Keccak256 preimage proof cannot be verified

[ax0]

Aim

Generate and verify a proof for the program

use dep::std::hash::keccak256;

fn main(x: [u8; 3], len: Field) -> pub [u8; 32] {
    let len_u32 = len as u32;
    keccak256(x, len_u32)
}

with Prover.toml given by

x = [1,2,3]
len = 2

Expected Behavior

A proof may be generated and verified.

Bug

A proof may be generated but verification fails.

To Reproduce

1. Create a new Nargo project and populate main.nr and Prover.toml with the above snippets.
2. Run nargo prove p.
3. Run nargo verify p.

Installation Method

Compiled from source

Nargo Version

nargo 0.8.0 (git version hash: 1056ba1, is dirty: false)

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

No response

[kevaundray]

Is this ran with the experimental-ssa or the old ssa? cc @guipublic for visibility

[ax0]

Just checked and passing --experimental-ssa yields the same result, so both.

[kevaundray]

@guipublic are there any blockers on diagnosing this issue?

[guipublic]

@guipublic are there any blockers on diagnosing this issue?

no, had to work around barretenberg but now I have a repro there and I am experimenting a fix.

[kevaundray]

Update on this: @guipublic will create a unit test that is failing on the barretenberg side

[guipublic]

Fixed by AztecProtocol/barretenberg#632

[guipublic]

The fix has now been integrated into noir with the last backend update. I am closing the issue.