Replace new example with HasPublicKey method

examples/ble.py

@@ -1,88 +0,0 @@
-from __future__ import annotations
-
-TWO_MOST_SIGNIFICANT_BITS_MASK = 0b11000000
-
-
-def pubkey_to_ble(pubkey: bytes) -> tuple[bytes, bytes]:
-    assert len(pubkey) == 28
-
-    addr = bytearray(pubkey[:6])
-    addr[0] |= TWO_MOST_SIGNIFICANT_BITS_MASK
-
-    ad = bytes(
-        [
-            # apple company id
-            0x4C,
-            0x00,
-            # offline finding
-            0x12,
-            # offline finding data length
-            25,
-            # status
-            0b11100000,  # critically low battery
-            # remaining public key bytes
-            *pubkey[6:],
-            pubkey[0] >> 6,
-            0,  # hint
-        ],
-    )
-
-    return bytes(addr), ad
-
-
-def ble_to_pubkey(addr: bytes, ad: bytes) -> bytes:
-    assert len(addr) == 6
-    assert len(ad) == 29
-
-    assert ad[0:2] == bytes([0x4C, 0x00])
-    assert ad[2] == 0x12
-    assert ad[3] == 25
-
-    return bytes(
-        [
-            (addr[0] & (0xFF ^ TWO_MOST_SIGNIFICANT_BITS_MASK)) | (ad[27] << 6),
-            *addr[1:],
-            *ad[5:27],
-        ],
-    )
-
-
-if __name__ == "__main__":
-    import base64
-    import sys
-
-    USAGE = f"""Usage: {sys.argv[0]} <subcommand> <args>
-
-Subcommands:
-
-{sys.argv[0]} gen-pubkey <hex bt address (BE)> <hex ble ad data (BE)>
-{sys.argv[0]} gen-ble <base64 public key>"""
-
-    if len(sys.argv) < 2:
-        print(USAGE, file=sys.stderr)
-        sys.exit(1)
-
-    subcommand = sys.argv[1]
-
-    if subcommand == "gen-pubkey":
-        if len(sys.argv) != 4:
-            print(USAGE, file=sys.stderr)
-            sys.exit(1)
-
-        addr = bytes.fromhex(sys.argv[2])
-        ad = bytes.fromhex(sys.argv[3])
-
-        pubkey = ble_to_pubkey(addr, ad)
-        print(base64.b64encode(pubkey).decode())
-    elif subcommand == "gen-ble":
-        if len(sys.argv) != 3:
-            print(USAGE, file=sys.stderr)
-            sys.exit(1)
-
-        pubkey = base64.b64decode(sys.argv[2])
-        addr, ad = pubkey_to_ble(pubkey)
-
-        print(addr.hex(), ad.hex())
-    else:
-        print(USAGE, file=sys.stderr)
-        sys.exit(1)

findmy/keys.py

@@ -83,6 +83,25 @@ class HasPublicKey(HasHashedPublicKey, ABC):
         """See `HasHashedPublicKey.hashed_adv_key_bytes`."""
         return hashlib.sha256(self.adv_key_bytes).digest()
 
+    def ble_advertisement(self, status: int = 0, hint: int = 0) -> bytes:
+        """Return BLE advertisement data that represents this key."""
+        return bytes(
+            [
+                # apple company id
+                0x4C,
+                0x00,
+                # offline finding
+                0x12,
+                # offline finding data length
+                25,
+                status,
+                # remaining public key bytes
+                *self.adv_key_bytes[6:],
+                self.adv_key_bytes[0] >> 6,
+                hint,
+            ],
+        )
+
 
 class KeyPair(HasPublicKey):
     """A private-public keypair for a trackable FindMy accessory."""