Quantum Cryptography

General security notions, constructions, and separations involving quantum adversaries or quantum information.

Status	Problem	Tags
	CPA PKE, Quantumly Broken The first item in the source’s Open Problems section. It builds counterexamples for PRFs, CPA-secure symmetric-key encryption, MACs, signatures and CCA-2-secure public-key encryption, all classically secure under LWE via black-box reductions and all quantumly broken with two or three classical queries. CPA-secure public-key encryption is the case its technique cannot reach, and it says why. 4 open	Black Box Separations Learning With Errors Quantum Cryptographyseparation
	One Haar State Looks Like Many Stated in the source’s Open Problems section as a conjecture it believes true, with the note that it could neither prove it nor find it proved or even formalised anywhere. The source proves a strictly weaker pointwise domination bound, its Lemma 2, sufficient for its own applications and silent about total variation distance. 5 open	Pseudorandom Quantum States Quantum Cryptography Quantum Informationothertight-boundadaptation (ai)
	Erasing real-or-random vs Boneh–Zhandry Open: whether erasing real-or-random security implies Boneh-Zhandry security. The reverse non-implication is proved only in the quantum random oracle model, and this direction is one of six non-implications the source paper conjectures and does not prove. 5 open	Quantum Cryptography Quantum Encryption Notionsseparation
	One erasing challenge vs many embedding learns Open: whether a single erasing two-ciphertext challenge query, with classical learning queries, implies security against polynomially many embedding-model superposition learning queries. One of six non-implications the source paper conjectures, and on its own account the one that would close the most remaining cells. 5 open	Quantum Cryptography Quantum Encryption Notionsseparation
	Standard real-or-random vs embedding two-ciphertext Open: whether one standard-oracle real-or-random challenge query implies one embedding-model two-ciphertext challenge query, with classical learning queries on both sides. Both notions are singleton classes in the source’s classification, and this is one of six non-implications it conjectures. 5 open	Quantum Cryptography Quantum Encryption Notionsseparation
	OWF minimality, non-black-box reductions Open when the classical security implication is not witnessed by a black-box reduction between the two games. Settled affirmatively whenever it is, for uniform and non-uniform quantum adversaries alike, with the implementation reduction left arbitrary. 5 open	Black Box Separations One Way Functions Quantum Cryptographyequivalence