There have been multiple SIM swap complaints in the country over the years. The unfortunate part is that it leads to more losses than fraud alone. In most cases, fraudsters may drain your account even without knowing the password and hijacking your phone number. This is where device binding comes into the picture. It’s almost like locking your home with a password and a physical key that is possessed only by you. So, no one can break in even when they get access to your door code.
How Does Device Binding Work?
Device binding is a process that connects a particular application, say a UPI app, to a specific device only. That means the app will work only on this registered device and nowhere else.
This method has been already adopted by several apps like Google Pay and PhonePe. They do not just stop at checking your password or OTP. The app also analyzes whether it’s the same registered device you have been operating on for a long time.
They may even block your access if they do not get proper validation.
This is the best permanent factor of authentication to protect your account if a fraudster accesses your login credentials or password.
What Are the Types of Device Binding Methods?
Banking apps for personal loans and other requirements may implement multiple device binding methods, but the common ones are:
Cryptographic Key Binding
This is a hardware-backed method that uses the iOS secure enclave or the android key store to generate and store several private keys. These keys always remain physically locked in tamper-proof hardware, so no one can extract them without verification. In short, it provides cryptographic proof of attestation.
SIM Card Binding
This device binding method generally combines authentication to a mobile number’s presence on a device. However, it is still a vulnerable method and doesn’t do much in terms of SIM swap attacks. In most cases, it has to be combined with hardware-backed device binding methods for better security.
Device ID Binding
This binding technique uses specific identifiers like Android ID or IDFV (iOS). However, fraudsters may use hooking frameworks or device cloning to spoof this method at times. That means hooking frameworks that modify app behavior at runtime can make it quite vulnerable over time.
Token-based Binding
This device binding method always depends on software-generated tokens that are stored in a particular device. The only catch is that you can easily extract and replay the tokens across multiple devices.
How Does Device Binding Work in Banking Apps?
Device binding often operates through a defined sequence across any UPI app or general banking application. This involves the following:
- Registration
- Per-session Validation
- Transaction Signing
Here’s an overview:
The Initial Handshake or Registration
Your app generates an asymmetric key pair (public + private) using the device’s Trusted Execution Environment once you install it on your device. It sends the public key only to the bank’s backend server, which stores it in the same user’s account. However, the private key never leaves your device.
Several advanced implementations combine the same key with SIM binding in a way that the physical device and the verified mobile number must match during registration.
Per Session and Transaction Validation
The app signs a request payload with the private key stored on your device when you open it or initiate a transaction. The backend uses the stored public key to validate the same signature.
The access is generally denied before the proceeding of any transaction if the signature fails. That’s because the request will always originate from a different device without the private key.
Sometimes, a correctly intercepted token may seem useless on a different device because replaying it without a private key signature fails the validation.
What Can You Achieve With Device Binding?
A backend service will always consider device identity as a mandatory factor across all transactions. That means it will not depend only on user credentials or phone number possession. So, any access attempt that you make from an unbound device is blocked at the authentication layer. That means you cannot indulge in any activity and things stop before any transaction can be processed.
This creates a particular security architecture where:
- Credentials verify identity and showcase who you are
- Device binding verifies possession, especially regarding what you have
- You can replicate the same combination without physical access to the original device
Device Binding: The Best Way to Avoid Payment Fraud
Device binding is something that goes beyond payment because it defeats the SIM swap attack chain directly. Even if the attacker is able to port your contact number and get the OTP, they will be operating from an unbound device. So, the banking app’s backend will always request the request because there is no valid signature to show from your private key which is available only on your device.