What is Two-Factor Authentication (2FA)?
Two-factor authentication, also known as 2FA, is an extra layer of security that requires not only a password and username but also something that only, and only, that user has on them, i.e., a piece of information only they should know or have immediate access to.
This extra ‘factor’ is in addition to traditional username and password access and means that in the event of one factor being compromised, an attacker still will not be able to access the account as they also need to bypass the second factor.
Key Takeaways
- Two-factor authentication (2FA) adds an extra layer of protection beyond just a password.
- It requires the user to provide two different forms of identification to gain access.
- The two factors can be something you know (like a password), something you have (like a code from an app), or something you are (like a fingerprint).
- 2FA makes it much harder for hackers to gain access to accounts, even if they manage to steal the password.
- Many major online services now offer 2FA as an optional security feature, and experts recommend enabling it whenever available.
- Setting up 2FA requires registering a secondary device like a mobile phone. A code is sent to this device during login.
- 2FA codes can be received via text, automated voice calls, app notifications, or hardware tokens.
- While inconvenient, 2FA provides effective protection against phishing, password theft, and other common attacks.
Two Factor Authentication Definition
Two-factor authentication is an extra layer of security that requires not only a password and username but also something that only, and only, that user has on them, i.e., a piece of information only they should know or have immediate access to.
This extra ‘factor’ is in addition to traditional username and password access and means that in the event of one factor being compromised, an attacker still will not be able to access the account as they also need to bypass the second factor.
How Does Two-Factor (2FA) Work?
Two-factor authentication works by requiring two different ‘factors’ – categories of credentials – to verify a user’s identity before they can gain access to an account or service:
- Knowledge factors: Something the user knows, such as a password or PIN.
- Possession factors: Something the user has, such as a security token, mobile phone, or authenticator app.
- Inherence factors: Something the user is, such as a fingerprint or other biometric identifier.
For example, to log into a bank account with 2FA enabled, a person would need to provide their username and password (knowledge factor) plus a numeric code displayed on their mobile authenticator app (possession factor).
Without access to that unique code, a cybercriminal cannot break into the account even if they have stolen the password somehow.
Why Use 2FA?
Two-factor authentication is highly recommended as an additional security layer by cybersecurity experts, as it provides effective protection against many common hacking techniques:
- Phishing: 2FA protects against phishing scams in which users are tricked into giving up login credentials. Even with credentials, access would be denied without the second factor.
- Password theft: Stolen, weak, or reused passwords are useless without control of the second factor registered to the real account owner.
- Brute force attacks: Automated login attempts are thwarted when the attacker does not have the secondary factor.
- Data breaches: Hackers with password databases from breaches are blocked from accessing accounts protected by 2FA.
While 2FA does create an extra step in the login process, the enhanced security is well worth the minor inconvenience for most users.
How to Set Up Two-Factor Authentication
Setting up two-factor authentication is a simple process that starts with registering a secondary device, such as a mobile phone, with the service provider. Here are the general steps:
Register Secondary Device
Most 2FA systems require a secondary device like a mobile phone or tablet to receive the second factor. This is typically done by:
- Providing the phone number to receive SMS/text messages
- Installing a dedicated authenticator app
- Syncing with another trusted device, such as another mobile or hardware token
This associates the device with the account as part of the 2FA process.
Enable 2FA
Within the account settings, the user enables 2FA and links the registered secondary device. The specific service provider provides step-by-step instructions.
The initial setup may involve scanning a QR code using the authenticator app or entering a secret key provided for account linking.
Configure 2FA Preferences
Some 2FA services allow users to configure preferences like:
- Default 2FA method (app, SMS, phone call, etc.)
- Backup verification methods
- Trusted locations that waive 2FA requirements
- Device pairing for simplified 2FA prompts
These options provide convenience while maintaining security.
