Where do you go to authenticate Canon photos?

I'm looking for an accredited service that can authenticate a set of photos from a Canon Powershot S95 camera (each saved simultaneously to jpg and raw) and put them in the order they were taken.

The file names among the photos include numbers that are near each other, but what if they can't be relied on?  What if something was done to change that numbering?  There's a similar concern for date and time, these could have been changed between photos, too.

Is there some information stored with each photo (each pair of photos, jpg and raw) that can indicate where in a sequence the photo was taken? Something a user couldn't alter in the camera?  What's important is the sequence in which the photos were taken.

Going beyond the technology, do you know of a service (in the US) that has good accreditations and can also determine the sequence the photos were taken.  The accreditations are to help convince a disbeliever.  This is the same question as above, except instead of it being DIY it's deferring to a professional organization.

Thanks!

(I originally put a similar post on a Canon forum but it doesn't seem to fit with the other discussions.)

File names& basic EXIF info are all easily alterable. If you can extract the shutter activation information it should be possible to use this to confirm the shooting order. This is less likely to have been altered, and is often less obvious in the exif.

Not all cameras store this information in the EXIF several of mine have convoluted button presses to display the information, but others have it hidden in EXIF - there are websites that provide the shutter count if you upload an image. (Works for my DSLRs but not my micro four thirds bodies)

AFAIK general EXIF tools don't display the shutter count.

Mel in LA wrote:

I'm looking for an accredited service that can authenticate a set of photos from a Canon Powershot S95 camera (each saved simultaneously to jpg and raw) and put them in the order they were taken.

The file names among the photos include numbers that are near each other, but what if they can't be relied on? What if something was done to change that numbering? There's a similar concern for date and time, these could have been changed between photos, too.

Is there some information stored with each photo (each pair of photos, jpg and raw) that can indicate where in a sequence the photo was taken?

Lots. ExifTool is free and gives you access to just about everything in the image file, including timestamps, shutter count (if the camera records it), exposure parameters, where the camera saw faces, etc. Some of the more obscure fields should have time-sequence correlations; for example, battery power and camera temperature readings should progress over time within a sequence of consecutive exposures. Then again, I'm talking about statistical correlation, not legal proof.

Something a user couldn't alter in the camera? What's important is the sequence in which the photos were taken.

How sophisticated is the user? Pretty much everything can be edited (e.g., using ExifTool), but not in camera (unless you reprogram the camera using CHDK), and it would take significant knowledge to edit everything in self-consistent ways. My understanding is that Canon raw image data is encoded in a way that allows forensic checks that that data has not been altered, but I don't know any details of that, nor do I know of anything that confirms that images haven't been edited.

Going beyond the technology, do you know of a service (in the US) that has good accreditations and can also determine the sequence the photos were taken. The accreditations are to help convince a disbeliever. This is the same question as above, except instead of it being DIY it's deferring to a professional organization.

http://fourandsix.com/ used to be the place I'd go first for such stuff. Apparently, their izitru is now available via https://www.darpa.mil/program/media-forensics . That said, I don't recall them dealing with image sequencing per se....

petrochemist wrote:

File names& basic EXIF info are all easily alterable. If you can extract the shutter activation information it should be possible to use this to confirm the shooting order. This is less likely to have been altered, and is often less obvious in the exif.

Not all cameras store this information in the EXIF several of mine have convoluted button presses to display the information, but others have it hidden in EXIF - there are websites that provide the shutter count if you upload an image. (Works for my DSLRs but not my micro four thirds bodies)

AFAIK general EXIF tools don't display the shutter count.

I sort of recall seeing that certain Nikons had a feature that used digital signatures to verify that an image was "unaltered" compared to what the camera took.

I don't recall which models it was available for (definitely only for upper-end professional units), or if it was even a "standard" feature as opposed to something only sold to law enforcement organizations.

(Googling returned https://imaging.nikon.com/lineup/software/img_auth/spec.htm - which makes it seem to me like this feature is now discontinued in newer cameras?)

I am, however, about 99% certain there are no viable technical solutions for anything in the PowerShot line for ensuring that images weren't altered after capture.