[Cryptography] Best internet crypto clock

Natanael natanael.l at gmail.com
Tue Oct 7 14:50:56 EDT 2014

Den 7 okt 2014 20:41 skrev "Arnold Reinhold" <agr at me.com>:
> This conundrum suggests a need for a camera that cryptographically signs
its images. It could be packaged and certified as a FIPS-140 level 4 HSM.
The camera would have a built-in asymmetric key pair with the public key
available from the manufacturer by camera serial number. It might also
accept additional keys via Bluetooth or USB and sign images using those
keys as well. As with any HSM, secret keys would be erased upon detection
of tampering. The camera could communicate via Bluetooth or USB or an
optical link and be controlled by a cell phone app, perhaps clipping onto
the cell phone or phone case. It might use inductive charging to minimize
electrical connections.
> I would envision including a good quality internal clock, set at time of
manufacture and non alterable. (When the clock battery dies, the camera is
toast.) The camera would periodically or on command output a signed
certificate containing the current reading of its internal click and maybe
an external nonce like the NIST beacon, which might then be sent to a time
stamping service, creating a record of internal clock drift over time.. The
camera might store a correction factor, so it could output a UTC time, but
the internal clock would be included in any certificate as well.

This approach is still limited. The camera can only attest to what color
values for each pixel it captured, not what really happened.

A very precisely color calibrated HDR display setup can likely fool most
cameras, or why not just a proper stage set up by theater / movie prop
designers, with heads of wax and all. Harder to fake video, but something
convincing can probably be made with face masks.

Light field cameras like lytro could be harder to fool due to the vastly
greater amount of information captured, but they still can't reveal a good
stage being fake.
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