How to use the common reference string in groth16 to generate random numbers?

[2pir2]

I am trying to generate a sequence of random number as inputs. I am wondering if I can just use the common reference string in groth16 as the source of random seed.

[ivokub]

There is the api.Commit method which uses the SRS indirectly. It returns a single element (as internally we compute the Pedersen vector commitment which is a big MSM), but you can expand it to a sequence of random values using consecutive multiplications for example.

[ivokub]

We use it in gnark quite extensively actually, it allows to perform efficient random evaluations. But the verifier work becomes less efficient the more times api.Commit is called. For that we have implemented a multicommit method which expands the single api.Commit output to a series and provides them internally to callbacks. See https://pkg.go.dev/github.com/consensys/gnark@v0.11.0/std/multicommit and the example within.