Running on a Trusted Internal Network

This guide covers what you can and cannot turn off when every client and server sits on the same internal subnet. The short answer is that TLS stays on, but the PKI around it does not have to: you can skip certificate validation, or drop certificates entirely and authenticate with a shared secret. Read this when you are deploying inside a VPC, a service mesh, or a lab network and do not want to run a CA.

You cannot disable TLS

There is no option for it, in this library or in QUIC. Packet protection is part of the transport, not a layer stacked on top of it (RFC 9001 §3):

• Every packet is AEAD-sealed and header-protected. Application data travels under 1-RTT keys derived from the TLS 1.3 handshake.
• Transport parameters are carried inside the TLS handshake, so connection setup has no cert-free path.

Initial packets are the one nuance: they are protected with keys derived from the client's Destination Connection ID, which any observer can compute. That protects against off-path injection, not disclosure. Everything after the handshake keys are installed is confidential.

A listener with neither certificates nor a PSK is refused up front:

1> quic:start_server(my_server, 4433, #{alpn => [<<"echo">>]}).
{error,no_auth_method}

Skip certificate validation

Use this when you already have a certificate on the server (a self-signed one is fine) and just do not want to distribute a CA to clients. Clients validate by default, so this is opt-in. verify_none, none and false all mean the same thing.

{ok, Conn} = quic:connect(Host, Port, #{
    verify => verify_none,
    alpn => [<<"echo">>]
}, self()).

The server still needs a cert + key pair:

{ok, _} = quic:start_server(my_server, 4433, #{
    cert => CertDer,
    key => KeyTerm,
    alpn => [<<"echo">>]
}).

Notes:

• Traffic is encrypted exactly as it would be with a validated chain.
• The client does not check who it is talking to. Anyone who can get packets to the client can present any certificate. Only do this where you trust the path.

Drop certificates entirely

Use an external PSK (RFC 8446 §4.2.11) when you control both ends and want no X.509 at all. Both sides share a secret out of band, and both sides are authenticated by it.

Server:

{ok, _} = quic:start_server(my_server, 4433, #{
    alpn => [<<"echo">>],
    psks => #{<<"node-a">> => Secret}
}).

Client:

{ok, Conn} = quic:connect(Host, Port, #{
    verify => verify_none,
    alpn => [<<"echo">>],
    external_psk => {<<"node-a">>, Secret}
}, self()).

Notes:

• The secret is consumed as raw IKM by the TLS key schedule. Give it at least 128 bits of entropy, from crypto:strong_rand_bytes/1 or your KMS.
• The default mode psk_dhe_ke keeps forward secrecy. psk_ke skips the (EC)DHE and drops it.
• verify => verify_none on the client does not weaken this. The client requires the server to select the offered PSK and aborts if it does not, so there is no silent fallback to an unverified cert.
• For per-identity lookup instead of a static map, use psk_callback.

Full guide: PSK.md.

Erlang distribution

The same rules apply. Distribution over QUIC runs the same handshake, so it cannot run in cleartext either, and it accepts the same two ways to shed PKI. A node configured with neither certificates nor a PSK fails to start its listener with {error, {credentials, no_credentials}}.

verify_none is already the dist default. For a cert-free cluster, give every node the same secret:

%% sys.config
[
    {quic, [
        {dist, [
            {psks, #{<<"cluster">> => <<"32-byte-shared-secret-...">>}},
            {external_psk, {<<"cluster">>, <<"32-byte-shared-secret-...">>}},
            {verify, verify_none},
            {discovery_module, quic_discovery_static},
            {nodes, [
                {'node1@host1', {"192.168.1.1", 4433}},
                {'node2@host2', {"192.168.1.2", 4433}}
            ]}
        ]}
    ]}
].

cert_file / key_file may be omitted entirely. Per-peer identities go through quic_dist:set_connect_options/2. See QUIC_DIST.md.

Cost

The handshake negotiates TLS_AES_128_GCM_SHA256, which is the only suite offered, so there is no cipher choice to tune. AES-GCM runs on the AES-NI / ARM crypto extensions through OpenSSL on any current server CPU. If throughput is the reason you wanted to drop TLS, see PERFORMANCE.md: the cost that shows up in profiles is packet handling and syscalls, not the AEAD.

Verifying it

test/quic_trusted_network_SUITE.erl runs both configurations above through a recording UDP relay and asserts the echoed payload appears in no datagram in either direction:

rebar3 ct --suite=quic_trusted_network_SUITE

Cert-free distribution is covered by test/quic_dist_psk_SUITE.erl.