How end-to-end encryption protects messages, even from service providers

Watch how the Enigma machine encrypts messages and learn about its critical design flaw

Using settings selected from a series of rotors and a plugboard that let operators swap letters with any of their choosing, the machine lit up the output letter for each letter typed. While this system could generate messages requiring any of 150 quintillion potential keys, the machine's reflector never encrypted a letter as itself, providing an entry point for exploiting the system.

A mathematical breakdown of how RSA encryption uses prime numbers to encrypt data

This form of asymmetric cryptography uses mathematical functions that rely on the product of two large prime numbers. Because traditional computers struggle to factor such products, obtaining the private keys needed to decrypt messages becomes effectively impossible. This security can be reinforced with larger prime numbers, though this makes encryption more computationally taxing.

Practice encrypting and decrypting text using an online library of ciphers

This tool provides users with customizable protocols, including Caesar, Affine, and Vigenère ciphers, to hide messages in transformed text and convert them back into legible formats. Mechanisms are also available to convert text into other communication languages, such as Morse code and URL encoding.

WeChat: The world's second-largest messaging platform

The central technology in Tencent's empire, WeChat boasts roughly 1.4 billion users and provides a platform for the company to expand its ambitions in digital payments, e-commerce, and more. Unlike rival WhatsApp (owned by Meta), WeChat was built as a "superapp"—a single place where users are provided a wide range of features.

The dark web protects free speech from censorship and authoritarian oversight

Encrypted networks allow users with internet access anywhere in the world to view blocked content and avoid surveillance when communicating evidence of abuse to independent journalists. The same networks can support democracies by helping activists coordinate protests on dark web forums.

The mathematics of quantum-based cryptography, and why existing data is already at risk

Seeing the potential of this technology, some governments and malicious actors are thought to have already started storing encrypted data, in the hopes that quantum computers within the next 10 to 20 years will be able to decrypt it. As of 2022, the National Institute of Standards and Technology had selected four algorithms for inclusion in a quantum-resistant encryption standard.

A visual guide to how bitcoin transactions work and rely on cryptography

The "crypto-" in cryptocurrencies like bitcoin refers to the mathematical functions that generate pairs of public and private keys and encrypt data in blocks. When combined, these systems secure transactions on the network, verify digital asset and token transfers, and contribute to end-user anonymity.

Onion routing disguises internet traffic in layers resembling a nesting doll

Data is encrypted at least three times before being sent to a node—a server that can only decrypt one layer. Then, the underlying encrypted data is relayed to another node, and the process repeats until all layers are decrypted. Thousands of possible nodes make it extremely difficult to trace activity within the system.

Understanding the Diffie-Hellman key exchange, an example of public key cryptography

Published in 1976 by Whitfield Diffie and Martin Hellman, the system involves two parties combining each of their unique private keys with a public key using a mathematical function. The combinations are exchanged and mixed to establish a common key that no third party can determine. The Diffie-Hellman system underlies many encryption protocols for internet traffic.

Passkeys, a new authentication method, aim to replace traditional passwords

Passkeys use cryptography keys to secure logins without passwords, resisting phishing and risks from data breaches. The FIDO Alliance developed passkeys as a combination of public and private keys for authentication.

Decentralized applications are blockchain-based and run without a central authority

These apps use smart contracts to automatically execute functions, ensuring security, transparency, and censorship resistance. Built on platforms like Ethereum, Solana, and Binance Smart Chain, DApps power DeFi, NFTs, gaming, and social media, offering users control over their data and assets.

Smart cities without strong cybersecurity can leave utilities extremely vulnerable

Insecure devices connected to the Internet of Things pose risks to the entire network, which cybercriminals can hijack to compromise infrastructure and private resident data. Poorly secured systems that become inoperable can undermine the promise of smart cities by worsening the quality of life.

During flights, cell phones can act like signal jammers as they search for service

When farther from cell towers, these devices expend more energy to emit more powerful signals, which can overwhelm any ground-based tower or radio telescope they fly past. Rather than protecting the flight, airplane mode conserves a cell phone's battery.

