Post-Quantum Interactive Hashing Theorem. The post-quantum theme continues in this post as well! 😁 Imagine a protocol that maintains its security properties even against a quantum adversary. Consider the concept of a *cryptographic commitment scheme*: it involves two key aspects: first, no one should learn your secret message until you choose to reveal it; second, once the commitment is made, you should not be able to change your choice. Now, let’s expand this to include multiple possible secrets rather than just a single option. In this scenario, one party holds a specific string, while the other party poses a series of random "questions" (or hashing challenges). If you are a classical computer, everything works as intended. However, if you are a quantum computer, problems arise—not for you, but for everyone else whom you might target🙃 As an adversary with a quantum computer, you can leverage qubits in a state of superposition to employ more sophisticated strategies. Consequently, after the protocol concludes, you might be able to produce two distinct, valid "openings" (reveals) instead of just one. (In this context, two openings refer to two different answers that an adversary attempts to pass off as a single, valid outcome of the protocol.) In the paper, the authors prove that, under certain cryptographic assumptions, a quantum adversary cannot successfully execute an attack to find two distinct, valid openings. https://t.co/MTNUsBGpu7