MD5

The media has once again created controversy by overstating a court
decision. (this one:
http://www.news.com.au/story/0,10117,16204811-1242,00.html) The court case
was lost not due to the use of MD5, it was lost due to RTA's inability to
"find an expert" to prove the pictures were not tampered with after they had
been taken. This means one or more of the following conditions occurred:

- they actually couldn't find anyone (although it's unlikely)

- they couldn't find anyone that could explain MD5 in simple terms that
would indicate that the liklihood that the traffic infraction actually
occurred. Hint: think DNA evidence. You will always hear "probabilities"
discussed when lawyers discuss DNA. Yes, there are collisions in MD5 number
space. The probability of forgery goes down very fast if that "collision"
has the same MD5 hash, looks like a picture, of the intersection in
question, with the defendant's car passing through it, with the defendant's
license plate in view, with the camera's timestamp (and other) data embedded
in the picture.

- the prosecution was unable to display the chain of evidence, in the form
of being unable to prove when the MD5 hash was generated. The hash being
embedded in the picture may actually cause a problem because it means that
the picture was changed after it was taken, by the camera itself. However,
this is a procedural problem, not a technical one, and would translate into
the prosecution not being able to find anyone willing to take an oath to
assert/support the accuracy of the data.

I doubt that MD5 hashing of traffic pictures will cease. Rather, I believe
that how they're presented in court will change.