Add Multifactor Authentication to Your Web and Mobile Apps

In today’s digital world, securing user accounts is more critical than ever. Cyberattacks are on the rise, and methods like SIM swapping have exposed vulnerabilities in traditional SMS-based authentication systems. While SMS is still a valid option for one-time passwords (OTPs), it should not be your sole defence against breaches.

This blog explores why implementing Google Authenticator and other multifactor authentication (MFA) methods is crucial for modern web and mobile apps, how they can mitigate the risks of SIM swapping, and how they can reduce operational costs in the long run.

Why SMS-Based Authentication Is Not Enough

SMS-based authentication, while widely adopted, has significant limitations:

• Vulnerability to SIM Swapping: Attackers can convince mobile providers to transfer a user’s phone number to a new SIM card, giving them access to OTPs sent via SMS.
• Increased Costs: Sending SMS messages, especially internationally, can quickly add up, impacting your bottom line.
• Delays and Unreliability: SMS messages can be delayed due to network congestion, frustrating users and increasing support queries.
• Dependency on Mobile Networks: SMS requires users to have active service, limiting its effectiveness for global or offline users.

Enter Google Authenticator and Multifactor Authentication

Google Authenticator and other time-based one-time password (TOTP) apps provide a more secure and cost-effective solution. Instead of relying on SMS, users generate time-sensitive codes directly on their devices, bypassing the need for cellular networks.

Benefits of TOTP-Based Authentication:

1. Enhanced Security:
   • TOTP codes are generated locally on the user’s device and are not transmitted over networks, making them immune to interception and SIM swapping.
   • Codes expire within 30–60 seconds, reducing the window for attacks.
2. Lower Costs:
   • No recurring SMS charges.
   • Elimination of international messaging fees for global users.
3. Improved Reliability:
   • TOTP codes work offline, ensuring accessibility even in areas with poor network coverage.
4. User Convenience:
   • Users can manage multiple accounts from a single authenticator app.
   • Many apps, like Google Authenticator, Microsoft Authenticator, and Authy, are widely used and trusted.

Other MFA Options to Consider

In addition to TOTP apps, consider implementing these methods for robust security:

• Push Notifications:
  • Send a prompt to the user’s registered device to approve or deny login attempts.
  • Highly user-friendly and secure as it ties authentication to a specific device.
• Biometric Authentication:
  • Leverage device features like fingerprint scanners, facial recognition, or retina scans.
  • Adds an extra layer of security without requiring additional hardware.
• Hardware Tokens:
  • Physical devices like YubiKeys offer unmatched security for high-risk accounts.
  • Ideal for enterprises handling sensitive data.

SMS for OTP: Still Relevant for Some Scenarios

While SMS should not be the sole method of authentication, it can still serve a purpose for:

• Backup Authentication: Providing SMS as a fallback option ensures accessibility for users without a smartphone.
• Temporary Codes: For users who need quick, one-time access, SMS OTP can act as an interim solution.

However, always combine SMS with other MFA methods to minimise risks.

How to Implement Google Authenticator and MFA in Your Apps

Here’s a high-level approach to adding MFA to your web and mobile apps:

1. Set Up TOTP Support:

• Use libraries like PyOTP (Python), Otp.NET (.NET), or Google Authenticator SDKs.
• Integrate TOTP generation and verification into your backend.
• Provide QR codes for users to scan with their preferred TOTP app during setup.

2. Enable Push Notifications:

• Use services like Firebase Cloud Messaging (FCM) or Apple Push Notification Service (APNS) for mobile apps.
• Ensure end-to-end encryption to protect notification data.

3. Integrate Biometrics:

• For mobile apps, utilise platform-specific APIs like BiometricPrompt (Android) and LocalAuthentication (iOS).
• On the web, consider WebAuthn, a browser API supporting biometric authentication.

4. Implement a Seamless User Flow:

• Guide users through easy setup processes, offering multiple MFA options.
• Provide fallback methods for account recovery, such as recovery codes or email verification.

Operational Cost Savings of MFA

Switching from SMS to MFA methods like Google Authenticator not only improves security but also reduces operational costs:

• Reduced Support Overhead: Fewer incidents of SIM swapping and delayed OTPs mean fewer support tickets.
• Elimination of SMS Fees: With TOTP apps, you save on the cost of sending SMS messages, especially internationally.
• Scalability: MFA solutions can scale effortlessly as your user base grows, without incurring significant additional costs.

Conclusion

In 2025, robust authentication is no longer optional—it’s essential. Transitioning from SMS to Google Authenticator and other multifactor authentication methods is a smart move for both security and cost-efficiency. By investing in MFA today, you protect your users from emerging threats like SIM swapping and position your business as a trustworthy platform.

If you’re looking to integrate Google Authenticator or multifactor authentication into your web or mobile apps, Digital One Agency can help. With our expertise in secure app development, we can customise MFA solutions tailored to your needs.

Contact us today at contact@digitaloneagency.com.au or call us at +61 2 9057 9079 to discuss your project.

Let’s build secure, user-friendly apps that users trust!