Wireshark's built-in HSMS dissector — written by network-protocol
authors who don't know us, didn't talk to us, and don't share
implementation details with secsgem-py — is a third independent codec
for our framing. If they parse our pcap without warnings, our HSMS
framing is wire-correct independently of both our internal tests and
the secsgem-py interop path.
interop/tshark_validate.sh:
- Boots secs_server on 127.0.0.1:5099 (away from the demo port)
- Captures the loopback wire traffic with tcpdump
- Runs secs_client through ~24 transactions plus Separate.req +
TCP FIN
- Parses the pcap with tshark -V using the HSMS dissector
- Asserts: no "Malformed Packet", no "Dissector bug", at least one
HSMS frame, expected tokens present (Select.req/rsp, Separate.req,
Data message), reports histogram (count by control type + distinct
S/F pairs)
Result against the demo: 69 HSMS frames dissected, 49 distinct
S/F pairs (S01F01..S16F28), all clean.
Dockerfile gains tshark + tcpdump. .gitea/workflows/ci.yml gains a
`tshark-dissector` job that runs this validator as part of every
push to main. README proof table grows to 6 commands.
VERIFICATION.md §1a documents a follow-up: round-trip the KAT
fixtures through secsgem-py to corroborate that the format codes
we used match an independent implementation. Strengthens the KAT
proof from "internally consistent" to "confirmed by a second
implementer who read the spec without talking to us."
Plan: VERIFICATION.md §2.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
