Quadrox Video Authentication - Manual (Page 12)

Video Authentication Manual 12
Version 4.4 Series
3.5 Checking Signature
Once the certificate is trusted, the signature message can be decoded. Because the certificate
is trusted, we know that a) the information in the signature is correct (wasn’t changed) and b)
the signature was produced on the recorder from which the movie is claimed to have
originated. If the signature was forged, the certificate will not decode it.
Inside the signature, a hash value links the certificate uniquely to the movie file. By
recalculating the hash in the courtroom, we can be sure that a) this signature belongs to this
particular movie and b) the movie hasn’t changed since the signature was created. If the
movie was forged, the hash value would be different and the signature invalid.
These actions are performed automatically by the Digital Signature Verifier tool.
Digital Signature Verifier main screen
Open the Digital Signature Verifier tool.
Enter the locations of the movie and signature files and click the Verify button.
If the signature can be decoded and the hash information matches the movie, the
movie authenticity is proven and the following information screen will be shown. The
displayed information is part of the digital signature and is likewise proven to be
authentic.
Trusted signature information screen