I came across a company that relies on hashing, similar to block chain technology. They explicitly stated in their white paper that hash based cryptographic schemes are inherently post-quantum schemes.
Counter to this, is an article co-authored by Schneier (linked in blog post) that lends support to the idea of Grover's algorithm enabling cryptanalysis of "Keyless Signature Infrastructure" (KSI). Is the position that KSI is inherently a PQC scheme tenable simply because no conventional device is known to have broken it?
It seems like this argument is sleight of hand, given it does not rely on a security reduction of an NP-Hard problem which as I understand is essential to any PQC scheme. Is their use of a modified blockchain method actually post-quantum secure?