Function sign_live_response_with_window 

pub fn sign_live_response_with_window<S, Sig>(
    cert_id_der: &[u8],
    status: LiveCertStatus,
    nonce_bytes: &[u8],
    responder_key_bytes: &[u8],
    signer: &mut S,
    now: u64,
    source_this_update: u64,
    source_next_update: u64,
    responder_cert_der: Option<&[u8]>,
) -> Result<Vec<u8>>
where
    S: Signer<Sig> + DynSignatureAlgorithmIdentifier,
    Sig: SignatureBitStringEncoding,

Sign only within the authenticated source window; producedAt is signing time, thisUpdate remains the time the source actually established the status.