[withinboredom]

Why do you need the cryptographic signature? Who needs to know that I was the original owner of a tea kettle 7 years ago that has been sold in a yard sale twice?

Absolutely nobody.

Having an actual UPC (which coincidentally stands for "Universal Product Code") that is globally unique would be extremely useful. Further if all the parts were listed in the UPC (so it could be easily sold for parts, or even if I was looking for part abc123, I could find what products it is in), would be far more useful than caring who owns it.

[EricRiese]

It's the merchant's signature. The buyer's info isn't part of the receipt as I envision it. It's necessary for some of the functionality I mentioned but not all.

Also you're assuming the receipt from one transaction follows the item. That's not necessary. Every transaction gets a new receipt. But you would want a history of receipts for a Rolex or car.

Picture this, I submit the item to Craigslist with my receipt. It's not posted, but Craigslist verifies it and puts a check mark on the post.

[withinboredom]

That doesn’t prove anything. It just means you had access to a receipt at some point. This is a human problem that can’t really be solved with technology.