I'm student studying about bitcoin and blockchain. I want to know why all blocks have signature and key pair after the transaction is over.
Why I ask this, I'm studying post quantum cryptography (PQC) and almost PQC have very large key and signature size, but now bitcoin block size is limit to 1MB. So if the hardware performance will be similar to nowadays in future, then I think the block size is critical.
I read the bitcoin post quantum white paper, but there solution is that increase the block size to 16MB.
Is there any reason to store the key and signature? Is there something critical vulnerability?