What is GPG?

GPG (GNU Privacy Guard) is a free program that lets you encrypt (hide) messages and files so only the intended person can read them, and also lets you sign them to prove they really came from you. It uses a system of public and private keys to do this.

Let's break it down

  • Free program: You don’t have to pay to use it; anyone can download it.
  • Encrypt (hide) messages and files: Turn readable text into scrambled code that looks like nonsense to anyone without the right key.
  • Only the intended person can read them: The person you choose has a special “private” key that can unlock the scrambled message.
  • Sign them: Add a digital fingerprint that shows the message really came from you and wasn’t changed.
  • Public and private keys: Two related passwords - one you share openly (public) and one you keep secret (private). The public key locks the message; the private key unlocks it.

Why does it matter?

Because it protects your private information from eavesdroppers, hackers, and even governments, ensuring that only the people you trust can see what you send. It also gives you a way to prove the authenticity of your communications, which is crucial for trust online.

Where is it used?

  • Secure email: People encrypt their emails so only the recipient can read them.
  • Software distribution: Developers sign program files so users can verify they haven’t been tampered with.
  • Cloud storage: Files are encrypted before uploading, so the cloud provider can’t read them.
  • Instant messaging plugins: Some chat apps use GPG to encrypt messages end-to-end.

Good things about it

  • Completely free and open-source, so anyone can inspect the code.
  • Strong encryption that is widely trusted by security experts.
  • Works on many operating systems (Linux, Windows, macOS).
  • Allows both encryption and digital signatures in one tool.
  • No need for a central authority; you can create your own keys.

Not-so-good things

  • Can be confusing for beginners; managing keys and passphrases takes learning.
  • Requires both parties to exchange and verify public keys correctly, which can be a hassle.
  • Large encrypted files can be slower to create and open compared to plain files.
  • If you lose your private key or forget its passphrase, your encrypted data is effectively lost.