A) fake news is hard to define and agree upon
B) different people will have different criteria definition and Venn diagrams of fake news
C1) many people and organizations start and distribute fake news knowing them to be such
C2) many people and organizations start or propagate fake news while earnestly believing them
Can you help understand how block chain or public key cryptography will help or address anything relating to fake news? Is there an underlying assumption that ascertaining identity will help? Because from my perspective majority of fake news are created and propagated by readily and eagerly identifiable people, whether potus or my cousin on Facebook and anything in between.
In other words, today already I pretty much know who is relating any given piece of news. I may even know where or who originated them. It does not in the least solve the problem that my liberal and conservative, atheist and religious. Rich and poor, immigrant and local, technical and humanities etc neighbours have completely different parameters and selection of trust. Identifying the source helps not a bit with radically different selections of source. And then we get to "disagreeable" topics - how will block chain help those who fundamentally disagree on climate abortion religion economy foreign politics military basic income refugees healthcare rights etc. They will continue to pick and choose whatever our inherent bias is. There is this utopian notion that tech framework will solve a human problem.
In my experience, the reason fake news is actually a problem is because supposedly-reputable people and organizations are themselves spreading partially or completely false information. So the information they spread would have a perfectly valid, legitimate signature—and still be just as false.
Blockchain cannot solve the problem of people lying. It cannot differentiate between what is true and what is false in the real world.
That does not seem to be the problem (and insofar as it is, HTTPS/TLS seems pretty good at fixing it: if you go to https://www.nytimes.com, you can be pretty sure that you get the NYT). I don't see what blockchain could add here?
I don't think blockchains are the only or even best solutions to fake news, but the ecosystem build around them uses public-key cryptography for everything.
A world where every piece of information is signed, could be a harsh blow for fake news. It's what PGP always wanted to go mainstream. Maybe, the money behind it (reasonable or not) is finally enough to motivate the mainstream.