multiple std::ecdsa_secp256k1::verify_signature in circuit fail

[70nyIT]

I've a scenario where a series of keys are passed to the circuit (up to 20 ideally) and a loop verifies them all with std::ecdsa_secp256k1::verify_signature

I've noticed that if I have nore than 2 std::ecdsa_secp256k1::verify_signature, the circuit compiles, but when it comes to bb prove it fails.

So let's say I have a simplified version of my circuit as

global MAX_KEYS: u32 = 20;

struct AuthorizedKey {
    x: [u8; 32],
    y: [u8; 32],
}


fn main(
    // Public
    hashed_msg: pub [u8; 32],

    // Private (witness)
    keys: [AuthorizedKey; MAX_KEYS],
    sigs: [[u8; 64]; MAX_KEYS],
) {
    for i in 0..MAX_KEYS {
        assert(std::ecdsa_secp256k1::verify_signature(keys[i].x, keys[i].y, sigs[i], hashed_msg));
    }
}

up to MAX_KEYS compiles. Probably in this simplified version also up to MAX_KEYS = 3. But for sure at MAX_KEYS = 20 it doesn't.

OR to say it better, I can run nargo compile and nargo execute - but when it comes to bb prove -b ./target/my_circuit.json -w ./target/my_circuit.gz -o ./target --oracle_hash keccak --output_format bytes_and_fields I get the following error

Scheme is: ultra_honk, num threads: 16 (mem: 7.03 MiB)
(Experimental) WARNING: Builder failure when we have real witnesses! (mem: 68.48 MiB)
(Experimental) WARNING: Builder failure when we have real witnesses! (mem: 68.48 MiB)
(Experimental) WARNING: Builder failure when we have real witnesses! (mem: 68.48 MiB)
(Experimental) WARNING: Builder failure when we have real witnesses! (mem: 68.48 MiB)
Assertion failed: (remainder_1024.lo == uint512_t(0)) (mem: 76.47 MiB)
Aborted (core dumped)

Any advice on how to handle this case?

[TomAFrench]

Hey @70nyIT, thanks for reporting this. Can you open an issue on https://github.com/AztecProtocol/aztec-packages/issues as issues related to proving with bb need to be reported there.

It would be great to have a full set of inputs which you see the error as well to ensure that we're all trying to generate the same proof.