Function compute_proof 

pub fn compute_proof(
    password: &str,
    salt_hex: &str,
    params: KdfParams,
    nonce: &[u8],
    op: &[u8],
) -> Result<Vec<u8>, AdminError>

Client side: derive the verifier from password + salt_hex (the daemon’s challenge) and compute the proof for op under nonce. The password is used only locally; only the resulting proof is sent.