implement device signing binary frames and sign() command for on-device signing.

examples/ble_sign_example.py

@@ -0,0 +1,96 @@
+#!/usr/bin/env python3
+"""
+Example: Sign arbitrary data with a MeshCore device over BLE.
+
+The device performs signing on its private key via the CMD_SIGN_* flow:
+- sign_start(): initializes a signing session and returns max buffer size (8KB on firmware)
+- sign_data(): streams one or more data chunks
+- sign_finish(): returns the signature
+"""
+
+import argparse
+import asyncio
+from pathlib import Path
+import sys
+from textwrap import wrap
+
+# Ensure local src/ is on path when running from repo root
+repo_root = Path(__file__).resolve().parents[1]
+src_path = repo_root / "src"
+if src_path.exists():
+    sys.path.insert(0, str(src_path))
+
+from meshcore import MeshCore, EventType
+
+
+async def main():
+    parser = argparse.ArgumentParser(
+        description="Sign data using a MeshCore device over BLE"
+    )
+    parser.add_argument(
+        "-a",
+        "--addr",
+        help="BLE address of the device (optional, will scan if not provided)",
+    )
+    parser.add_argument(
+        "-p",
+        "--pin",
+        help="PIN for BLE pairing (optional)",
+    )
+    parser.add_argument(
+        "-d",
+        "--data",
+        default="Hello from meshcore_py!",
+        help="ASCII data to sign (will be UTF-8 encoded)",
+    )
+    parser.add_argument(
+        "--chunk-size",
+        type=int,
+        default=512,
+        help="Chunk size to stream to the device (bytes)",
+    )
+    parser.add_argument(
+        "--debug",
+        action="store_true",
+        help="Enable debug logging",
+    )
+    args = parser.parse_args()
+
+    meshcore = None
+    try:
+        print("Connecting to MeshCore device...")
+        meshcore = await MeshCore.create_ble(address=args.addr, pin=args.pin, debug=args.debug)
+        print("✅ Connected.")
+
+        data_bytes = args.data.encode("utf-8")
+        sig_evt = await meshcore.commands.sign(data_bytes, chunk_size=max(1, args.chunk_size))
+        if sig_evt.type == EventType.ERROR:
+            raise RuntimeError(f"sign failed: {sig_evt.payload}")
+        signature = sig_evt.payload.get("signature", b"")
+        print(f"Signature ({len(signature)} bytes):")
+        # Pretty-print hex in 32-byte lines
+        hex_sig = signature.hex()
+        for line in wrap(hex_sig, 64):
+            print(line)
+
+        print("\nSigning flow completed!")
+
+    except ConnectionError as e:
+        print(f"❌ Failed to connect: {e}")
+        return 1
+    except Exception as e:
+        print(f"❌ Error: {e}")
+        return 1
+    finally:
+        if meshcore:
+            await meshcore.disconnect()
+            print("Disconnected.")
+
+
+if __name__ == "__main__":
+    try:
+        sys.exit(asyncio.run(main()))
+    except KeyboardInterrupt:
+        print("\nInterrupted by user")
+        sys.exit(1)
+