why is there a crypto dongle on pi camera v2 ?

3 posts
by Frederir » Wed May 25, 2016 8:12 pm
The Raspberry Pi ecosystem is wonderful, having an open GPU with documentation is invaluable. Of course there is limitations CSI and DSI port are not really open and the closed ISP limit the choice of sensor usable for camera.

The new camera based on Sony IMX219 could be really good, we could regret the small size of the sensor as it is only 1/4"but sensibility problems can be dealt with more light. There is hacks to replace the standard lens with custom mount but the mechanical construction of the Camera PI V2 will not allow for high quality mechanical fit between the sensor and a custom lens holder.

What we could have expected is third parties camera module with CS mount or M12 mount, custom camera modules with integrated flex for the Pi zero etc... but it wont happen.

It wont happen because there is a crypto dongle on the camera board, and the closed source firmware check the dongle each time the camera is used. The dongle is a ATSHA204A from Atmel and the implementation is secure (nonce + hmac).
This feature was not announced with the press release of the Pi Camera V2, and I'm sad to discover it.

I understand the crypto dongle is here to prevent third parties camera board to reach the market, what I don't understand is why Raspberry Foundation wants to prevent third parties cameras. Can someone from the foundation explain it to us ?

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by gordon77 » Wed May 25, 2016 8:36 pm
.... the mechanical construction of the Camera PI V2 will not allow for high quality mechanical fit between the sensor and a custom lens holder...

Why is that different to the v1 camera?
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by jdb » Wed May 25, 2016 8:40 pm
The camera module is a revenue stream that feeds into the Foundation. What people don't realise when making cloned products is that this diverts money into knock-off merchants' pockets rather than our licenced distributors (for which we take a licence fee).

Camera module production isn't a case of designing a PCB, running it through EMC and saying "that'll do" - a substantial engineering effort is spent in getting the sensor matched to the ISP tuning stages to produce acceptable images in the full gamut of lighting conditions, which turns out to be more art than science. This engineering time spent by RPTL represents a significant expenditure that cannot be recovered if clones appear on the market a week after the official release.

If the CSI peripheral were opened up (which is a function of Broadcom being willing to document the peripheral openly) then there would be nothing preventing embedded-ISP cameras from being used on Pi. As it is, the ISP and CSI peripherals are not publicly documented so a whitelist of bayer-mode cameras are the only ones that will work.

So, to reiterate: the arguments for adding crypto to the camera are the same as ensuring that manufacturers under a licence agreement are the only ones allowed to produce Raspberry Pis.
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