FIDO Security Key vs OTP Hardware Token

FIDO Security Key vs OTP Hardware Token: Which Is Better for Multi-Factor Authentication?

Multi-factor authentication (MFA) has become a critical security requirement for protecting digital identities. By requiring users to present multiple authentication factors, MFA significantly reduces the risk of account compromise caused by stolen passwords, phishing attacks, or credential reuse.

Two of the most widely deployed hardware authentication technologies today are:

• FIDO security keys
• OTP (One-Time Password) hardware tokens

Both technologies strengthen authentication security, but they operate differently and are suited for different environments.

This article explains the differences between FIDO security keys and OTP hardware tokens , their advantages and limitations, and why many organisations deploy both technologies together as part of a modern MFA strategy.

What Is a FIDO Security Key?

A FIDO security key is a hardware authentication device that supports the FIDO2 or U2F authentication standards.

FIDO authentication uses public-key cryptography. During login, the security key signs a cryptographic challenge issued by the service using a private key stored securely inside the device.

Typical authentication flow:

1. The user enters their username.
2. The application sends a challenge to the FIDO security key.
3. The user touches the key or verifies biometric authentication.
4. The key signs the challenge and authentication is completed.

Because the private key never leaves the device, FIDO authentication provides very strong protection against phishing and credential theft .

FIDO security keys are commonly used for:

• passwordless authentication
• phishing-resistant login
• workforce identity protection
• secure access to cloud applications

Deepnet Security provides SafeKey FIDO security keys, designed for enterprise deployments and compatible with modern identity platforms such as Microsoft Entra ID, Okta, and Google Workspace .

What Is an OTP Hardware Token?

An OTP hardware token is a device that generates a one-time password used during login.

The most widely used OTP standard is OATH TOTP (Time-Based One-Time Password) .

During authentication:

1. The user enters their username and password.
2. The system requests an OTP code.
3. The user reads the code from their hardware token.
4. The code is entered to complete authentication.

OTP tokens have been widely deployed for many years in industries such as banking, government, healthcare, and enterprise IT.

Deepnet Security is one of the leading suppliers of OATH-compliant OTP hardware tokens , including the SafeID token family, which is widely used for enterprise MFA deployments.

OTP tokens remain popular because they are:

• easy to deploy
• compatible with many systems
• simple for users to understand
• highly reliable hardware devices

Key Differences Between FIDO Keys and OTP Tokens

Although both technologies improve authentication security, they operate in different ways.

Feature	FIDO Security Key	OTP Hardware Token
Authentication method	Public-key cryptography	One-time numeric code
Phishing resistance	Very high	Good but not absolute
Passwordless login	Yes	No
User interaction	Touch key or biometric	Enter numeric code
Legacy system compatibility	Limited	Very broad
Deployment complexity	Moderate	Simple

The most important differences relate to phishing resistance, compatibility, and user experience .

Phishing Resistance

Phishing attacks remain one of the most common causes of account compromise.

FIDO Security Keys

FIDO authentication is specifically designed to prevent phishing attacks.

Because authentication is tied to the legitimate website's domain, a FIDO key cannot be tricked into authenticating a fake website.

This makes FIDO authentication one of the most effective defences against credential phishing.

OTP Tokens

OTP authentication significantly improves security compared to passwords alone, but attackers may still attempt to capture OTP codes through phishing or real-time relay attacks.

For this reason, FIDO authentication is generally considered more resistant to phishing attacks than OTP authentication .

Compatibility with Enterprise Systems

OTP tokens remain widely used because of their broad compatibility .

OTP Tokens

OTP authentication works with many systems including:

• VPN authentication
• RADIUS authentication
• legacy enterprise applications
• cloud authentication systems
• Microsoft Entra ID MFA

Because OTP tokens follow the OATH TOTP standard, they can integrate easily with many authentication platforms.

Deepnet SafeID OTP tokens are widely deployed for securing VPN access, enterprise applications, and Microsoft Entra ID environments.

