Common Mode of Two Step Authentication: Methods, Security Levels, and Best Practices

This guide is for anyone seeking to understand the most common modes of two-step authentication, their security levels, and best practices. As online threats increase, understanding two-step authentication is essential for protecting your accounts. The most common modes of two-step authentication include SMS/Email One-Time Passcodes, Authenticator Apps, Push Notifications, Biometrics, and Hardware Security Keys. These methods are widely used to secure everything from email accounts to financial information, providing an extra layer of protection beyond a username and password.

Two-step authentication works on a simple but powerful principle: even if an attacker knows your password, they still cannot gain access without a second factor. This approach ensures that only the user can complete the authentication process and be granted access to an account or system.

Two-factor authentication (2FA) is a security process that requires users to verify their identity in two unique ways before gaining access to a system. For example, when withdrawing cash from an ATM, you must insert your bank card (something you have) and enter your PIN (something you know), or when logging into an account, you might enter your password and then a code sent to your phone. Using two-factor authentication is like using two locks on your door, making it much more secure than using just one.

Authentication is the process of verifying the identity of a user, device, or system to ensure that only authorized individuals can gain access to sensitive information or resources. In an era where digital threats are constantly evolving, robust authentication is essential for maintaining the security of online services and protecting valuable data.

The authentication process typically involves confirming that the person or device attempting to access an account is truly who they claim to be. This is achieved by requiring one or more authentication factors — such as something the user knows (like a password), something they have (like a mobile device or hardware token), or something they are (such as biometric data). By verifying these factors, organizations can significantly reduce the risk of unauthorized access and safeguard sensitive information from cybercriminals.

Multi-factor authentication (MFA) takes this a step further by requiring users to provide two or more independent authentication factors before being granted access. This extra layer of security makes it much more difficult for attackers to compromise accounts, even if one factor — such as a password — has been exposed. As a result, MFA has become a critical component of modern security strategies, helping to verify user identity and protect against a wide range of cyber threats.

In 2026, two-step authentication implementations are categorized by the type of "factor" they utilize: something you know, something you have, or something you are. These three categories are:

In addition to these three categories, other factors — such as location-based authentication or behavioral biometrics — can be used to further enhance security in multi-factor authentication systems.

Using multiple authentication factors ensures that even if one factor is compromised, attackers cannot complete the authentication process.

Two-factor authentication (2FA) is increasingly important as more personal and business activities move online, making accounts vulnerable to hacking. Two-step authentication is increasingly used to protect online transactions and sensitive information.

Many organizations are required to implement two-step authentication for sensitive transactions to achieve regulatory compliance, as regulatory compliance often mandates the use of multi-factor authentication to meet security standards and legal requirements. Two-step authentication is often not enabled by default and must be activated in account settings, which is why user education remains critical.

Multi-factor authentication (MFA) enhances security by requiring more than one method of authentication from independent categories of credentials. MFA protects personal data from being accessed by unauthorized third parties who may have discovered a single password.

Accounts with MFA enabled are significantly less likely to be compromised compared to those that rely solely on passwords. Since users tend to reuse passwords across multiple accounts, implementing MFA is especially important to reduce the risk of unauthorized access. Two-factor authentication can add an extra layer of security that protects users from hackers, especially as phishing attacks and social engineering techniques continue to rise.

MFA can be adaptive, providing flexibility in security based on the sensitivity of the data being accessed. Adaptive authentication adjusts the level of authentication required based on the risk associated with a particular action, such as logging in from a new physical location or accessing sensitive data.

Different MFA methods, such as email codes, authenticator apps, or biometric verification, can be chosen depending on the level of security required and user convenience.

The term "common mode" refers to the most widely used two-step authentication methods. According to industry standards, the most common two-step authentication methods include:

These methods are popular because they balance security and convenience for users across a variety of platforms and services.

