The largest complaint I have with the current edition YubiKey (which is an awesomely useful and simple product; limited-scope task-specific devices FTW) is the form factor and seeming complexity of capacitive contact sensors. Another device I use (though wouldn't recommend unless you really, really need it due to the cost) is a GoldKey, which has what I would consider to be the perfect form-factor.
There are several reasons why this form-factor is better than the current version:
- The current version does not contact the USB pins in the port securely. If any upwards pressure is applied to my key, it disconnects.
- The key has a large surface area, albeit thin. The large surface area and thinness makes right where the key is inserted into the USB port a major stress point where excessive downwards pressure could cause damage.
- The current key requires almost no pressure to remove as it can not utilize the built-in retention spring clips present in most USB ports. The GoldKey I have fits quite snugly, and snaps in and out cleanly.
Attached are two pictures; one of the device itself, the other of the device inserted into a computer with the stock keychain. My idea for a YubiKey would be to utilize this form-factor with one of two positions for the ground-bridge contact sensor: the back as a protruding pin or surface-run wire (exposed epoxy on the GoldKey) or as a 'floating' 3mm x 3mm panel cut out of the top surface of the key.
Attachment:
goldkey-security-key1.jpg
Attachment:
goldkey-security-key2.jpg
The circuit necessary to detect finger presses on a grounded panel to the contact panel should be simpler, I think, than the pressure-sensitive capacitive system currently in use.
The dimensions are: 30mm long, 12mm wide, 4.5mm thick. (The dimensions of an elongated USB plug.)
My 2¢,