nx9-chronoseal-rs/docs/API.md

ChronoSeal — API Reference

Base URL

All endpoints are relative to the server root. In development: http://localhost:3000. In production: your HTTPS domain via reverse proxy.

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Endpoints

POST /init

Initialise a new session. Called once per page load, immediately after the WASM module generates an Ed25519 keypair.

Request

POST /init
Content-Type: application/json

{
  "public_key": "hex-encoded 32-byte Ed25519 verifying key"
}

Field	Type	Description
public_key	string	Hex-encoded 32-byte Ed25519 verifying key generated by the WASM module

Response 200 OK

{
  "session_id":    "64-char hex string (32 bytes)",
  "salt":          "32-char hex string (16 bytes)",
  "opcodes_b64":   "base64-encoded VM program (8–16 opcodes)",
  "initial_hash":  "64-char hex string (32 bytes Blake3)",
  "expires_at":    1234567890123
}

Field	Type	Description
session_id	string	Opaque session identifier; include in every heartbeat
salt	string	Initial salt; used to compute H(0) and first H(1)
opcodes_b64	string	Base64 VM program; execute with run_program() on every heartbeat
initial_hash	string	H(0) = Blake3(session_id ║ pub_key ║ salt); the first prev_hash
expires_at	number	Unix timestamp in milliseconds; session expires after 30 minutes of inactivity

Error

Returns 500 Internal Server Error only on server-side failures (DB errors, invalid public key length). No meaningful error body is returned.

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POST /hb

Submit a heartbeat. Called every 12–25 seconds with uniform random jitter.

Request

POST /hb
Content-Type: application/json

{
  "session_id":   "64-char hex",
  "prev_hash":    "64-char hex",
  "timestamp":    1234567890123,
  "entropy_data": {
    "events": [
      { "x": 412.0, "y": 308.5, "t": 1234.567 },
      { "x": 415.2, "y": 310.1, "t": 1285.123 }
    ]
  },
  "stack_state": {
    "stack": [2971406957, 1234567890],
    "ip": 42
  },
  "fingerprint": {
    "aspectRatio":        "1.7777777778",
    "devicePixelRatio":   "2",
    "hardwareConcurrency": 8
  },
  "signature": "128-char hex Ed25519 signature"
}

Field	Type	Description
session_id	string	Session ID from /init
prev_hash	string	Hash chain head from previous heartbeat (or initial_hash for the first)
timestamp	number	Date.now() in milliseconds; must be within ±30s of server time
entropy_data.events	array	Mouse events since previous heartbeat; each has x, y (px), t (performance.now ms)
stack_state.stack	array	u32[] result of executing the VM program
stack_state.ip	number	Instruction pointer after execution
fingerprint.aspectRatio	string	(screen.width / screen.height).toFixed(10)
fingerprint.devicePixelRatio	string	String(window.devicePixelRatio)
fingerprint.hardwareConcurrency	number	navigator.hardwareConcurrency || 1
signature	string	Hex-encoded 64-byte Ed25519 signature over the canonical payload

Canonical Signing Payload

The client signs the following JSON object. Top-level keys must be sorted alphabetically. Nested object keys follow their natural serialisation order.

{
  "entropyData":  { "events": [{ "t": …, "x": …, "y": … }] },
  "fingerprint":  { "aspectRatio": "…", "devicePixelRatio": "…", "hardwareConcurrency": … },
  "prevHash":     "…",
  "sessionId":    "…",
  "stackState":   { "ip": …, "stack": […] },
  "timestamp":    …
}

Note: field names in the signing payload use camelCase (sessionId, prevHash, entropyData, stackState) while the request body uses snake_case (session_id, prev_hash, entropy_data, stack_state).

Response 200 OK — Accepted

{
  "status":    "ok",
  "next_salt": "32-char hex string (16 bytes)"
}

The client must:

1. Capture sentSalt = currentSalt before updating.
2. Set currentSalt = next_salt.
3. Compute prevHash = compute_next_hash(prevHash, timestamp, entropyJson, stackStateJson, sentSalt).

Response 200 OK — Rejected

{
  "status": "ok"
}

next_salt is absent. The response body is intentionally identical in structure. Rejections are silent — the caller cannot distinguish a validation failure from a rate limit hit or an expired session.

The client should log a warning and continue scheduling heartbeats (they will continue to fail until the page is reloaded and a new session is established).

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Validation Rules (Server-Side)

Heartbeats are rejected (silently) if any of the following checks fail:

Check	Condition for rejection
Rate limit	> 5 requests per 10-second window for this session_id
Session not found	session_id not in SQLite
Session expired	current_time_ms > expires_at
Signature invalid	Ed25519 verification fails against stored public key
Hash chain broken	hex(prev_hash) ≠ stored last_hash
Timestamp drift	|server_now_ms - timestamp| > 30 000
Insufficient mouse events	events.len() < 3
Insufficient mouse distance	total_dist < 10.0 px
Mouse speed too high	total_dist / total_time_ms > 2.0 px/ms
No mouse pauses	pause_count < 1
Invalid aspect ratio	ar < 0.5 or ar > 3.0
Invalid devicePixelRatio	dpr ≤ 0.0 or dpr > 5.0
Zero hardwareConcurrency	hardware_concurrency == 0

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Hash Chain Specification

H(0) = Blake3( session_id_bytes ║ pub_key_bytes ║ salt₀_bytes )

H(n) = Blake3(
    saltₙ₋₁_bytes
  ║ H(n-1)_bytes
  ║ timestamp_u64_le_bytes
  ║ Blake3( UTF-8( JSON(entropy_data) ) )
  ║ Blake3( UTF-8( JSON(stack_state)  ) )
)

All inputs are concatenated in the order shown. timestamp is encoded as a 64-bit unsigned integer in little-endian byte order. JSON serialisation of entropy_data and stack_state uses the field order defined by the shared Rust types (serde derive, no custom ordering).

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WASM API

The WASM module (antibot_wasm) exports the following functions to JavaScript:

Function	Signature	Description
generate_keypair()	() → string	Generate Ed25519 keypair; return hex public key. Private key stored in WASM memory.
get_public_key()	() → string	Return hex public key, or "" if not initialised.
sign_message(msg)	(string) → string	Sign UTF-8 string; return hex signature, or "" if not initialised.
compute_next_hash(prev, ts, entropy, stack, salt)	(string, u64, string, string, string) → string	Compute next Blake3 chain hash; all inputs/output hex or JSON strings.
run_program(b64)	(string) → JsValue	Execute base64 VM program; return { stack: u32[], ip: number }.

All functions return empty strings on error rather than panicking. Callers must check for empty return values before using the result.