v0.0.6 - Tier-1 TCP listener + FIPS deployment documentation

documents/qubes_client_examples.md

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+# qubes_client_examples.md
+
+This document shows minimal caller-qube examples for invoking `nsigner --listen qrexec` through Qubes qrexec.
+
+For complete protocol details (framing, JSON-RPC, error handling), see `documents/CLIENT_IMPLEMENTATION.md`.
+
+---
+
+## 1) Shell example (`qrexec-client-vm` + framed JSON)
+
+This sends one `get_public_key` request and decodes one framed response.
+
+```bash
+#!/bin/sh
+set -eu
+
+TARGET_QUBE="nsigner-vault"
+SERVICE="qubes.NsignerRpc"
+REQ='{"id":"1","method":"get_public_key","params":[]}'
+
+python3 - "$TARGET_QUBE" "$SERVICE" "$REQ" <<'PY'
+import json
+import struct
+import subprocess
+import sys
+
+target, service, req_json = sys.argv[1], sys.argv[2], sys.argv[3]
+frame = struct.pack(">I", len(req_json.encode("utf-8"))) + req_json.encode("utf-8")
+
+p = subprocess.Popen(
+    ["qrexec-client-vm", target, service],
+    stdin=subprocess.PIPE,
+    stdout=subprocess.PIPE,
+)
+out, _ = p.communicate(frame)
+if p.returncode != 0:
+    raise SystemExit(f"qrexec-client-vm failed: {p.returncode}")
+if len(out) < 4:
+    raise SystemExit("short response (missing frame header)")
+
+n = struct.unpack(">I", out[:4])[0]
+payload = out[4:4+n]
+if len(payload) != n:
+    raise SystemExit("short response payload")
+
+print(json.dumps(json.loads(payload.decode("utf-8")), indent=2))
+PY
+```
+
+---
+
+## 2) Python example (explicit frame helpers over qrexec stdio)
+
+```python
+#!/usr/bin/env python3
+import json
+import struct
+import subprocess
+
+
+def frame_encode(obj: dict) -> bytes:
+    payload = json.dumps(obj, separators=(",", ":")).encode("utf-8")
+    return struct.pack(">I", len(payload)) + payload
+
+
+def frame_decode(buf: bytes) -> dict:
+    if len(buf) < 4:
+        raise ValueError("missing frame header")
+    n = struct.unpack(">I", buf[:4])[0]
+    payload = buf[4:4 + n]
+    if len(payload) != n:
+        raise ValueError("short frame payload")
+    return json.loads(payload.decode("utf-8"))
+
+
+def call_nsigner_qrexec(target_qube: str, request: dict) -> dict:
+    proc = subprocess.Popen(
+        ["qrexec-client-vm", target_qube, "qubes.NsignerRpc"],
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+    )
+    out, err = proc.communicate(frame_encode(request))
+    if proc.returncode != 0:
+        raise RuntimeError(f"qrexec failed ({proc.returncode}): {err.decode('utf-8', 'replace')}")
+    return frame_decode(out)
+
+
+if __name__ == "__main__":
+    req = {"id": "1", "method": "get_public_key", "params": []}
+    resp = call_nsigner_qrexec("nsigner-vault", req)
+    print(json.dumps(resp, indent=2))
+```