Encryption

Encryption is a way to change information so only certain people can read it. It turns the original message, called plaintext, into a secret form called ciphertext. This helps keep messages safe.

To encrypt a message, a special secret number, called an encryption key, is used. This key is made by a set of rules called an algorithm. Only someone with the right key can change the ciphertext back to the original message.

People have used encryption for a long time, especially to keep important messages private. Today, encryption is used in computers and the internet. Modern encryption uses two main methods to keep our information safe.

History

Ancient

One of the earliest ways people hid messages was by replacing symbols, found in an ancient tomb in Egypt around 1900 BC. These symbols needed a special key to understand. This method was used in places like Ancient Greece and Rome, especially for secret military messages. A famous example is the Caesar cipher, where each letter in a message is moved a certain number of places in the alphabet to hide it.

Around 800 AD, a mathematician named al-Kindi found a way to guess these hidden messages by looking at how often each letter appeared. But later, new methods like the polyalphabetic cipher made it harder to guess by changing the hiding rule as the message was written.

19th–20th century

In the late 1700s, Thomas Jefferson thought of a way to hide messages using a wheel-like device called the Jefferson Disk. Though never built, the idea was to mix up letters in a message. A similar tool, the M-94, was made in 1917 and used by the US Army until 1942.

During World War II, the Axis powers used an even more complex machine called the Enigma Machine. Each day, it changed its mixing rule, making it very hard to break. However, the Allies used computers to find smarter ways to solve the puzzle.

Modern

Today, encryption helps keep messages safe when we use the Internet. As computers get faster, new ways to hide messages are created. One early method, DES, was broken in 1999 by a special computer built just for that purpose. Now, stronger methods like AES are used, making it almost impossible to guess the hidden message by trying every option.

Encryption in cryptography

Encryption helps keep information private and safe. When we send important things like passwords over the Internet, we want to make sure only the right person can read them. Encryption changes the information so that only someone with a special key can change it back to understand it.

There are two main ways to do this. In one way, called symmetric-key encryption, the same key is used to change the information and to change it back. Everyone who wants to talk securely needs to have this same key. In the other way, called public-key cryptography, anyone can use a public key to change the information, but only the person who receives it has a special private key to change it back to read it.

Pretty Good Privacy (PGP) is a free tool for encryption that was created in 1991 and is still used today.

Uses

Encryption helps keep messages secret. It has been used by militaries and governments for a long time. Today, it is used to protect information in many everyday things. For example, companies use encryption to keep data safe when it is sent or stored on devices like computers and USB flash drives. This protects personal information if a laptop or drive is lost or stolen.

Encryption is also important for protecting data when it is sent over networks, such as the Internet or mobile telephones. This stops unauthorized people from seeing the information as it travels. It is useful for e-commerce, wireless microphones, wireless intercom systems, Bluetooth devices, and bank automatic teller machines.

Regulatory compliance

Encryption helps follow rules that protect sensitive information. For example, under the HIPAA Security Rule, encryption is important for protecting electronic health information. There are also rules like the Payment Card Industry Data Security Standard that require encryption for credit card data when it is stored or sent over public networks.

Data erasure

Main article: Data erasure

Encryption can help delete data quickly. This is called crypto-shredding. For example, iOS devices use a special storage area to keep the key needed to unlock data. However, if someone gets physical access to the device, this method alone may not fully protect the information.

Limitations

Encryption helps keep digital data safe. As computers get faster, encryption gets stronger too. But even today’s encryption has some limits.

The length of the encryption key shows how strong the encryption is. For example, an old method called DES used a key that was only 56 bits long. This isn’t safe anymore because computers can try all the possibilities too quickly.

Quantum computing uses special science ideas to process data very fast—much faster than today’s computers. This speed could break current encryption methods. For example, a common encryption method called RSA uses big numbers that are hard to split apart without a special key. Quantum computers could split these numbers faster, making the data unsafe. Other methods like elliptic curve cryptography could also be at risk.

Right now, quantum computers are still new and not very powerful. They aren’t ready for everyday use and can’t handle big tasks yet. But scientists, including groups like the National Security Agency, are working on new encryption methods to stay safe in the future. These new methods could help protect data even from future quantum computers.

Attacks and countermeasures

Encryption helps keep information safe. It mainly protects data when it is stored or being sent. But the data can still be at risk when it is being used or processed, for example, by a cloud service.

Because of these limits, some people try to find ways around encryption. They might try to steal the encrypted data or attack the keys used to unlock it. Some technologies try to make these attacks harder by changing or moving the encrypted data.

The debate around encryption

Encryption helps keep our digital messages safe, but it can also be a topic of discussion. The big talk about encryption started in the 1990s when the US government tried to limit its use, saying it might be risky for safety. People have different ideas: some worry that encryption can help criminals hide, while others think it protects our private messages. This discussion grew when big companies like Apple and Google began using encryption by default on their devices, causing many debates among governments, companies, and users.

Encryption can keep messages secret, but we also need other ways to make sure messages are not changed or faked. This can be done using special checks or signs. Some tools can do both encryption and these checks together. Even with good tools, using them the right way can be hard. Small mistakes can sometimes let others break the security. Attackers can also find ways to get information without breaking the encryption, like by watching how messages are sent.