2 files changed, 221 insertions, 0 deletions

diff --git a/reversing_tools/abbott/encrypted_setup_extractor.py b/reversing_tools/abbott/encrypted_setup_extractor.py
new file mode 100644
index 0000000..cc57f0f
--- /dev/null
+++ b/reversing_tools/abbott/encrypted_setup_extractor.py
@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+#
+# SPDX-FileCopyrightText: © 2019 The usbmon-tools Authors
+# SPDX-FileCopyrightText: © 2020 The glucometerutils Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+import logging
+import sys
+
+import construct
+import usbmon
+import usbmon.pcapng
+
+_SERIAL_NUMBER_RESPONSE_TYPE = 0x06
+_ENCRYPTION_SETUP_REQ_TYPE = 0x14
+_ENCRYPTION_SETUP_RESP_TYPE = 0x33
+
+
+_START_AUTHORIZE_CMD = 0x11
+_CHALLENGE_CMD = 0x16
+_CHALLENGE_RESPONSE_CMD = 0x17
+
+
+_ABBOTT_VENDOR_ID = 0x1A61
+_LIBRE2_PRODUCT_ID = 0x3950
+
+_SERIAL_NO = construct.Struct(
+    message_type=construct.Const(_SERIAL_NUMBER_RESPONSE_TYPE, construct.Byte),
+    length=construct.Const(14, construct.Byte),
+    serial_number=construct.PaddedString(13, "ascii"),
+    termination=construct.Const(0, construct.Byte),
+)
+
+_CHALLENGE = construct.Struct(
+    message_type=construct.Const(_ENCRYPTION_SETUP_RESP_TYPE, construct.Byte),
+    length=construct.Const(16, construct.Byte),
+    subcmd=construct.Const(_CHALLENGE_CMD, construct.Byte),
+    challenge=construct.Bytes(8),
+    iv=construct.Bytes(7),
+)
+
+_CHALLENGE_RESPONSE = construct.Struct(
+    message_type=construct.Const(_ENCRYPTION_SETUP_REQ_TYPE, construct.Byte),
+    length=construct.Const(26, construct.Byte),
+    subcmd=construct.Const(_CHALLENGE_RESPONSE_CMD, construct.Byte),
+    challenge_response_encrypted=construct.Bytes(16),
+    const=construct.Const(1, construct.Byte),
+    mac=construct.Bytes(8),
+)
+
+
+def main():
+    if sys.version_info < (3, 7):
+        raise Exception("Unsupported Python version, please use at least Python 3.7.")
+
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument(
+        "--device_address",
+        action="store",
+        type=str,
+        help=(
+            "Device address (busnum.devnum) of the device to extract capture"
+            " of. If none provided, device descriptors will be relied on."
+        ),
+    )
+
+    parser.add_argument(
+        "--vlog",
+        action="store",
+        required=False,
+        type=int,
+        help=(
+            "Python logging level. See the levels at"
+            " https://docs.python.org/3/library/logging.html#logging-levels"
+        ),
+    )
+
+    parser.add_argument(
+        "pcap_files",
+        action="store",
+        type=argparse.FileType(mode="rb"),
+        help="Path to the pcapng file with the USB capture.",
+        nargs="+",
+    )
+
+    args = parser.parse_args()
+
+    logging.basicConfig(level=args.vlog)
+
+    for pcap_file in args.pcap_files:
+        session = usbmon.pcapng.parse_stream(pcap_file, retag_urbs=False)
+
+        if not args.device_address:
+            for descriptor in session.device_descriptors.values():
+                if (
+                    descriptor.vendor_id == _ABBOTT_VENDOR_ID
+                    and descriptor.product_id == _LIBRE2_PRODUCT_ID
+                ):
+                    if (
+                        args.device_address
+                        and args.device_address != descriptor.address
+                    ):
+                        raise Exception(
+                            "Multiple Libre2 devices present in capture, please"
+                            " provide a --device_address flag."
+                        )
+                    device_address = descriptor.address
+        else:
+            device_address = descriptor.address
+
+        descriptor = session.device_descriptors.get(device_address, None)
+        if descriptor:
+            assert descriptor.vendor_id == _ABBOTT_VENDOR_ID
+            assert descriptor.product_id == _LIBRE2_PRODUCT_ID
+
+        serial_number = "UNKNOWN"
+        challenge = "UNKNOWN"
+        iv = "UNKNOWN"
+        encrypted_challenge = "UNKNOWN"
+        mac = "UNKNOWN"
+
+        for first, second in session.in_pairs():
+            # Ignore stray callbacks/errors.
+            if not first.type == usbmon.constants.PacketType.SUBMISSION:
+                continue
+
+            if not first.address.startswith(f"{device_address}."):
+                # No need to check second, they will be linked.
+                continue
+
+            if first.xfer_type == usbmon.constants.XferType.INTERRUPT:
+                pass
+            elif (
+                first.xfer_type == usbmon.constants.XferType.CONTROL
+                and not first.setup_packet
+                or first.setup_packet.type == usbmon.setup.Type.CLASS
+            ):
+                pass
+            else:
+                continue
+
+            if first.direction == usbmon.constants.Direction.OUT:
+                packet = first
+            else:
+                packet = second
+
+            if not packet.payload:
+                continue
+
+            assert len(packet.payload) >= 2
+
+            message_type = packet.payload[0]
+
+            if message_type == _SERIAL_NUMBER_RESPONSE_TYPE:
+                obj = _SERIAL_NO.parse(packet.payload)
+                serial_number = obj.serial_number
+            elif (
+                message_type == _ENCRYPTION_SETUP_RESP_TYPE
+                and packet.payload[2] == _CHALLENGE_CMD
+            ):
+                obj = _CHALLENGE.parse(packet.payload)
+                challenge = obj.challenge.hex()
+                iv = obj.iv.hex()
+            elif (
+                message_type == _ENCRYPTION_SETUP_REQ_TYPE
+                and packet.payload[2] == _CHALLENGE_RESPONSE_CMD
+            ):
+                obj = _CHALLENGE_RESPONSE.parse(packet.payload)
+                encrypted_challenge = obj.challenge_response_encrypted.hex()
+                mac = obj.mac.hex()
+
+        print(f"{serial_number},{challenge},{iv},{encrypted_challenge},{mac}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/reversing_tools/abbott/extract_freestyle.py b/reversing_tools/abbott/extract_freestyle.py
index 006b393..52eeaf2 100755
--- a/reversing_tools/abbott/extract_freestyle.py
+++ b/reversing_tools/abbott/extract_freestyle.py
@@ -33,6 +33,13 @@ _UNENCRYPTED_TYPES = (
     _KEEPALIVE_TYPE,
 )
 
