If you’ve ever used Bitcoin or any cryptocurrency, come across a digital certificate, or simply noticed the padlock icon in a website’s address bar (https://), you’ve already interacted with a public key. While it may sound complicated, understanding what it is and how it works is easier than it seems—and it’s essential if you want to browse or transact safely online.

What a Public Key Is in Simple Terms

A public key is a mathematically generated string of characters used to encrypt information or verify digital signatures. It’s part of a system called asymmetric cryptography, which relies on two keys:

  • Private key: must be kept secret.
  • Public key: can be shared freely.

The main advantage of this system is that what one key encrypts, only the other can decrypt. For example, if someone wants to send you information securely, they use your public key to encrypt it. Only you can open it with your private key.

In the context of cryptocurrencies, public keys are generated automatically by wallets and enable you to receive funds securely. This system makes transactions both verifiable and private at the same time.

What a Public Key Is Used For

Public keys are used in many different scenarios:

  • Cryptocurrency transactions: they function as addresses to receive funds.
  • Secure email: such as PGP-based systems.
  • Secure web browsing (HTTPS): websites use public keys to establish encrypted connections.
  • Digital signatures: to verify that a document hasn’t been altered.
  • Digital certificates: which confirm the authenticity of a website or software.

Sharing a public key is not a security risk, because its purpose is precisely to allow others to encrypt information intended for you. The associated private key is what must be protected.

How a Public Key Is Generated

A public key is created alongside its private key using complex cryptographic algorithms. Some of the most common include:

  • RSA
  • ECDSA (elliptic curves)
  • EdDSA

In practice, cryptocurrency wallets, web browsers, and security applications generate these keys automatically. When a user creates a new wallet, a key pair is generated:

  • A private key that is stored securely.
  • A public key that can be shared to receive assets or verify signatures.

This happens in seconds and requires no technical knowledge, since the software handles all of the math behind the scenes.

Example: Key Generation in a Wallet

When you create a new crypto wallet—such as a Bitcoin or Ethereum wallet—the system automatically generates a key pair. For example:

Private key:
L1aW4aubDFB7yfras2S1mMEbRoXU3kVdMRpCwzFz8z3mxGXXJF6y
This key must remain 100% secret. It’s the only way to access and move the associated funds.

Public key (receiving address):
1FfmbHfnpaZjKFvyi1okTjJJusN455paPH
This is the address you can share with others to receive cryptocurrency. By itself, it does not pose a security risk.

In modern wallets, this public key is often shown as a QR code, making it easy to scan and receive funds quickly and securely.

How It Relates to Public Key Infrastructure (PKI)

In more advanced contexts—such as websites, enterprise applications, and digital certificates—public keys are part of a broader system called PKI (Public Key Infrastructure).

This system:

  • Issues digital certificates that link keys to verified identities.
  • Verifies the authenticity of websites.
  • Manages key expiration and revocation.

Thanks to PKI, you can trust that communication with a website is legitimate and that transmitted data is protected against interception.

Why It’s Important to Understand Public Keys

Even though you don’t need technical expertise to use public keys, understanding the basics helps you make better digital security decisions. Public keys are essential for ensuring confidentiality, authenticity, and integrity of information in the digital world.

Learning how they work helps you:

  • Make safer blockchain transactions.
  • Understand how SSL certificates work.
  • Appreciate the importance of protecting the associated private keys.

Public Keys: The Invisible Foundation of Your Digital Security

Understanding what a public key is and how it’s generated isn’t just technical trivia—it’s understanding how security works in the digital age. From receiving cryptocurrency in your wallet to browsing the internet safely, this technology is present in every click you make.

More and more people use cryptography without realizing it. Learning the fundamentals is the first step toward greater digital autonomy and better protection of your personal data.