A Note on "New techniques for noninteractive zero-knowledge"
This is an incremental correction that impacts cryptography researchers by invalidating prior claimed solutions to fundamental NIZK problems.
The authors identified a flaw in a 2012 paper by Groth et al., which claimed to solve long-standing open problems in noninteractive zero-knowledge (NIZK) arguments, showing that the prover can cheat the verifier, leaving these problems unresolved.
In 2012, Groth, et al. [J. ACM, 59 (3), 1-35, 2012] developed some new techniques for noninteractive zero-knowledge (NIZK) and presented: the first perfect NIZK argument system for all NP; the first universally composable NIZK argument for all NP in the presence of an adaptive adversary; the first noninteractive zap for all NP, which is based on a standard cryptographic security assumption. These solved several long-standing open questions. In this note, we remark that their basic system is flawed because the prover can cheat the verifier to accept a false claim. Thus, these problems remain open now.