[HN Gopher] Attested Audio with ZKP
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       Attested Audio with ZKP
        
       Author : rpruiz
       Score  : 20 points
       Date   : 2023-06-21 05:24 UTC (1 days ago)
        
 (HTM) web link (ddkang.github.io)
 (TXT) w3m dump (ddkang.github.io)
        
       | Adrox wrote:
       | I don't understand how this avoids any simple attack both for
       | audio or video:
       | 
       | - Alter/manipulate the audio/video has much as you want.
       | 
       | - Play it.
       | 
       | - Have a "attested" microphone/video recording the "manipulated
       | audio/video".
       | 
       | For video maybe you can actually try to prove that's recording a
       | screen not the real event, but seems much harder for audio, you
       | can just say the echos/ distortions came from the environment...
        
         | mindslight wrote:
         | It doesn't. It's called the "analog hole" and has caused much
         | head shaking with regards to the media cartels' attempts at
         | digital restrictions management on the output side.
         | 
         | Trying to secure that regime on the input side would seem to be
         | even more fraught with problems. At least using the analog hole
         | for the output side causes quality degradation from reencoding
         | the content (the most common goal is digital redistribution).
         | Whereas on the input side, the content begins in the digital
         | domain so it's not even adding an extra analog step.
        
         | kobalsky wrote:
         | I think in this case the point would be to trust the source
         | publishing the audio and not content.
         | 
         | I cam see a gpg like registry where news stations publish their
         | public keys to verify that their audio / video snippets have
         | not been tampered with.
        
           | ssfrr wrote:
           | Yeah, this is my understanding also. I don't understand how
           | this is better than the publisher signing the content with
           | their own key though, rather than relying on a special
           | microphone.
           | 
           | I wish the article was more clear on what threat model
           | they're trying to address.
        
       | JanjuaThala wrote:
       | [flagged]
        
       | ssfrr wrote:
       | > In our setting, we can compute a function that computes the
       | hashes of the inputs and outputs the edited audio from the
       | inputs. By revealing the hashes, we can be assured that the
       | inputs match the recorded audio!
       | 
       | I don't understand how this works, or what exactly is being
       | proven here. For instance, you could silence the given inputs and
       | inject some other unrelated audio, so the fact that your output
       | hash incorporates the input hashes doesn't seem very meaningful.
       | 
       | I figure I must be missing something here.
        
       | lionkor wrote:
       | > The hardware manufacturer can destroy the private key after it
       | is placed on the device. By doing so, the private key is
       | inaccessible!
       | 
       | I'm pretty sure the private key is very accessible, if it's used
       | at runtime which it is. Just not easily.
        
         | flangola7 wrote:
         | Extracting the private key out of a modern HSM enclave is
         | essentially impossible for anything less than NSA-level
         | capabilities.
        
         | didntcheck wrote:
         | Yeah. People have been hoping for a signed "Photoshop-proof
         | camera" since digital image manipulation was invented, but it
         | has the same limitations as any form of DRM. It only slows
         | people down a bit. There's also the analog hole - i.e. just
         | stick your "attested" microphone in front of a speaker
        
           | kj4ips wrote:
           | Canon tried to do this with their ODD system, and they got
           | kinda close, but it is possible to extract the key from a
           | given camera, and forge signatures.
           | 
           | Their verification system also seems to include a smartcard
           | or SD card-like thing (which might be doing something
           | special, or might just be DRM)
        
           | lionkor wrote:
           | or rip out the wires and attach whatever speaker you want,
           | not really detectable
        
             | flangola7 wrote:
             | It is detectable if the other components are
             | cryptographically paired, like they are in newer iPhones.
             | 
             | Go try to swap a camera or screen between two identical
             | iPhone models, it won't work.
        
       | noodlesUK wrote:
       | I would say there is a better way of doing this. In the forensic
       | community it has been long known that audio can be timestamped
       | and fingerprinted by the 50/60hz electrical hum in the
       | background. In many countries this hum is recorded so it can be
       | used later as evidence.
       | 
       | Unless counter-forensics are applied, AI audio is not going to
       | have the right hum.
       | 
       | It's not cryptographically secure, but it gives good assurance
       | and doesn't require tamper resistant hardware (which makes the
       | cryptographic security dependent on how secure the resident keys
       | are)
       | 
       | https://en.m.wikipedia.org/wiki/Electrical_network_frequency...
        
         | CGamesPlay wrote:
         | But isn't it really easy to apply those counter-forensics? It
         | seems like it's much easier to fake a hum on a digitally
         | created audio file than to change or remove the hum from
         | existing file.
        
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       (page generated 2023-06-22 23:03 UTC)