Quantum Cryptography in Algorithmica

We construct a classical oracle relative to which P = NP yet single-copy secure pseudorandom quantum states exist. In the language of Impagliazzo’s five worlds, this is a construction of pseudorandom states in ”Algorithmica,” and hence shows that in a black-box setting, quantum cryptography based on pseudorandom states is possible even if one-way functions do not exist. As a consequence, we demonstrate that there exists a property of a cryptographic hash function that simultaneously (1) suffices to construct pseudorandom states, (2) holds for a random oracle, and (3) is independent of P vs. NP in the black-box setting. We also introduce a conjecture that would generalize our results to multi-copy secure pseudorandom states.