Security

Public Key vs. Private Key Cryptography: What’s the Difference?

These two security tools can help organizations enforce strict user authentication.

Nathan Eddy works as an independent filmmaker and journalist based in Berlin, specializing in architecture, business technology and healthcare IT. He is a graduate of Northwestern University’s Medill School of Journalism.

Public key and private key cryptography are a central part of modern cybersecurity and identity and access management. They are also essential tools for organizations looking to secure communications and preserve data integrity.

What’s the difference? Public key cryptography (asymmetric encryption) involves a pair of keys, while private key cryptography (symmetric encryption) uses a single shared key.

Understanding the respective advantages of these systems and how they function is critical for organizations looking to bolster their cybersecurity defenses.

However, before investing in either, businesses must first evaluate their needs, considering scalability, speed and security parameters.

“The technical capabilities and ability to scale are two important elements to consider, but user adoption and ease of use are what make these systems work,” says Mike Kiser, director of strategy and standards at SailPoint. Here’s what you need to know:

Click the banner below to see how identity and access management can ensure seamless security.

Public Key vs. Private Key Encryption Explained

According to Sitaram Iyer, vice president of emerging technologies at CyberArk, public key cryptography involves a pair of keys that can be shared openly between users to encrypt messages. Private keys are kept secret to “ensure secure communication. Only the intended recipient can decrypt the message,” he says.

Private key cryptography also uses only a single key for both encryption and decryption, making it simpler but less secure in scenarios that require public sharing.

Kiser says symmetric encryption is a lot like a house key. “If you lose your key and your address is on it, you have a problem,” he says.

How Are Keys Generated?

The process of generating cryptographic keys is mathematically intricate, requiring a series of complex algorithms including Rivest-Shamir-Adleman (RSA), an asymmetric encryption algorithm, or Advanced Encryption Standard (AES), a symmetric encryption algorithm.

Public key infrastructure (PKI) systems often involve certificate authorities (CAs) that issue these keys.

“Organizations protect their PKI, often with hardware security modules, to ensure that keys remain secure,” Iyer says, highlighting the importance of secure key management.

He adds that dynamic key generation is essential for maintaining robust security.

Open-source platforms, such as Let’s Encrypt, have also simplified the process, enabling organizations to issue certificates without relying on costly, centralized authorities.

Organizations protect their PKI, often with hardware security modules, to ensure that keys remain secure.”

Sitaram Iyer Vice President of Emerging Technologies, CyberArk

What’s the Difference Between Public and Private Keys?

Public key encryption, or asymmetric encryption, enables secure communication between parties. “It’s a one-to-many model,” Kiser says, “in which a single private key can securely interact with an unlimited number of public keys.”

This scalability makes asymmetric encryption indispensable for modern internet protocols such as HTTPS and applications like email encryption or blockchain. Public keys also provide nonrepudiation — a unique advantage.

“Once a message is signed with a private key, it cannot be denied or altered,” Iyer says. This makes it indispensable for legal and compliance requirements. Ultimately, private key encryption is better for internal communications.

Learn how to integrate IAM with other technology in your environment.

Understand the difference between IAM, PAM and MFA.

Read about how businesses are improving user authentication beyond passwords.

What Are the Benefits of Key Encryption?

The benefits of encryption include confidentiality, integrity and authentication. For Kiser, both systems provide confidentiality and integrity by securing data against unauthorized access and tampering.

Authentication ensures that the message’s origin is verifiable. Public key encryption stands out in its ability to offer nonrepudiation.

“If a message is signed with a private key, it’s proof that the sender sent it,” Kiser said.

For businesses, the choice often depends on scalability and efficiency.

“Public key cryptography is more secure but slower due to its computational complexity,” Iyer says. “Private key encryption, while faster, requires robust key management due to the shared nature of the key.”

How Does This Encryption System Factor Into IAM?

Public key and private key cryptography play a critical role in identity and access management by securing user identities and ensuring that only authorized users gain access to systems. Public keys often verify digital signatures, while private keys protect sensitive communications.

“In IAM, it’s about more than just encryption,” Iyer said. “It’s about verifying who can access what.”

For example, OAuth, a popular authorization framework, uses tokens signed with private keys to manage user permissions. These tokens authenticate and authorize users, streamlining access control.

“The token is cryptographically signed to ensure it hasn’t been tampered with,” Kiser said.

As digital identities become more pervasive, cryptographic methods underpin emerging technologies such as mobile driver’s licenses and cryptographically verifiable digital IDs.

“The key is adoption and ease of use,” he said. “If encryption isn’t seamless, users won’t engage with it.”

matejmo/Getty Images