picture signatures
Could someone please tell me why I would possibly want to sign a picture? All it proves is that I had it in my possession -- it says nothing at all about if its been hacked (and indeed, it can be hacked regardless of what one does). A digital signature on a picture is no better than a court oath saying "yes, I took this picture". The only time you might ever want ANYTHING digitally signed is if you have doubts as to its origin or if someone might deny having signed it. It doesn't do you any good vis a vis verifying origin of a thing. .pm
-----BEGIN PGP SIGNED MESSAGE-----
Could someone please tell me why I would possibly want to sign a picture? All it proves is that I had it in my possession -- it says nothing at all about if its been hacked (and indeed, it can be hacked regardless of what one does). A digital signature on a picture is no better than a court oath saying "yes, I took this picture". The only time you might ever want ANYTHING digitally signed is if you have doubts as to its origin or if someone might deny having signed it. It doesn't do you any good vis a vis verifying origin of a thing.
.pm
Why does anyone ever sign anything? Why did I sign this? The signature attaches the reputation associated w/ a particular key to this particular block of data. I can be certain that you will either get exactly what I wrote, or no if what you recieved isn't. You know this already. The point is, attaching a signature to a picture guarentees that a picture I create hasn't been modified w/o people knowing that its changed since it left my hands. My pictures could have reputations attached to them without the use of digital signatures. This reputation could be used against me if a picture is modified, and my name is still attached to it, but with no verifiable digital signature similarly attached. - -john -----BEGIN PGP SIGNATURE----- Version: 2.3 iQBVAgUBLQ5S8KNqtARNqVmxAQEJuAIAlgpPdPRM+2suslbkF63Nyg14lfBSsT4H hNTGbLLkRVvf/PToW2zmRtufo2WnRvqdkVDrE/WUxhPtvl/3MVIumQ== =+S/A -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ John Blair <jdblair@nextsrv.cas.muohio.edu> phone: (513) 529-4879 Insert cool signature file that makes a trendy, yet bold and original statement about my cyberspace proficiency, then mentions that I'll send you my PGP public key if you want it, and you trust that I'm actually me.
As I noted in my original message, signatures on pictures are not intended to prevent doctoring, but to show where the doctoring was done. A signature is indeed like an affidavat; it associates the reputation of the signatory party with the picture and provides a back-trace of the flow of the bits and sites of possible malfeasance. The idea is that if I have a picture I think is good and true and honest I want to be able to sign it in such a way that if it appears later in doctored form I can prove that those picture bits are NOT mine. If someone wants to make an honest change to a photo (like cropping to fit on a printed page), he has to sign that change. It's protection for photographers, essentially, and for editors. This way when someone complains "Hey! Cropping me out of that picture totally changes its meaning!" I can show that the complainer was in fact in the picture I took. --Alan Wexelblat, Reality Hacker, Author, and Cyberspace Bard Media Lab - Advanced Human Interface Group wex@media.mit.edu Voice: 617-258-9168 Page: 617-945-1842 an53607@anon.penet.fi The belief that enhanced understanding will necessarily stir a nation to action is one of mankind's oldest illusions.
participants (3)
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Alan (Miburi-san) Wexelblat -
jdblair＠nextsrv.cas.muohio.EDU -
Perry E. Metzger