Trusted entities could vouch for the veracity (or other aspects) of things, especially if they are close to the source.
We already implicitly do this: if a news outlet we trust publishes a photo and does not state that they are unsure of its veracity we assume that it is an authentic photo. Using cryptographic signing that news outlet could explicitly state that they have determined the photo to be real. They could add any type of signed statement to any bit of information, really. Even signing something as being fake could be done, with the resulting signed information being shareable (although one would imagine that any unsigned information would be extremely suspect anyway).
The web of trust approach is to have a distributed system of trust that allows for less institutional parties to be able to earn trust and provide 'trusted' information, but there are also plenty downsides to it. A similar distributed system that determines trustworthiness in a more robust way would be preferable, but I am not aware of one.
We already implicitly do this: if a news outlet we trust publishes a photo and does not state that they are unsure of its veracity we assume that it is an authentic photo. Using cryptographic signing that news outlet could explicitly state that they have determined the photo to be real. They could add any type of signed statement to any bit of information, really. Even signing something as being fake could be done, with the resulting signed information being shareable (although one would imagine that any unsigned information would be extremely suspect anyway).
The web of trust approach is to have a distributed system of trust that allows for less institutional parties to be able to earn trust and provide 'trusted' information, but there are also plenty downsides to it. A similar distributed system that determines trustworthiness in a more robust way would be preferable, but I am not aware of one.