AJ

The vault's cold-chain attestation unit keeps a 64-bit chain register and speaks a terse line language. You may submit jobs of up to thirteen lines; each job runs on a unit of its own and returns whatever notes its lines produce. The unit lists its line letters and their operand ranges, not what they do.

A trace line shows you part of the register. A seal line reports the current seal when the register is clear; a manifest line releases the manifest to a register that matches the seal. The unit is re-cut every two minutes, and every cut has its own seal.

Start with GET / on the unit. The handout is the interface notes and a small client.

BLIND RATCHET - field interface

The vault's cold-chain attestation unit keeps a 64-bit chain register and speaks a terse line language over HTTP. Every team has its own unit: start your instance and use the http://<host>:<port>/ address it gives you.

Endpoints

GET  /      this unit's line set, operand ranges, limits and note formats (JSON)
POST /run   one job:  {"job": "<lines>"}

Jobs

• A job is at most 13 lines and at most 96 bytes. Lines are separated by a single LF (\n); one trailing LF is ignored.
• Each job runs on a unit of its own. Its notes come back when the whole job has finished.
• A letter line is a letter, a slash and an operand, as in x/7. Which letters your unit has, and which operands each takes, is in its GET /. Operands are decimal, 1 to 3 digits; leading zeros are accepted. One letter takes no operand.
• trace adds the note chain <8 hex digits>: part of the register.
• seal adds seal <16 hex digits> (the current cut's seal) when the register is clear, and locked otherwise.
• manifest adds manifest <text> when the register matches the current cut's seal, and locked otherwise.
• The unit is re-cut every 120 seconds. A job runs entirely in the cut in which it starts, and every cut has its own seal. GET / says when the next cut starts.
• If any line of a job is not valid, nothing runs: the answer is HTTP 400 {"error": "rejected", "line": k}, k being the first refused line (0 when the request is not a job at all).
• More than 20 jobs per second on one unit: HTTP 429 {"error": "busy"}.

Example exchanges

Recorded from a demonstration unit. Its letters are not yours, and no register value below means anything on your unit.

GET /
200 {"unit": "cold-chain attestation unit", "register_bits": 64, "lines": ["j/", "k/<0-63>", "n/<0-9>", "v/<1-31>", "trace", "seal", "manifest"], "operands": "decimal, 1 to 3 digits, leading zeros accepted", "job": {"max_lines": 13, "max_bytes": 96, "line_separator": "LF"}, "notes": {"trace": "chain <8 hex digits>", "seal": "seal <16 hex digits> | locked", "manifest": "manifest <text> | locked"}, "cut_s": 120, "next_cut_in_s": 78, "jobs_per_second": 20}

POST /run  {"job": "trace"}
200 {"notes": ["chain 253b5241"]}

POST /run  {"job": "v/05\ntrace"}
200 {"notes": ["chain 5d30f7f9"]}

POST /run  {"job": "trace\nk/64"}
400 {"error": "rejected", "line": 2}

client.py

python3 client.py http://<host>:<port>
python3 client.py http://<host>:<port> trace trace

Flag format: isfcr{…}