What is Encryption?

Encryption is the process of transforming readable text or data, called plaintext, into unreadable code called ciphertext. After the data is transformed, it is said to be encrypted. The reverse transformation process from ciphertext to plaintext is called decryption.

Background: There are many methods of encryption. Each method aims to prevent decryption by anyone who doesn’t have a specific secret key, such as a password, fingerprint, or physical device.

The big picture: Different forms of encryption have been used for thousands of years to secure communications. Modern mathematics and technology allow for widespread use of encryption methods that make it computationally impossible for third parties to decrypt the encrypted data without the secret key.


  • Modern encryption allows people to put their data into digital safes that have locks that are physically impossible to pick.
  • Encrypting data is like translating it into a language that only the person with the secret key can understand. This prevents unauthorized people from reading your letters even if they take it out of the envelope.

Why it matters: Encryption can be used to protect documents and information where physical security isn’t enough or doesn’t help.

  • People can use encryption to prevent third parties from eavesdropping on or tampering with their communications.
  • Businesses can use encryption to deliver digital goods to their customers and safeguard important information about their clients, employees, or practices.
  • Governments can use encryption to protect secrets about their intelligence and military operations, issues concerning national security, and data about their citizens.

Encryption is for everyone: Individuals use encryption for many of their daily activities.

  • Smartphones, personal computers, and external hard drives are often encrypted by default or by user configuration. Encrypting devices helps prevent thieves from retrieving data from stolen devices.
  • Encryption helps protect debit and credit card information when they are used in-store and online.
  • Devices that use Bluetooth, such as smart watches or garage door openers, use encryption to prevent unauthorized use.
  • People can use encryption to verify the identities of the websites they browse, the software they download, and the documents they receive.
  • Individuals can use encryption to write private notes and send private messages, emails, and calls to their friends and family.

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