Digital Camera Image Verification 255
Polo writes "While reading dpreview, I noticed that among several new products, Canon has announced a Digital Image Verification Kit to prove that an image taken by a particular camera has not been modified. It's disturbing to think about the conditions that would allow digital images to be accepted in a courtroom. I guess one defense would be to figure out how to 'verify' a photo of shark attack..."
Re:Canon (Score:1, Informative)
But I do agree with your general sentiment about open non-proprietary flash formats.
Re:It's called MD5 (?) (Score:5, Informative)
Well, the camera is only one step in the chain. Are they going to keep a bunch of these presumably more expensive memory cards lying around, or are "they" going to archive them on a CDR or hard drive? Once the image is out of the card, the verification is meaningless (if it wasn't already meaningless in the first place).
I provide "expert testimony" in court on a semi-regular basis in a completely different field. I always submit "photostatic replicas" of original documents and sign a notarized affidavit of their authenticity. Overall, it is simply the sworn testimony of the authenticity of any evidence that holds more weight than some "technological solution."
Photoshoppers be dammed! Long live fark.com
Re:won't work (Score:5, Informative)
GnuPG's ElGamal signing keys compromised (2003-11-27)
A severe problem with ElGamal sign+encrypt keys has been found. This leads to a full compromise of the private key.
Still does not (Score:5, Informative)
This is just general, but there are many rules about entering photograghs and other documents.
Re:2D autocorrelation... (Score:5, Informative)
Forget it. Only amateurs copy/paste regions and leave them like that. Those who alter images to produce really credible results may copy/paste bits of images at first, but then will blur/sharpen/solarize/burn/lighten/brush slightly part of them, drop some noise in them to match the pizelization of an original jpeg for example, merge several together and modify gradiants to make the final patch blend in just right in the bit of background you want to mask or change. The final resulting altered regions usually doesn't have much to do with the original bits you copied.
Re:won't work (Score:2, Informative)
None of that is to say that I think Canon's solution sounds very workable. So it embeds a hash in the image and uses that to detect if the image has been changed? So? I can do that already by hashing images as I import them. I don't understand how it prevents re-hashing, either. Besides, who cares if you can verify the digital file? It still has to be printed out at least once if it's going to be used in court. I don't know about you guys, but I know my GIMP printer drivers allow for all kinds of filters to be used on the print stream itself. Not only could I intercept and alter the data as it's being printed, but I don't see how you can verify that the printout comes from a verified file.
Re:Canon (Score:3, Informative)
He's taling about COMPACTFlash cards, which are a whopping 36.4(L) x 42.8(W) x 3.30(T) mm for the type-I's
Any smaller physical size for your media and you tend to lose them. A lot.
"honey, have you seen my postage-stamp sized SD card?"
"I think one of the kids snapped it in half when they tried to feed it to the cat."
"Oh that's ok, it was only 75 bucks (sob)"
Re:Courtroom.Rules of evidence (Score:3, Informative)
All writings and papers and so forth have to be introduced in such a way as to either not be hearsay or to gain a hearsay exception.
I don't know why you might think that a video movie is more sacrosanct than something like a blood sample. Both require someone to testify about them and in both cases the person can convict someone simply by lying.
By the way---remember the video in the Microsoft trial? They could have easily faked that too.
Sooner or later you have to rely upon people to tell the
truth and there is no way around that fact. These cameras will make no difference whatsoever.
EXIF, distortions (Score:5, Informative)
The camera stores information about focus distance, focal length (zoom) and exposure parameters as well as other data in each image (in EXIF format, commonly). Example:
Also, you'd also have to account for the distortion effects that are measurable and reproducible with each camera model. For example, barrel or pincushion distortions compound if you take a shot of an existing picture.
Re:2D autocorrelation... (Score:4, Informative)
Since you said "uniform noiseless areas (sky)" - funny thing is, the sky is one of the most difficult things to get an "uniform" picture of. All digital cameras I know of produce "sky noise" in various proportions.
A picture of the sky is how you can quickly check how noisy of an image the camera can make (part of it can be internal image processing, of course).
ElGamal (Score:3, Informative)
Re:Canon (Score:2, Informative)
I work for Canon doing tech support for their cameras, oh by the way.