3 ms·

I worked for a company that made these. We sold expensive software to the FBI. Took about six months for someone to crack the hash.

deepserket 5mo ago
What about a system that saves in some way the hash in a Blockchain, and if you, eg, XOR the hash of the video with the hash of the previous block you will "certainly" know that the video was created between the previous block and the block where the hash is saved in. That's a starting point.
- ChrisMarshallNY 5mo ago
  Might have a point. This was before blockchain. I suspect that the cops wouldn’t like the chain public, though.
  - Terr_ 5mo ago
    Like when people discuss voting, I believe a blockchain [0] is a terrible pitfall compared to a classic distributed database system of predefined nodes run by different organizations. For example, imagine a couple hundred predefined nodes run by different states, federal agencies, etc. An attacker altering the ledger would still require compromising an unreasonably large number of independent groups at once, and even then the rest would be able to clearly see that some unusual and suspicious event occurred. By limiting membership a bunch of problems simply vanish, like long-clearing times, wasting hardware on mining, vulnerability to foreign botnets, etc. [0] A blockchain is distinguished by its core requirement, from which a cascade complexity flows: Uncontrolled node membership. Don't be fooled by people pitching "private blockchain", its a contradiction in terms designed to rehabilitate hype, like "multi-sample Theranos test" or a bicycle as "Segway passively stabilized inline wheel model."
    - girvo 5mo ago
      You just described IBM's whole Hyperledger Fabric thingy. I worked with it once upon a time, with the biggest insurance companies in my country where they plus a regulator all ran nodes.
- deleted 5mo ago
  [deleted]
- mcapodici 5mo ago
  This sort of chain doesn't need PoW I take it, just a very secure police server to sign blocks.
  - inigyou 5mo ago
    And it couldn't be run by the police or any of their friends, since they're the adversary.
- dindunuf 5mo ago
  that does nothing to verify authenticity
  - teravor 5mo ago
    it does something, sometimes. it pushes the required fabrication timeline back. if it is mandated that every photo or video taken for the possible use in evidence is notarized at the time of acquisition, any fabrication would necessitate total premeditation. that is, the fabricators would need to know ahead of time what they were pursuing and what evidence they would need. this seems like a very costly barrier. for example, altering security footage would require some fantastical elements: a real-time system of ingesting real footage and altering it in real-time to slip it into the notarization pipeline within the error margins. requiring that any equipment that produces acceptable evidence stream commitment hashes in real-time to public append-only repositories would be an enormous step forward.
lostlogin 5mo ago
Now sell them version 2.
EPWN3D 5mo ago
"Crack the hash"? Does this mean you were employing some novel hashing algorithm and relying on its secrecy? If so your employer were never serious about security in the first place. Hardware attestation is more or less a solved problem, and that solution does not involve secret algorithms.
- ChrisMarshallNY 5mo ago
  Eh. It was some kind of hash of the image. I was not involved in that project, so can't tell you exactly how it worked, but the images were "signed," and someone figured out how to "re-sign" an altered image. I think it was a fairly well-known technique.
  - XorNot 5mo ago
    Which still sounds like your employer was simply incompetent because why was any type of perceptual hashing scheme even involved? Signing digital data with hardware secure tokens is a commodity capability in the iPhone many of HNs users are reading this site with.
    - dzhiurgis 5mo ago
      I think this has been around for not so long https://en.wikipedia.org/wiki/Content_Authenticity_Initiative https://en.wikipedia.org/wiki/Content_Authenticity_Initiativ...
      - XorNot 5mo ago
        Sure but conceptually no one should've been able to crack any hashing scheme anyone half-way decent at their job could come up. SHA256 is the default and it's unbroken. Even SHA1 has scant few known collisions. So like...what the heck were they hashing and how that anyone was able to crack it?
        phreeza 5mo ago
        Maybe its more like the hash was a well known secure hash but someone managed to extract the salt/private key/signing certificate from the camera?

deepserket 5mo ago

What about a system that saves in some way the hash in a Blockchain, and if you, eg, XOR the hash of the video with the hash of the previous block you will "certainly" know that the video was created between the previous block and the block where the hash is saved in. That's a starting point.

ChrisMarshallNY 5mo ago
Might have a point. This was before blockchain. I suspect that the cops wouldn’t like the chain public, though.
- Terr_ 5mo ago
  Like when people discuss voting, I believe a blockchain [0] is a terrible pitfall compared to a classic distributed database system of predefined nodes run by different organizations. For example, imagine a couple hundred predefined nodes run by different states, federal agencies, etc. An attacker altering the ledger would still require compromising an unreasonably large number of independent groups at once, and even then the rest would be able to clearly see that some unusual and suspicious event occurred. By limiting membership a bunch of problems simply vanish, like long-clearing times, wasting hardware on mining, vulnerability to foreign botnets, etc. [0] A blockchain is distinguished by its core requirement, from which a cascade complexity flows: Uncontrolled node membership. Don't be fooled by people pitching "private blockchain", its a contradiction in terms designed to rehabilitate hype, like "multi-sample Theranos test" or a bicycle as "Segway passively stabilized inline wheel model."
  - girvo 5mo ago
    You just described IBM's whole Hyperledger Fabric thingy. I worked with it once upon a time, with the biggest insurance companies in my country where they plus a regulator all ran nodes.
deleted 5mo ago
[deleted]
mcapodici 5mo ago
This sort of chain doesn't need PoW I take it, just a very secure police server to sign blocks.
- inigyou 5mo ago
  And it couldn't be run by the police or any of their friends, since they're the adversary.
dindunuf 5mo ago
that does nothing to verify authenticity
- teravor 5mo ago
  it does something, sometimes. it pushes the required fabrication timeline back. if it is mandated that every photo or video taken for the possible use in evidence is notarized at the time of acquisition, any fabrication would necessitate total premeditation. that is, the fabricators would need to know ahead of time what they were pursuing and what evidence they would need. this seems like a very costly barrier. for example, altering security footage would require some fantastical elements: a real-time system of ingesting real footage and altering it in real-time to slip it into the notarization pipeline within the error margins. requiring that any equipment that produces acceptable evidence stream commitment hashes in real-time to public append-only repositories would be an enormous step forward.

lostlogin 5mo ago

Now sell them version 2.

EPWN3D 5mo ago

"Crack the hash"? Does this mean you were employing some novel hashing algorithm and relying on its secrecy? If so your employer were never serious about security in the first place. Hardware attestation is more or less a solved problem, and that solution does not involve secret algorithms.

ChrisMarshallNY 5mo ago
Eh. It was some kind of hash of the image. I was not involved in that project, so can't tell you exactly how it worked, but the images were "signed," and someone figured out how to "re-sign" an altered image. I think it was a fairly well-known technique.
- XorNot 5mo ago
  Which still sounds like your employer was simply incompetent because why was any type of perceptual hashing scheme even involved? Signing digital data with hardware secure tokens is a commodity capability in the iPhone many of HNs users are reading this site with.
  - dzhiurgis 5mo ago
    I think this has been around for not so long https://en.wikipedia.org/wiki/Content_Authenticity_Initiative https://en.wikipedia.org/wiki/Content_Authenticity_Initiativ...
    - XorNot 5mo ago
      Sure but conceptually no one should've been able to crack any hashing scheme anyone half-way decent at their job could come up. SHA256 is the default and it's unbroken. Even SHA1 has scant few known collisions. So like...what the heck were they hashing and how that anyone was able to crack it?
      - phreeza 5mo ago
        Maybe its more like the hash was a well known secure hash but someone managed to extract the salt/private key/signing certificate from the camera?