| --- |
| license: cc-by-4.0 |
| task_categories: |
| - other |
| tags: |
| - network-traffic |
| - side-channel |
| - llm-security |
| - tls |
| - timing |
| pretty_name: token_break — LLM streaming traffic side-channel captures |
| --- |
| |
| # token_break — LLM streaming traffic captures |
| |
| Packet captures (`*.pcap`) and paired client-side streaming logs (`*.jsonl`) from |
| commercial LLM streaming APIs, collected to study which side channels survive |
| provider-side **obfuscation** (TLS record padding). Companion to the private |
| analysis repo `token_break` (see its `FINDINGS.md` / `HANDOFF.md`). |
|
|
| **No secrets and no prompt text are included.** The `jsonl` logs record only |
| per-chunk *metadata* (character/token counts and timing), never the token strings. |
|
|
| ## Files |
|
|
| | pcap | paired jsonl | provider / model | notes | |
| |------|--------------|------------------|-------| |
| | `orcap_oai4o.pcap` | `stream_oai4o.jsonl` | OpenAI native, `gpt-4o` | **primary** — used for the length/count/uplink results | |
| | `orcap_oai54.pcap` | `stream_oai54.jsonl` | OpenAI Responses, `gpt-5.4` | **primary** — reasoning model, timing/TSval | |
| | `orcap_gpt54.pcap` | `stream_gpt54.jsonl` | OpenRouter → `openai/gpt-5.4` | exploratory | |
| | `orcap.pcap`, `orcap_full.pcap` | `stream_or_pcap.jsonl`, `stream_or_pcap_full.jsonl` | OpenRouter → `openai/gpt-4o` | earlier exploration | |
| | — | `stream_or_gpt4o_n20.jsonl`, `stream_or_repeat.jsonl` | OpenRouter → `openai/gpt-4o` | earlier runs (client logs only) | |
|
|
| `uc_prompts.jsonl` — the **exact prompt set** used for every capture above (60 |
| prompts sampled from UltraChat). One JSON object per line: `{"prompt": "..."}`. |
| **This is the file `prompt_idx` indexes into** (0-based line number). You must use |
| *this* copy — re-sampling UltraChat would misalign `prompt_idx` with the published |
| pcaps/jsonl. Analysis scripts default to `/tmp/uc_prompts.jsonl`; pass this file's |
| path instead (e.g. `analyze_uplink_prompt.py <pcap> <jsonl> data/uc_prompts.jsonl`). |
| |
| Server→client TLS Application-Data record counts (from the VM): `orcap_oai54` ≈ 5300, |
| `orcap_oai4o` ≈ 3000 packets. |
| |
| ## jsonl schema |
| |
| One JSON object per request: |
| |
| ```jsonc |
| { |
| "prompt_idx": 0, "rep": 0, |
| "provider": "openai", "model": "gpt-4o", |
| "wall_start": 1788833190.43, "wall_end": 1788833194.36, // client CLOCK_REALTIME (shared with pcap) |
| "n_chunks": 249, |
| "total_time_s": 3.90, "ttft_s": 1.55, |
| "total_tokens": 249, "total_chars": 1427, |
| "chunks": [ |
| { "t": 0.12, "dt_ms": 8.3, "ntok": 1, "nchar": 4 } // t = offset from wall_start; nchar = char length (NO text) |
| ] |
| } |
| ``` |
| |
| `prompt_idx` = 0-based line number in `uc_prompts.jsonl` (the prompt that produced |
| this record). `rep` = repeat index when a prompt was sent more than once. |
| |
| The client and `tcpdump` ran on the **same VM**, so `wall_start` + `chunk.t` share |
| one clock with the pcap timestamps — this is what lets you align client tokens to |
| server TLS records. |
| |
| ## How to align pcap ↔ jsonl |
| |
| Extract server→client Application-Data records with `tshark`: |
| |
| ```bash |
| tshark -r orcap_oai54.pcap \ |
| -Y "tcp.srcport==443 && tls.record.opaque_type==23" \ |
| -T fields -e frame.time_epoch -e tls.record.length \ |
| -e tcp.options.timestamp.tsval |
| ``` |
| |
| then match record times against `wall_start + chunk.t` from the jsonl. See the |
| analysis scripts in the code repo (`scripts/analyze/`). |
| |
| ## Known caveats |
| |
| - Captured on one VM close to the provider → **sub-millisecond path jitter**; timing |
| results assume this clean path. |
| - `chunks` carry `nchar` only, **not token text** → structure/boundary fingerprinting |
| needs re-collection with text logged. |
| - OpenRouter runs proxy to OpenAI models and may differ from native endpoints. |
| |
