IND CCA Secure Key Encapsulation Mechanism in the Quantum Random Oracle Model, Revisited
With the gradual progress of NIST's post quantum cryptography standardization, the Round 1 KEM proposals have been posted for public to discuss and evaluate. Among the IND CCA secure KEM constructions, mostly, an IND CPA secure (or OW CPA secure) public key encryption (PKE) scheme is first introduced, then some generic transformations are applied to it. All these generic transformations are constructed in the random oracle model (ROM) To fully assess the post quantum security, security analysis in the quantum random oracle model (QROM) is preferred. However, current works either lacked a QROM security proof or just followed Targhi and Unruh's proof technique (TCC B 2016) and modified the original transformations by adding an additional hash to the ciphertext to achieve the QROM security.
CRYPTO