weirdness of "monster prime numbers" in this TED talk