FIDO Security Keys

FIDO authentication requires support for FIDO2 or WebAuthn.

Most modern identity platforms support FIDO authentication, including:

• Microsoft Entra ID
• Google Workspace
• Okta
• WebAuthn-enabled applications

However, some older enterprise systems may not yet support FIDO authentication.

Passwordless Authentication

One of the biggest advantages of FIDO authentication is the ability to support passwordless login.

FIDO Security Keys

FIDO2 security keys allow users to authenticate without entering a password.

Users simply:

• insert the security key
• touch the key or verify biometrics

This improves both security and usability.

Deepnet SafeKey FIDO security keys support passwordless authentication across modern identity platforms.

OTP Tokens

OTP tokens are typically used as a second authentication factor alongside a password.

They cannot replace passwords entirely.

However, OTP tokens remain an effective and widely supported MFA method.

User Experience

Both authentication methods are relatively simple for users.

FIDO Security Keys

Users authenticate by touching the security key or verifying biometrics.

This eliminates the need to type codes and can speed up login.

OTP Tokens

Users read a code displayed on the token and enter it during login.

Although this requires slightly more interaction, the process is familiar to many users.

Why Many Organisations Use Both

In real-world enterprise environments, organisations often deploy both FIDO security keys and OTP tokens .

Each technology addresses different requirements.

Use Case	Recommended Method
Passwordless authentication	FIDO security key
Phishing-resistant login	FIDO security key
Legacy system authentication	OTP token
VPN authentication	OTP token
Backup authentication method	OTP token

Supporting both technologies allows organisations to achieve maximum flexibility and compatibility .

Hardware Authentication with Deepnet Security

Deepnet Security provides a comprehensive hardware authentication ecosystem combining FIDO keys, OTP tokens, MFA software, and cloud-based token lifecycle management .

SafeKey FIDO Security Keys

Deepnet SafeKey devices support:

• FIDO2 / WebAuthn authentication
• U2F authentication
• NFC authentication
• fingerprint authentication models

SafeKey devices enable organisations to deploy passwordless authentication and phishing-resistant login .

SafeID OTP Hardware Tokens

Deepnet SafeID OTP tokens are widely used in enterprise MFA deployments.

They support the OATH TOTP standard and are commonly used for:

• Microsoft Entra ID MFA
• VPN authentication
• RADIUS authentication
• enterprise application security
• legacy system protection

Deepnet is recognised as one of the leading suppliers of OTP hardware tokens for enterprise environments .

DualShield Unified MFA Platform

Deepnet's DualShield Unified MFA Platform integrates multiple authentication methods into a single solution.

DualShield supports:

• FIDO security keys
• OTP hardware tokens
• mobile authenticator apps
• push authentication
• SMS authentication
• biometric authentication

This allows organisations to implement flexible MFA policies tailored to different users and applications .

SafeID Token Service

Deepnet also provides SafeID Token Service (STS), a cloud service for token enrolment and lifecycle management.

STS enables organisations to:

• enrol FIDO keys and OTP tokens
• assign tokens to users
• manage token inventory
• replace lost or damaged devices
• manage authentication devices across large user populations

A key advantage of SafeID Token Service is that it provides unified management for both SafeKey FIDO devices and SafeID OTP tokens .

Choosing the Right MFA Strategy

There is no single authentication method that fits every environment.

FIDO security keys offer the strongest protection against phishing and enable passwordless authentication.

OTP tokens provide excellent compatibility with existing systems and remain widely used in enterprise MFA deployments.

For many organisations, the best strategy is to deploy both technologies together within a unified MFA platform .

Strengthen Authentication Security with Deepnet

Deepnet Security provides a complete authentication ecosystem including:

• SafeKey FIDO security keys
• SafeID OTP hardware tokens
• DualShield Unified MFA Platform
• SafeID Token Service for cloud-based token enrolment and lifecycle management

Together these solutions enable organisations to deploy secure, scalable, and flexible multi-factor authentication infrastructures .