  We consider the problem of post-quantum secure and ultra-reliable
communication through a heterogeneous network consisting of multiple
connections. Three performance metrics are considered: security, throughput,
and in-order delivery delay. In this setting, previous work has looked,
individually, at the trade-offs between in-order delivery delay and throughput,
and between security and throughput. This is the first work considering the
trade-off between all three for heterogeneous communication networks, while
taking the computational complexity into account. We present LL-HUNCC, a low
latency hybrid universal network coding cryptosystem. LL-HUNCC is an efficient
coding scheme which allows for secure communications over a noisy untrusted
heterogeneous network by encrypting only a small part of the information being
sent. This scheme provides post-quantum security with high throughput and low
in-order delivery delay guarantees. We evaluate LL-HUNCC via simulations on a
setting inspired by a practical scenario for heterogeneous communications
involving a satellite communication link and a 5G communication network. Under
this scenario, we compare LL-HUNCC to the state-of-the-art where all
communication paths are encrypted via a post-quantum public-key cryptosystem.
