Apple

We want to design a Blood Pressure monitor which meets the Continua Health Alliance Requirement. And we develop the app with iOS6.1.3 and iOS7.

Continua means we need comply “Blood Pressure Profile” (write as BLP followed) base on Bluetooth GATT work on BLE.

But there is something conflicting between “BluetoothDesignGuidelines R6.pdf” (write as Guideline followed) and BLP. It is about the pair and bond.

First question：

According to the Guideline (see Appendix A for detail), the Peripheral should reject the ATT request using the Insufficient Authentication error code. By this way, the Apple product can pair and bond with accessory.

But the BLP(see Appendix B for detail) asks the Peripheral to use the SM Slave Security Request procedure, if the peripheral uses bonding.

So the conflict is the method of triggering pairing and bonding.

I do like this:

When the peripheral received an ATT read request of characteristic, the peripheral judges whether the link is encrypted or not, if the link isn’t encrypted, the peripheral will send a SM Slave Security Request and reject the ATT request with “Insufficient Encryption” error code. It works well, and the Apple product does pair and bond with the accessory successfully. But this method is not mentioned explicitly in the “BluetoothDesignGuidelines R6.pdf”, and will it be OK to use this method in the future? Will Apple still allow do this in the future?

Appendix A:

In the “BluetoothDesignGuidelines R6.pdf”, we found that:

Pairing

The Bluetooth accessory should not request pairing. If, for security reasons, the accessory requires a bonded relationship with the Central, the Peripheral should reject the ATT request using the Insufficient Authentication error code, as appropriate. See specification, Volume 3, Part F, Section 4 for details.

As a result, the Apple product may proceed with the necessary security procedures.

Appendix B:

In the “Blood Pressure Profile”, we found that:

6.1 Blood Pressure Sensor Security Considerations

All supported characteristics specified by the Blood Pressure Service shall be set to

Security Mode 1 and either Security Level 2 or 3.

The Blood Pressure Sensor should bond with the Collector.

The Blood Pressure Sensor should use the SM Slave Security Request procedure to

inform the Collector of its security requirements. If the Blood Pressure Sensor uses

bonding, it shall use the SM Slave Security Request procedure.

All characteristics specified by the Device Information Service that are relevant to this

profile should be set to the same security mode and level as the characteristics in the

Blood Pressure Service.

Second question：

The Blood Pressure monitor is a slave and the Apple product is a master. We test on iOS 6.1.3.

If we use the pairing method comply with “BluetoothDesignGuidelines R6.pdf”, it really works well after pairing and bonding. But after I selected “Forget this device”, the iOS cannot pair and bond with my BLE device anymore. In addition, the slave also could not know the iOS has forgot it.

When I debug the slave’s pairing and bonding procedure, I find that even the iOS has forgot this device, the slave can still use the old IRK resolving the new random device address into the Apple product’s public device address, so, the slave considers itself is still in the bonding status. And because the iOS had forgot this device, the iOS did not encrypted the link. In this case, when the slave received an ATT read request of characteristic, the slave shall reject this ATT read request with the “Insufficient Encryption” error code, because the slave still ask a encrypted link. However, the iOS does nothing to process this error code.

We also test on iOS 7 beta(11A4414e), there is no problem anymore. Does there any way to resolve on 6.1.3, and will 7.0 or later could keep the status in beta version?