+_ENCRYPTION_SETUP_TYPES = (0x14, 0x33)
+
+_START_AUTHORIZE_CMD = 0x11
+_CHALLENGE_CMD = 0x16
+_CHALLENGE_RESPONSE_CMD = 0x17
+_CHALLENGE_ACCEPTED_CMD = 0x18
+
 _ABBOTT_VENDOR_ID = 0x1A61
 _LIBRE2_PRODUCT_ID = 0x3950
 
@@ -70,6 +77,15 @@ def main():
     )
 
     parser.add_argument(
+        "--verbose-encryption-setup",
+        action="store_true",
+        help=(
+            "Whether to parse encryption setup commands and printing their component"
+            " together with the raw messsage."
+        ),
+    )
+
+    parser.add_argument(
         "--vlog",
         action="store",
         required=False,
@@ -173,6 +189,32 @@ def main():
 
             message_type = f"x{message_type:02x}"
             message = parsed.encrypted_message
+        elif args.verbose_encryption_setup and message_type in _ENCRYPTION_SETUP_TYPES:
+            message_length = packet.payload[1]
+            message_end_idx = 2 + message_length
+            message = packet.payload[2:message_end_idx]
+
+            if message[0] == _START_AUTHORIZE_CMD:
+                message_metadata.append("START_AUTHORIZE")
+            elif message[0] == _CHALLENGE_CMD:
+                message_metadata.append("CHALLENGE")
+                challenge = message[1:9]
+                iv = message[9:16]
+                message_metadata.append(f"CHALLENGE={challenge.hex()}")
+                message_metadata.append(f"IV={iv.hex()}")
+            elif message[0] == _CHALLENGE_RESPONSE_CMD:
+                message_metadata.append("CHALLENGE_RESPONSE")
+                encrypted_challenge = message[1:17]
+                challenge_mac = message[18:26]
+                message_metadata.append(
+                    f"ENCRYPTED_CHALLENGE={encrypted_challenge.hex()}"
+                )
+                message_metadata.append(f"MAC={challenge_mac.hex()}")
+            elif message[0] == _CHALLENGE_ACCEPTED_CMD:
+                message_metadata.append("CHALLENGE_ACCEPTED")
+
+            message_metadata.append(f"RAW_LENGTH={message_length}")
+            message_type = f" {message_type:02x}"
         else:
             message_length = packet.payload[1]
             message_metadata.append(f"LENGTH={message_length}")