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Worried about Digital Evidence Tampering?
2marcus writes "As digital technology continues to improve and is used in more and more applications, the ease of tampering with digital files becomes more pertinent. This is especially important in the field of criminal justice, where even the appearance of possible impropriety can sway a jury. CNN has an article on the issues with digital photos being used for fingerprints and other forensics evidence."
So technology has answered, its back in the hands of law enforcement to present their case properly.
Witnesses credibility has been under debate for years. Witnesses can be influenced by suggestive questioning, their own backgrounds and prejudices, or the amount of sleep they have had on a given day. And how do you quantify or qualify that kind of tampering? Witness testimony has been used for millenia. No evidence is foolproof. The problem is 1. to know what kind of tampering can be done and be aware and wary of it and 2. to get the trust of the public in that type of evidence so it can be admitted, falible or not.
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You can prove through cryptographic means, md5 sums, etc, that the odds a digital file has been tampered with are billions-to-one. Some cameras designed for LEOs have such stuff built in, you can prove that the file hasnt changed since the camera took it.
With analog, you end up with a dozen 'experts' with magnifying glasses who cant decide if its bigfoot or a guy in a gorilla outfit.
Besides, cases are built on actual physical evidence. That freak who kidnapped the little girl from the carwash will get the chair because of DNA and other evidence, not the surveillance footage.
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No, law enforcement officers are required to maintain strict control and tracking of evidence now ("Chain of Evidence") to try and prove the evidence has not been tampered with. The mutability of digital records adds extra considerations, in some cases.
One way of hardening the chain is to burn the digital record onto a CD-R, with a least two witnesses and recording the serial number of the CD-R onto the evidence log.
Sure, it's a little easier, but it's not something we suddenly can do that we weren't able to do previously.
You are not alone. This is not normal. None of this is normal.
I was told by a lawyer to get photographic evidence , not in digital, or film but Instant film format.
/developed.
Jury's, and judges consider the instant developed photos of the instamatic camera are considered unalterable because of how they are made
usually the oldest technology is the most accepted in the court of law.
It's not hard for experts to detect Photoshop fakery, even if amateurs can be fooled. If you move objects around in the picture, you'll never be able to get every cast shadow right, or get the lighting of the removed objects right. The analysis process that the experts use is analogous to ray tracing run backwards: given the images, figure out where the lighting is. Then boundaries between regions that have been altered and regions that have not come out clearly.
Furthermore, as its name implies, many of the Photoshop tools correspond to tricks that photographers have traditionally played in darkrooms, it just makes it easier.
at least one case where the FBI insured that an innocent man was convicted of murder and sent to prison in order to protect their own informant.
What case was that?
Joseph Salvati ABC News
A quick google turns up other probable cases.
And it's not going to change until someone gets the guts to start bringing charges against cops and prosecutors who knowingly use false information, or withhold information.
at BrightNoise Inc that works with IP based cameras and video "servers" to stream images and detect motion, alarms, etc in sensitive areas . One of the biggest concerns I have had is tampering with jpegs or avi files exported from these softwares. AFAIK none has been challenged in a court of law here in the states, but we have had several schools and companies use it as proof of guilt for thieving and extortion!! The approach Milestone took was to make it exceedingly difficult to tamper with the original recording but allow exports. I train users to immediatly remove the original drives or enter server when there is an event of serious enough magnitude, lets face it whats a few thousand dollars when your talking about firing someone or worse? Personally I would like to see water marks or some embedded checksum in the images.
Si vis pacem, para bellum! For evil to succeed good men need only do nothing!
It's not hard for experts to detect Photoshop fakery, even if amateurs can be fooled.
I work in wholesale justice -- I do a lot of court-appointed work. There is no way that an expert will be approved in every case to authenticate or detect alterations of digital images. At the basic level of the legal system, the people who most need this sort of protection (accused criminals) will not be able to afford it.
I like the idea of digital photographs with some sort of cryptographic self-authentication. It would reduce the risk of cowboy cops faking evidence and putting it over on juries and judges. Someone needs to police the police, and this might help.
GF.
Lots of petrified grits
NIST has a test spec for drive imaging software for forensic use.
m
http://www.cftt.nist.gov/documents/Atlanta.pdf
They have been testing a bunch of programs, and so far dd on Free BSD has performed best:
http://www.ojp.usdoj.gov/nij/pubs-sum/203095.ht
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