Universal 2nd Factor (U2F): History, Evolution, Advantages

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Access Control, Secure Access, IT Management

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TL;DR

Universal 2nd Factor (U2F) is an open authentication standard that strengthens security by requiring users to verify their identity with both a password and a physical cryptographic key. Developed in 2014 through a partnership between Google, Yubico, and NXP Semiconductors under the Fast Identity Online (FIDO) Alliance, U2F works by sending an encrypted challenge to a hardware key plugged into a Universal Serial Bus (USB) port. Keys cannot be cloned, require no drivers, and offer strong phishing resistance — making U2F a practical upgrade over passwords alone for both consumers and enterprise environments.

Why isn't a password alone enough to protect your accounts?

How can you protect your company when passwords just aren't enough? What secondary challenge can you offer that's almost (but not quite) immune to hacking?

Enter U2F.

The U2F protocol allows you to send a cryptographic challenge to a device (typically a key fob) owned by the user. A password starts the process, but the digital key is required to gain access.

The FIDO U2F protocol was developed in 2014, and since then, the standards have been honed, refined, and updated. More users are growing accustomed to the idea of cryptographic keys. Some even demand this protection to keep their data safe and secure.

How did U2F come to be?

Most consumers know at least something about two-factor authentication. As bloggers explain, each time you must use a bank card and a Personal Identification Number (PIN), you've used two sets of data to get into something you need. Universal 2nd Factor works in a similar manner, and it's something advocates have long pushed for.

In 2012, rumors of a Google project that used key fobs to replace standard keyword entries began appearing on industry blogs. Experts weren't sure how the tools would work, but excitement was building. Blogs with titles such as "The Plot to Kill the Password" kept interest alive.

In 2014, the standards were proposed in a partnership between:

Google
Yubico
NXP Semiconductors

The open-source standards eventually came under the heading of the FIDO (Fast Identity Online) Alliance, which continues maintenance and administration today.

How does U2F work?

Think of Universal 2nd Factor as a new security gateway people must pass through to get to protected resources. While those users still need passwords to kick off the process, they must also have a physical device with them to complete your authorization steps.

In simple terms, a U2F process looks like this:

Password: The user heads to a website and enters a username and password recognized by that site.
Challenge: With the appropriate username and password recognized, the system sends a challenge to a key that the user has plugged into a Universal Serial Bus (USB) port. The communication is encrypted during transport.
Response: The key lights up or otherwise acknowledges that the challenge has been received. The user presses a button to finalize the connection.

What are the key security properties of a U2F device?

Asymmetric cryptography (FIDO-specified)
Sensitive data remains on the device at all times
Communicates via Human Interface Device (HID) protocol over USB
No driver or software download required

What happens when a key is lost or unavailable?

Users are cautioned to keep a spare security key available at all times. If it's lost, it's very difficult for users to gain access to protected resources. Security is crucial in the U2F environment, rather than user convenience, so people simply must be careful with the keys once they're authorized.

Cannot be cloned, as the private information on the key can't be extracted
Not Bluetooth-enabled, so no wireless attack vectors
No batteries required
No ongoing maintenance needed

To end users, keys represent strong security with little hassle. For some people, it's a perfect combination.

How can organizations implement U2F?

The Universal 2nd Factor protocol is open, so any developer can use it. But a vendor's role is crucial.

How do vendors and developers support U2F?

Consumers typically buy keys from third parties, including YubiKey, Titan, and others, and companies must ensure that the keys purchased truly can communicate with their systems. Some companies instruct consumers to buy keys only from partners they've vetted and trusted. If you're in a sensitive market, such as banking, this might be a good option.

What does the setup process look like for users?

Customers claim that setting up a U2F key is intimidating, and it involves several steps, such as:

Signing in. Users start the process by heading to a website of choice and adding their usernames and passwords.
Token registration. Users highlight the fact that they've bought a key.
Plugging in and registering. Users put the key into the computer, and they might be asked to use Short Message Service (SMS) verifications to get started.
Repeating. The registration must be done for every website you want to authenticate using the U2F token.

The coding requirements for website developers are minimal. Teams must develop registration processes, so users can add this mode of authentication to their logins. Developers often report that this takes very little time and technical expertise.

Get started with U2F

We've partnered with Yubico to bring U2F to all of our clients. We know simple passwords aren't enough, and we want to be part of the solution.

Click to discover how Okta's universal 2nd factor solutions can better protect your users.

Frequently asked questions

What is U2F (Universal 2nd Factor) and how is it different from standard two-factor authentication?

U2F (Universal 2nd Factor) is an open authentication standard that uses a physical cryptographic key to verify identity. Unlike standard 2FA, which may rely on Short Message Service (SMS) codes or app-generated tokens, U2F uses asymmetric cryptography and keeps sensitive data stored directly on the hardware device, making it significantly harder to phish or intercept.

Who developed the U2F (Universal 2nd Factor) standard?

The U2F (Universal 2nd Factor)standard was developed in 2014 through a collaboration between Google, Yubico, and NXP Semiconductors. It was subsequently adopted and is now maintained by the FIDO (Fast Identity Online) Alliance.

What happens if a user loses their U2F (Universal 2nd Factor) security key?

Losing a U2F (Universal 2nd Factor) key makes it very difficult to regain access to protected resources, since security is prioritized over user convenience in the U2F model. Users are strongly advised to keep a spare security key registered and available at all times.

Do U2F (Universal 2nd Factor) keys require special software or drivers to work?

No. U2F (Universal 2nd Factor) keys communicate with the host computer via the Human Interface Device (HID) protocol over a Universal Serial Bus (USB) connection, which means no additional drivers or software downloads are required.

Can a U2F (Universal 2nd Factor) key be cloned or compromised remotely?

No. The private information stored on a U2F (Universal 2nd Factor) key cannot be extracted, which means the key cannot be cloned. Most keys are also not Bluetooth-enabled, eliminating wireless attack vectors and removing the need for batteries or ongoing maintenance.

How much technical effort is required for developers to add U2F (Universal 2nd Factor) support?

The coding requirements are minimal. Developers primarily need to build a registration flow so users can enroll their keys. Developer accounts suggest that implementation typically requires very little time or specialized technical expertise.