Login with 2 Factors
Once enabled, subsequent logins will require verification via the second factor:
- Knowledge factor: Enter username and password as usual
- Possession factor: Approve prompt on mobile authenticator app or enter code received via SMS/phone call
Once confirmed, access is granted. 2FA prompts may be repeated periodically, even during an active session.
What are the Types of 2FA Verification Methods
There are several options for receiving the 2FA verification code during login. The most common methods include:
SMS Text Verification
- A one-time passcode is sent via automated text message to the user’s registered mobile phone.
- Simple and convenient option widely supported.
- Relies on text/cellular service availability.
Voice Call Verification
- An automated voice call reads the one-time passcode to the user over the phone.
- Convenience for users without texting plans.
- Relies on cellular service availability.
Time-based App Verification
- The user opens an authenticator app to view ever-changing verification codes.
- No reliance on cellular service.
- Considered more secure than SMS/voice verification.
Push Notification Verification
- The login prompts the authenticator app to display an approval request.
- The user confirms by tapping ‘Approve’ in the app.
- Convenient and simple for the user.
Hardware Token Verification
- The user reads the code displayed on a dedicated hardware token device.
- It’s the most secure 2FA option but less convenient.
- A service provider or third party may provide the device.
Biometric Verification
- The user confirms using fingerprint, facial, or other biometric data.
- Leverages built-in sensors on modern smartphones/laptops.
- Convenience versus security tradeoff.
The specific 2FA methods available and recommended may vary across different service providers.
What are the Pros and Cons of Two-Factor Authentication (2FA)
Like most security measures, two-factor authentication comes with both advantages and potential drawbacks:
Pros of 2FA
- Stronger account security: The main benefit is improved protection against hacking.
- Wide availability: Common feature across most major providers.
- User convenience: Simple verification via mobile devices.
- Reduced liability: 2FA may limit losses in the event of fraud.
- Industry compliance: Meets cybersecurity regulations in some sectors.
Cons of 2FA
- Inconvenience: An extra step is required during the login process.
- Dependency: Reliance on secondary device availability.
- Limited support: Not universally implemented across all services.
- SMS costs: Potential text messaging fees with some providers.
- Setup: Initial activation may seem complicated to less tech-savvy users.
- Biometrics: Vulnerabilities exist, like device spoofing.
Examples of 2FA Implementation
Many major online services now provide two-factor authentication options:
Email Providers
- Gmail
- Yahoo Mail
- Outlook/Hotmail
- iCloud Mail
Social Networks
Financial Services
- Chase
- Bank of America
- Wells Fargo
- American Express
Online Retailers
- Amazon
- eBay
- Walmart
- Target
Cryptocurrency Exchanges
- Coinbase
- Binance
- Kraken
- Gemini
Cloud Storage
- Dropbox
- Google Drive
- OneDrive
- iCloud
The specific 2FA login process varies across providers but generally follows the same principles. Users are strongly encouraged to enable extra authentication for important online accounts whenever feasible.
Is 2FA Mandatory?
For most consumer services, two-factor authentication remains an optional extra security feature that users can enable if desired. However, 2FA is becoming mandatory for certain services or user types:
Work Accounts
Many corporations now enforce 2FA as a standard policy across all employee accounts to protect business data. Workers are required to enable secondary verification.
Government Accounts
Accounts associated with government services often require 2FA by policy. For example, all IRS online accounts mandate extra user authentication.
High-Risk Users
Providers may force high-risk users, such as those who have recently changed passwords or recovered from lockouts, to use 2FA as a protective measure.
High-Transaction Accounts
Financial institutions may require users to enable 2FA when conducting high volumes of sensitive transactions, such as wire transfers.
Cryptocurrency Accounts
Due to the irreversible nature of cryptocurrency transactions, crypto exchanges universally mandate 2FA for all users.
So, while still optional for general consumer accounts, mandates are increasing for accounts deemed high-value, high-risk, or containing sensitive data. Expect 2FA requirements to continue expanding in both the public and private sectors.
