Public-Key Cryptography

Statements tagged with the public-key area. This is a generated view, not a home directory – a statement can belong to several areas at once. See all statements for the full index, or the schema for what each column means.

Status	Statement	Tags
	Four-party NIKE, quadratic, Maurer’s model Open. Achieved in Shoup’s generic group model by the source paper (Construction 9, Theorem 10); in Maurer’s model the paper’s own O(n^2) attack sets a ceiling that a construction would meet exactly, and nothing is known about reaching it. 5 open	ggmseparationresearch-opennew-idea (ai)
	Quadratic attack on 3-NIKE, Shoup’s model Open in Shoup’s model. Settled by the source paper in Maurer’s model for every K at least 3, including imperfect correctness; its own three-party Shoup construction achieves only an n^1.5 gap, so the truth for three parties lies somewhere between n^1.5 and n^2. 5 open	ggmlower-boundresearch-opennew-idea (ai)
	RBE needs Ω(log n) updates Open. The number of updates for fixed-update-time schemes with polylogarithmic public parameters is known to lie between Omega(log n / log log n) and O(log n); this statement picks the upper endpoint, and the paper’s own tool is proved tight, so it cannot decide the question. 5 open	standardlower-boundresearch-opennew-idea (ai)
	No key agreement from GC-OWF Open for round complexity growing with the security parameter. Proved in full for two messages, which is public-key encryption; the constant-round extension is sketched in the paper’s appendix without a theorem, its security half deferred to the PKE proof. 5 open	otherseparationresearch-openadaptation (ai)
	OWFs are black-box useless for key agreement Open in the general case, which the paper names as the central open problem left by its work. Settled for three restricted protocol classes: constant-query perfect, constant-round constant-query imperfect, and Merkle-type. 6 open	otherimpossibilityresearch-opennew-idea (ai)
	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	standardequivalenceresearch-opennew-idea (ai)
	No round-optimal pairing-free blind signature Open for a polynomial query budget. The impossibility is proved when User_2 and Verify together make O(log lambda) random-oracle queries, including when oracle outputs contain group elements; the superpolynomial message space hypothesis is retained. 5 open	ggmimpossibilityresearch-openadaptation (ai)
	Three moves from DL, ROM only Open: three moves, black-box in the group, ROM only, from DL alone. Three moves is achieved from DDH in the ROM and from DL in AGM+ROM; four moves is achieved from DL in the ROM. 5 open	romassumptionresearch-opennew-idea (ai)
	RBE update bound, key-dependent schedules Open exactly when the update schedule may depend on the sampled public keys, which is the standard on-demand completeness notion. Proved when the schedule is any fixed function of registration times (Theorem 4.1) or of the registered identity names and the CRS (Theorem 4.12). 5 open	standardlower-boundresearch-openadaptation (ai)