Function calculate_client_hash 

fn calculate_client_hash(
    session_key: &[u8],
    username: &str,
    key_uuid: &str,
    salt: &[u8],
    shared_a: &BoxedUint,
    shared_b: &BoxedUint,
) -> [u8; 32]

The client verification hash sent to v2/auth/confirm-key: H(H(N) xor H(g) || H(I) || s || A || B || K).