What Is a Public Key?

A public key is a type of cryptographic code to encrypt and decrypt sensitive information. In cryptography, “keys” are information that scrambles data, making it uninterpretable without an algorithm designed to unlock it. A public key and its counterpart, a private key, form the cornerstone of public key cryptography. 

Why are public keys important?

Public keys are important because they help protect sensitive information and send it securely. 

For example, imagine sending a confidential letter only intended for the recipient. You might consider sending the letter in a locked box, but you would also have to send the key. However, if someone intercepts your package, they’ll have access to the key, can easily unlock the box, and can read your letter. This scenario is the challenge that public key encryption aims to solve.

With public key encryption, instead of one key, you have two. So when sending your letter in a locked box, your public key would protect (or encrypt) the box, and only the recipient's private key can unlock (or decrypt) it. This way, even if someone intercepts your package, they can't open the box without the recipient's private key. The public key ensures your message remains secure during its journey.

What is public key encryption?

Public key encryption, also known as asymmetrical encryption and public key cryptography, is a type of encryption that secures data transfer over the internet. The term “public” means it's openly distributed and accessible to everyone, whilst the “private” key is known only to the owner. 

What are some uses of public keys?

Public keys are helpful in secure digital information transfers, such as with cryptocurrencies and digital signatures. For a cryptocurrency wallet, the public key is an address people can use to send cryptocurrency. It's similar to an email address but for cryptocurrency. On the other hand, your private key allows you to access and manage your crypto. With it, you can prove the cryptocurrency belongs to you.

You can also use public keys to create digital signatures. Just as you sign a paper document to verify it came from you, a digital signature does the same for electronic records. Here, the private key creates the signature, and the public key validates it. It guarantees that no one tampered with the message during transit and authenticates the sender's identity.

Related terms

• Hashing

• Encapsulation

• Private key

• Authentication

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A public key is a type of cryptographic code you use to encrypt and decrypt sensitive information. It’s a vital strategy for securing data transfer via the internet. Continue learning about public key encryption and other cybersecurity issues with the Google Cybersecurity Professional Certificate on Coursera. Learn how to use essential job tools like Splunk, Chronicle, playbook, and more while gaining the skills you need to become job-ready.