While timestamps do have some use for pictures, they're more limited in what they'll do for you. Paul Baclace suggested that if you have the oldest secure timestamp for a given picture, then you can prove it's yours. Some problems include: - NOT having the timestamp doesn't prove it's NOT yours, whereas a signature is real good evidence. - If somebody changes one or more bits of the picture, your timestamp is no longer valid; the same is of course true with signatures. But with signatures, you can demonstrate *who* you got the picture from, whereas timestamps don't do that very well (though I suppose you could accept signed timestamps as well as acceptingsigned pictures.) - Timestamps are more anonymous, but you can achieve the same effect with signatures by creating a random public-private key pair to signing each picture, and then demonstrate knowledge of the private key if you need to prove ownership. On the other hand, secure timestamps *do* give you timestamping, which signatures by themselves don't, so it's certainly a valuable addition. Bill