17 Dec
2003
17 Dec
'03
11:17 p.m.
Peter Wayner:
I think signing photographs and movie images is a difficult problem. Why? Because one flipped bit will completely screw up the hash function.
Is a one-way hash function or digital signature possible with the following property: signature verification doesn't just determine the boolean altered vs. pristine, but also shows the picture distance between the altered and original? Forgery may often require an editing distance much greater than the error rate from media noise or lossy compression. Nick Szabo szabo@netcom.com