Generic Group Model (GGM)

Status Statement Tags
dv-SNARG, One Group Element
Numbered Conjecture 1.3 of the source. Its own theorems achieve one group element plus O(tau) bits, and (with a random oracle) one group element, one hash output and about 2 tau bits; the conjecture halves the additive term to tau + o(tau) and asks for no random oracle. 4 open
Generic Group ModelProof Size Lower BoundsSnarksggmcharacterization
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
Generic Group ModelNon Interactive Key Exchangeggmseparation
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
Generic Group ModelNon Interactive Key Exchangeggmlower-bound
r-round DLOG tradeoff
Open for every intermediate r: the r = 1 endpoint is the source’s own theorem and r = T is Corrigan-Gibbs–Kogan, with nothing proved in between. The source conjectures the interpolating formula and says a matching attack exists at every r, so the missing half is the lower bound. 6 open
AdaptivityDiscrete LogarithmGeneric Group ModelTime Space Tradeoffsggmtight-bound
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
Black Box SeparationsBlind SignaturesGeneric Group ModelSignature Schemesggmimpossibilityadaptation (ai)
Non-adaptive DDH bound
Open, and asserted rather than asked: the source proves 1/2 + O~(T^2/N + sqrt(ST/N)), states twice that it conjectures this is not tight for DDH, and names 1/2 + O~(T^2/N + ST/N) as the right answer. The same theorem’s square-DDH bound is sharp, with a matching attack, which is what makes the DDH case a question rather than a suspicion. 6 open
AdaptivityDiscrete LogarithmGeneric Group ModelTime Space Tradeoffsggmtight-boundadaptation (ai)
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