Proof of knowledge and replay attacks I was reading the ZK proof of knowledge of Schnorr and fiat shamir transformation, and I figured out that replay attacks are possible. Why these protocols don't take into account this attack? That seems very strange.

Thank you.
In General: ZK protocols become insecure if computed concurrently; I think this is what you are referring to. If the protocol is run in parallel, an adversary could request a proof of two relationships and produce a witness for the first with the knowledge gained from the second prover-output. When run concurrently, this attack cannot be executed because the adversary cannot receive a second commitment on the same relation to learn/produce a witness for the first. As far as I know, there is no protocol that achieves concurrent security.