Bluetooth Secure Simple Pairing (SSP) using QR code as Out of Band (OOB) channel

Bluetooth Secure Simple Pairing (SSP) using QR code as Out of Band (OOB) channel

Bluetooth Secure Simple Pairing (SSP) is a security protocol used to establish a secure connection between two Bluetooth devices. It uses a combination of passkeys and confirmation codes to prevent unauthorized pairing.

Out-of-band (OOB) pairing is a method of exchanging pairing information outside of the Bluetooth radio channel. This is typically used to overcome limitations with pairing in challenging scenarios like:

• When the user cannot easily read or enter a passkey, such as when the devices are far apart.
• When the devices are unable to communicate directly with each other over Bluetooth due to interference.

QR codes offer a convenient and secure way to implement OOB pairing.

How it Works

Here’s the process of using QR codes for SSP pairing:

1. Device Initialization: Both devices initiate the pairing process.
2. QR Code Generation: One device generates a unique QR code containing the necessary pairing information. The information can include a numerical passkey, a confirmation code, or a combination of both.
3. QR Code Display: The device displays the QR code on its screen or transmits it to another device that can then display it.
4. QR Code Scan: The other device scans the QR code using its camera. This action decodes the pairing information.
5. Confirmation: The user on the receiving device can confirm the pairing process either by entering the passkey or by accepting the confirmation code.
6. Secure Connection: Upon confirmation, the two devices establish a secure Bluetooth connection.

Advantages

• Enhanced Security: QR codes are tamper-resistant and prevent unauthorized modifications, contributing to improved security.
• User-Friendliness: Scanning a QR code is significantly easier than manually entering passkeys, especially for complex numbers.
• Broad Compatibility: Most modern smartphones and tablets are equipped with QR code scanners, making it widely accessible.

Comparison with other methods

Implementation

Implementing QR code-based OOB pairing requires specific Bluetooth libraries and QR code generation tools.

Code Example (Conceptual):

// Generate a unique QR code containing the pairing information
let qrCodeData = generatePairingInformation();
let qrCode = generateQRCode(qrCodeData);

// Display or transmit the QR code to the other device
displayQRCode(qrCode);

// Scan the QR code on the other device
let scannedData = scanQRCode();

// Verify the pairing information and establish a secure connection
verifyPairing(scannedData);
establishSecureConnection();

The specific implementation will vary depending on the chosen Bluetooth library and the platform.

Conclusion

Using QR codes as an OOB channel in Bluetooth SSP offers a secure and user-friendly alternative to traditional passkey-based methods. This approach enhances the security of Bluetooth pairing and improves the overall user experience.