I've been experimenting with USTP-Secure, a reliable UDP transport I've been building.
The latest version adds:
Optional congestion control
Retry tokens to reduce amplification risk
Optional cleartext + HMAC mode (integrity without encryption)
Authenticated ACK/NACK packets
One design choice I'm still thinking about is congestion control for an intentionally unordered reliable transport.
Unlike TCP, USTPS doesn't enforce ordered delivery at the transport layer. Missing packets can be retransmitted selectively while newer packets continue flowing.
I'm curious how others would approach congestion control for this kind of transport, and whether there are existing designs I should study beyond QUIC, RTP/SRT, and similar protocols.
Project: https://github.com/x1colegal/USTP-Secure