pub unsafe extern "C" fn secp256k1_whitelist_sign( ctx: *const Context, sig: *mut WhitelistSignature, online_keys: *const PublicKey, offline_keys: *const PublicKey, n_keys: size_t, sub_pubkey: *const PublicKey, online_seckey: *const c_uchar, summed_seckey: *const c_uchar, index: size_t) -> c_int