Common serialization format between shared between all zk-snarks framworks

[tdelabro]

Here is my issue:
I want to generate a groth16 circuit using Arkworks. Let's say I also want to run it using Arkworks. I will get the VerifyingKey, the Proof, and an array of E::ScalarField where E: Pairing as my public inputs.

Now I want to verify this on another service that runs in another language, let's say in the user browser using snark.js.
I have to serialize all the previously mentioned data structures in a format that is understandable by Snark.js.
Currently, the framework offers a CanonicalSerialize trait, which is optimized but not compatible with other frameworks. Neither snark.js or gnark implement deserialization this way.

So I had to cook my own serialization library, which is not easy because all of the actual types for the numbers we are using are abstracted behind traits. I found that I could convert those to BigUint and then serialize them as HexString.
Now I have to build the same thing in reverse for all the other libs. But I'm not even able to do it for arkworks (probably not without unsafe) because I cannot initialize those structs with custom arbitrary values (the methods to do so are not exposed). Only CanonicalSerialize allows you to do this.

My request would be for a human-readable serialization to be implemented everywhere Canonical(De)Serialize is. And, ideally, for this format to be shared between all the major zk snarks frameworks out there.

Is this something you already thought about? Did I miss a way to do it easily? How can I help to push this forward?

[ivokub]

From Consensys/gnark#1206:

Yeah, it is inconvenient that every circuit has their own serialization format. We have looked into using some general IR, but it has seemed to be difficult to have a generic implementation due to particular optimizations etc. what every frontend does.

There was an effort Vamp-IR, but it seems that its development has stopped.

[readygo67]

From Consensys/gnark#1206.
I think the BigUint may be the best base for all types in different snark libs.