Enable using transcripts other than merlin::Transcript.

[JayWhite2357]

Background and Motivation

Currently, the Proof of SQL prover uses the merlin crate to provide it's public-coin transcript, created here:

sxt-proof-of-sql/crates/proof-of-sql/src/sql/proof/query_proof.rs

Line 62 in 29d334d

let mut transcript: Transcript =

.
However, merlin does not support no_std (see #117 and zkcrypto/merlin#8) and is not conducive to use within the EVM/Solidity.

#123 and #159 add a new Transcript trait that allows for using different transcripts. (Such as the simple Keccak256Transcript.)

If we replace all uses of merlin::Transcript with impl Transcript, we enable the ability to use any transcript implementation that is desired.

Requested Changes

We need to replace all usage of merlin::Transcript with impl Transcript. Tests can still leverage merlin::Transcript because they need a concrete implementation, but all other code should be written generically.

• extend_serialize_as_le can replace append_auto

• extend_canonical_serialize_as_le can replace append_canonical_serialize

• scalar_challenge_as_be can replace challenge_scalar_single ( and challenge_scalars )

• other methods can be better replacements as relevant

• CommitmentEvaluationProof::new, CommitmentEvaluationProof::verify_proof, CommitmentEvaluationProof::verify_batched_proof should accept impl crate::base::proof::Transcript instead of merlin::Transcript.

• All implementers of CommitmentEvaluationProof will need to be updated to implement the changes properly.

  • InnerProductProof - this will still internally need to use merlin::Transcript. This is handled via wrap_transcript.
  • DoryEvaluationProof - the usages of the transcript bubble down to DoryMessages.

• Either QueryProof::new and QueryProof::verify can be made generic w.r.t. Transcript, or QueryProof itself can be made generic w.r.t. Transcript. It is unclear which is a better design choice. Both solutions will require replacing the old transcript usage with the new within those functions.

• Tests will likely need to be refactored, but should just used merlin::Transcript as the concrete type. In the future, we may wish to migrate tests to use Keccak256Transcript instead. This can be a separate issue.

[JayWhite2357]

@jvff Here is the issue that we discussed. This should complete the work to support wasm32-unknown-unknown without JS.