# Questions tagged [fiat-shamir]

The Fiat–Shamir heuristic takes an interactive proof of knowledge and uses this as base to create a digital signature.

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### Weak Challenge Generation - Fiat-Shamir Heuristic

The Fiat-Shamir heuristic may be applied to transform a Sigma-Protocol on R(x,w) into a ZKPoK. Let's call the prover's first message ...
72 views

### Why Fiat-Shamir based signatures incur a security loss?

I read here that assuming we have a Fiat-Shamir (FS) signature $\Sigma$ that is secure based on the hardness of a particular hard problem $\Pi$. Then, the security proof of $\Sigma$ in the classical ...
106 views

### Could be El-Gamal signature scheme constructed via Fiat-Shamir heuristic?

For example, Schnorr signature is pretty similar to El-Gamal. And everywhere where Schnorr signature is explained (for example - on Wikipedia), there's said that there's Schnorr scheme which is ...
54 views

### Is using Fiat-shamir Heuristic safe?

What I'd like to do is to have the Prover store a value x where x remains hidden. From x, I'...
71 views

### Sigma Protocol with Privacy-preserving Discrete Logarithms?

I've been reading up on Sigma Protocols and Fiat-Shamir Heuristic. There is a small problem I see here that is possibly already solved, but I'd like to know if it has a solution. Peggy wants to prove ...
306 views

### Need tips on how to break Fiat-Shamir sigma-protocol (programming challenge)

I'm completely stuck on an university programming challenge and I need some tips to get me out of the valley I'm in, you don't need to give the full answer if you do not wish to. What we have: Fiat ...
46 views

### Valid reencryption of simple mixnet

How can I provide a non interactive proof using the Fiat Shamir method for the valid reencryption of a simple mixnet?
175 views

### Fiat Shamir with S^3

I'm trying to do Fiat Shamir but with $I = S^3 \pmod n$ where $S$ is the secret key. How will I prove that I know the cube root? I tried doing the old formula but with instead with \$(RS)^3 = x*I \pmod ...