Compressed Oracle Duality: A simple framework for knowing what quantum adversaries know

arXiv:2611.00609v1 Announce Type: new Abstract: Given a quantum adversary that queries a random oracle, how do we characterize the information that they "know"? The Compressed Oracle method of Zhandry (CRYPTO 2019) is one method that records the queries that the adversary makes; this recording serves as a representation of the information that is learned. However, a significant limitation of the Compressed Oracle method is that it may continue to store information that the adversary has "forgotten." This issue is especially pertinent in the space-bounded setting, where the adversary may uncompute information to free up space, while the information may still reside in the compressed oracle.