Privacy advocates warn menstrual cycle apps could put women at legal risk in certain states

Smartphone apps that women may use to track their menstrual cycle and identify times of peak ovulation are not covered by data privacy laws. Included data could potentially be used against women during prosecution in states with abortion restrictions.

How the people behind spam text messages make money

If you've ever gotten a text message from a scammer—sometimes even just someone from an unknown number saying hello and calling you by the wrong name—you've probably wondered what they're trying to get out of you. This podcast answers that question. Hint: The answer has to do with cryptocurrency.

A brief guide to espionage

Spies have one of the most challenging and dangerous jobs in the world, risking their lives and legacy to extract secrets in the interest of their country. This in-depth explainer breaks down one of the profession's oft-ignored aspects: The...

Contactless credit cards descend from a batteryless Cold War listening device

The same physics that let Soviet spies eavesdrop on the US ambassador in 1945 underlie contactless payment methods today. The device is a passive chip powered wirelessly by incoming radio waves.

EOS and maximum length tokens tell an LLM when to stop generating a response

Tokens are words or subwords (e.g., prefixes) that a large language model processes to generate a response. During training, the model is taught that if it ever generates a special token called end-of-sequence, its response is complete.

Entanglement creates correlations between particles across vast distances

Quantum entanglement occurs when two or more particles become linked, resulting in correlated properties. Scientists have ruled out hidden variables and have shown that these correlations depend on how and when measurements are made—not on faster-than-light communication.

Ethereum’s biggest risks and top criticisms

As it evolves, critics say Ethereum’s constant changes make the platform overly complex and fundamentally less secure. They also say the Ethereum Foundation and a handful of developers wield too much control over the crypto platform, and that gas fees are prohibitively expensive. Some criticisms are addressed in Ethereum’s roadmap, but others strike at the crypto platform’s core. Go deeper on why here.

In 2025, Apple devices couldn't send audio messages with the phrase 'Dave & Buster's'

The transcription engine in iOS 18, which converts speech to text in the Messages app, had been incorrectly processing phrases with the ampersand ("&") symbol. The error was corrected via a bug fix after extensive user error reports.

Trademarks protect the branding of a service or product, while patents protect the product or service itself

Trademark protections cover the branding of a service or product, like its logo, its smell, or even its shape. However, patent protections give inventors exclusive control over a new product—as long as those inventors disclose how the product works and how they made it.

Wolbachia is a naturally occurring bacterium being employed to fight dengue

Scientists are fighting dengue spread in a roundabout way: injecting bacteria into Aedes aegypti mosquito eggs, which blocks the dengue virus from replicating in the tissue of mosquitoes. Researchers hope the bacterium will be passed to future generations, inoculating them against dengue. Wolbachia is also being investigated to combat other mosquito-borne diseases.

The selfie camera exists thanks to Einstein's discovery of the photoelectric effect

Smartphone cameras utilize sensors such as CMOS or CCD to capture light by converting it into electrical signals through the photoelectric effect. Einstein explained this effect by demonstrating that light behaves as both particles and waves simultaneously, a discovery that earned him the Nobel Prize in physics.

Taylor Swift helps drive fan engagement by filling her music with easter eggs

Taylor Swift is famous for incorporating Easter eggs—specifically, hidden messages and clues—in her music. Her music videos are often sprinkled with visual nods to her past, and fans pore over her lyrics for the cryptic messages they frequently contain.

See the evolution of Ebola vaccine and treatment development.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

The story of Dollree Mapp, whose legal challenge over her 1957 conviction for possessing "obscene material" led to a major strengthening of the Fourth Amendment

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

Prince's sexually explicit 1984 track 'Darling Nikki' attracted the ire of the Parents Music Resource Center, an advocacy group that inspired the Parental Advisory sticker, even though the song ends with a Christian message.

A Yale student wrote a profound essay about the consulting industry's influence on elite college students that was published in a book of her writing after she died in a post-graduation car accident.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.