Arduino as bluetooth keyboard for phone

Hi All. I've appreciated your help in the past and I'm hoping someone can point me in the right direction. I have a camp that will be using RFID wristbands during registration and I would like to setup some battery powered devices that can be paired to smart phones to send the serial number of an rfid tag/band to a web form as a keyboard.

The battery, arduino, and RFID part is pretty simple, but I'm new to the world of arduino bluetooth and there seems to be a dizzying array of modules and types and I don't know where to begin.

What type of bluetooth module would be used for this application? Does anyone have any type of example project they could point me to?

You need a bluetooth module that is capable of the HID protocol. The cheapest way I know is to use the common HC05 module (~3$) and flash the RN-42 firmware to it.

The easy way is to just buy an RN-42 (~20$)

couka:
You need a bluetooth module that is capable of the HID protocol. The cheapest way I know is to use the common HC05 module (~3$) and flash the RN-42 firmware to it.

The easy way is to just buy an RN-42 (~20$)

I'm going the flash firmware route first. I figure why not. You need a computer with a parallel port. I don't think a usb to parallel converter will work. For posterity.

For posterity, here is the link to what we're talking about...