I'm really interested in range proofs, and bulletproof seems to be the most effective range proof.
I saw an example of usage of bulletproofs range proof: You can generate a proof that your age is greater than 18 without revealing your exact age.
That sounds cool, but what I don't understand is how I can prove that my age is verified. Say I'm 12, but while I generate a proof, I pretend that I'm 20 and generate a proof for 20 years. Clearly, I need a third trusted party to verify that my age is really greater than 18. How it can be done?
Maybe I should generate a proof, and then a trusted third party - for example my government - signs that it to make it a valid proof? Is there a better approach?