What Is Encryption

Encryption is a technology that transforms data using a specific algorithm so that only those with the correct key can read the original data. Think of it like placing a letter in a locked box before sending it - anyone without the key cannot see the contents.

Symmetric-Key and Public-Key Encryption

Uses the same key for encryption and decryption. AES is the most common example. Fast but key sharing is a challenge.

Uses different keys for encryption and decryption. RSA is the most common example. Solves the key sharing problem but is slower. See public-key cryptography for details.

In practice, TLS communication uses a hybrid approach: public-key encryption securely exchanges a shared key, and subsequent data transfer uses the faster symmetric-key encryption.

Everyday Uses of Encryption

HTTPS: Encrypts communication with websites. The padlock icon in the address bar indicates this.
Messaging Apps: End-to-end encryption in apps like Signal means even the service provider cannot read your messages.
Disk Encryption: iPhone encryption and Windows BitLocker protect your data even if the device is lost or stolen.
VPN: Encrypts all internet traffic, enabling safe communication even on public Wi-Fi.

What Encryption Cannot Protect

Encryption is not a silver bullet. While it prevents eavesdropping on communication channels, it cannot help when users voluntarily enter passwords on phishing sites or when malware directly reads data on a compromised device.

To learn more about this topic, see our article What Is Encryption? How It Works and Its Types.

Common Misconceptions

If it is encrypted, it is absolutely safe: Encryption prevents eavesdropping on communication channels, but it cannot protect against phishing or malware that compromises the device itself.
Encryption is only for experts: Everyone benefits from encryption daily through HTTPS web browsing, messaging apps, and smartphone disk encryption.

Symmetric-Key vs Public-Key Encryption

Symmetric-Key Encryption

Same key for encryption and decryption. Fast but key sharing is a challenge. AES is the most common.

Public-Key Encryption

Different keys for encryption and decryption. Solves key sharing but slower. RSA is the most common.

Encryption