Most users already have social media accounts and are familiar with using them for authentication, making social login a convenient and widely adopted MFA method. Social login allows users to authenticate using existing social media accounts, which typically includes additional security checks.

Many modern organizations combine these methods with passwordless authentication and identity-based access controls. Platforms like Everykey integrate seamlessly with IAM solutions and two-step authentication workflows by tying access to user presence and trusted devices, reducing reliance on easily compromised factors like passwords or SMS codes.

Note: Security questions can be used as a simpler form of multi-factor authentication but should not be the sole method of authentication.

Security Note: SMS and Email OTP are considered to be vulnerable to SIM-swapping attacks, making them less reliable for protecting high-value accounts.

Using an authenticator app is a safer method of two-step authentication compared to SMS or email codes. Authenticator apps generate verification passcodes that are not susceptible to SIM card swap attacks. During user attempts to log in, users are prompted to enter a code from their authenticator app to verify their identity.

Popular options include Microsoft Authenticator and Google Authenticator. These apps create randomly generated one time passwords that refresh frequently and do not rely on a mobile network connection.

Passkeys are rapidly adopted and replace traditional passwords with device-bound cryptographic credentials, often working alongside authenticator apps to improve security.

Modern versions of Push Notifications often include number matching to prevent accidental approvals and reduce MFA fatigue attacks. When logging in, users receive a notification on their device and must approve or deny the login attempt.

Biometric verification uses unique physical characteristics to verify a user's identity and is a growing method of authentication. Facial recognition and fingerprint scanning rely on biometric data that is difficult to replicate.

Biometric authentication provides a seamless experience for end users while still adding a strong layer of security. However, biometric data must be stored securely to protect user privacy and prevent misuse.

Hardware Security Keys are considered the gold standard for security because they are virtually immune to phishing and remote attacks. Security keys are physical devices used as a second authentication factor and are considered the strongest method of two-step authentication.

In addition to hardware tokens, software tokens are also commonly used. Software tokens are stored on general-purpose electronic devices such as computers or mobile phones and generate temporary authentication codes for two-step authentication.

Security keys provide a strong method of two-step authentication for online transactions and are often required for administrators or privileged users. These physical tokens may require additional hardware but dramatically reduce the risk of account compromise.

The mobile phone is one of the most common physical devices used in two step authentication. A verification code, push notification, or one time password is often sent directly to a registered phone number via SMS text message.

Text and call one-time passwords (OTPs) are delivered to a user’s registered mobile number for authentication purposes. While convenient, SMS text message and Email Codes are considered the least secure methods in 2026 because they are vulnerable to interception and SIM-swap attacks.

One-time passcodes can be delivered via text message or email as a method of two-step authentication. Email codes are a straightforward method of two-step authentication for online transactions and remain widely used.

Email codes are a common method of multi-factor authentication that requires users to enter a unique code sent to their registered email address. However, SMS and Email Codes are considered the least secure methods in 2026 because they are vulnerable to interception and SIM-swap attacks. Using the same password across multiple accounts further increases the risk, making two-step authentication even more important to protect your information.

A one time passcode serves as the second factor in many common authentication workflows and is often used as part of two step verification processes.

Magic links are a user-friendly authentication method that sends a unique link to a user’s email for direct authentication, though they should be used carefully for sensitive accounts.

The most common two-step authentication methods include:

SMS and Email Codes are considered the least secure methods in 2026 because they are vulnerable to interception and SIM-swap attacks. They are better than no protection, but not recommended for high-risk accounts.

Hardware security keys are considered the strongest method of two-step authentication because they are resistant to phishing and remote attacks.

Yes. Using an authenticator app is a safer method of two-step authentication compared to SMS or email codes because it is not vulnerable to SIM swapping.

Two-step authentication can significantly reduce the risk of unauthorized access to online accounts and is strongly recommended for email, financial services, cloud tools, and business systems.

Yes. Adaptive authentication adjusts the level of authentication required based on user behavior, device trust, and physical location.