What are the Limitations of 2FA
While highly effective against common threats like phishing and password theft, two-factor authentication does have limitations:
- Account recovery attacks: 2FA cannot prevent the takeover of accounts via compromised recovery methods.
- SIM swapping: Attackers may hijack phone numbers to intercept 2FA verification messages.
- Social engineering: Users can still be manipulated into approving rogue 2FA login requests.
- Supply chain attacks: Compromised 2FA hardware/software vendors undermine security.
- User errors: Mistakes like reusing 2FA secrets or losing devices can also lead to account breaches.
Proper account hygiene, such as using unique recovery credentials and scrutinizing verification prompts, is still essential. 2FA alone cannot fully prevent all possible attack vectors. A combination of security measures is ideal.
Best Practices for 2FA
To gain the most security value from two-factor authentication, users should follow these best practices:
- Enable 2FA for important accounts whenever available. Prioritize financial, work, and email logins.
- Use a dedicated authenticator app rather than less secure SMS/voice verification if possible.
- Maintain control of registered mobile devices. Never share 2FA credentials.
- Carefully check verification details like the sender’s name to avoid approving fake login requests.
- Keep mobile OS, apps, and hardware tokens fully updated to address vulnerabilities.
- Use strong, unique passwords and credential recovery options to prevent account takeover.
- Take advantage of hardware security keys for high-value accounts when feasible.
The Future of 2FA
Expect even wider implementation of two-factor authentication as users and providers recognize its security advantages against increasingly sophisticated cyber attacks:
- More service providers will make 2FA mandatory, especially for enterprise accounts, government agencies, and high-value transactions.
- Authentication methods will move towards more advanced biometrics like facial recognition and fingerprint scanning.
- Transparent authentication will dynamically analyze user behavior patterns behind the scenes to silently confirm identities.
- Security keys and browsers may replace mobile apps for more convenient 2FA hardware integration.
- Regulation may force wider 2FA adoption, as happened in European financial services.
Final Thoughts
Two-factor authentication has become an essential security tool by adding a critical second layer of identity confirmation beyond just static passwords. While no single solution is impenetrable, 2FA provides effective protection against many of the most common intrusion techniques. As hacking attacks grow more advanced, users should adopt defensive measures like 2FA to help thwart unauthorized account access and fraud.
Frequently Asked Questions About 2FA
What happens if I lose my 2FA device?
Most providers give users backup 2FA methods like printed security codes or alternate phone numbers. You can use these to recover access and reset your 2FA credentials.
Is 2FA the same as multi-factor authentication (MFA)?
Yes, Multi-Factor Authentication is a more general term referring to any login system requiring multiple factors, which usually means two. 2FA is technically a form of MFA.
Does 2FA protect against phishing?
Yes. Because phishing relies on stealing user credentials, 2FA blocks access even if you are tricked into giving up your password. It requires the second factor only you possess.
What if I don’t have a smartphone for 2FA?
Most providers support 2FA via voice call, text message, email, or hardware tokens without needing a smartphone specifically. Mobile authenticator apps are just the most convenient and secure option.
Does 2FA drain my phone battery?
The impact is negligible: authenticator apps only activate briefly during actual login attempts. You’re not constantly using extra battery power just by having 2FA enabled.
What if I frequently switch between devices?
Some authenticator apps support cloud syncing or exporting your 2FA keys to transfer between multiple registered devices. Or you can use hardware keys that work universally across different phones, tablets, and computers.
Isn’t SMS 2FA still better than just a password?
Yes, SMS is still far more secure than relying on passwords alone. However, app-based 2FA is considered safer than text or voice verification, so it would be preferable if that option were available. Any 2FA is better protection than none.
Priya Mervana
Verified Web Security Experts
Priya Mervana is working at SSLInsights.com as a web security expert with over 10 years of experience writing about encryption, SSL certificates, and online privacy. She aims to make complex security topics easily understandable for everyday internet users.
