294 lines
9.8 KiB
Python
294 lines
9.8 KiB
Python
# This file is part of the MicroPython project, http://micropython.org/
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#
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# The MIT License (MIT)
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#
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# Copyright (c) 2020-2021 Damien P. George
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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"""
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Utility to create compressed, encrypted and signed DFU files.
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"""
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import argparse
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import os
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import re
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import struct
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import sys
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import zlib
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sys.path.append(os.path.dirname(__file__) + "/../../../tools")
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import dfu
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try:
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import pyhy
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except ImportError:
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raise SystemExit(
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"ERROR: pyhy not found. Please install python pyhy for encrypted mboot support: pip3 install pyhy"
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)
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# Currently supported version of a packed DFU file.
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MBOOT_PACK_HEADER_VERSION = 1
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# Must match MBOOT_PACK_HYDRO_CONTEXT in mboot/pack.h
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MBOOT_PACK_HYDRO_CONTEXT = "mbootenc"
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# Must match enum in mboot/pack.h.
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MBOOT_PACK_CHUNK_META = 0
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MBOOT_PACK_CHUNK_FULL_SIG = 1
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MBOOT_PACK_CHUNK_FW_RAW = 2
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MBOOT_PACK_CHUNK_FW_GZIP = 3
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class Keys:
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def __init__(self, filename):
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self.filename = filename
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def generate(self):
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kp = pyhy.hydro_sign_keygen()
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self.sign_sk = kp.sk
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self.sign_pk = kp.pk
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self.secretbox = pyhy.hydro_secretbox_keygen()
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def _save_data(self, name, data, file_, hide=False):
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prefix = "//" if hide else ""
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data = ",".join("0x{:02x}".format(b) for b in data)
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file_.write("{}const uint8_t {}[] = {{{}}};\n".format(prefix, name, data))
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def _load_data(self, name, line):
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line = line.split(name + "[] = ")
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if len(line) != 2:
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raise Exception("malformed input keys: {}".format(line))
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data = line[1].strip()
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return bytes(int(value, 16) for value in data[1:-2].split(","))
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def save(self):
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with open(self.filename, "w") as f:
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self._save_data("mboot_pack_sign_secret_key", self.sign_sk, f, hide=True)
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self._save_data("mboot_pack_sign_public_key", self.sign_pk, f)
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self._save_data("mboot_pack_secretbox_key", self.secretbox, f)
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def load(self):
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with open(self.filename) as f:
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for line in f:
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for key, attr in (
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("mboot_pack_sign_secret_key", "sign_sk"),
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("mboot_pack_sign_public_key", "sign_pk"),
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("mboot_pack_secretbox_key", "secretbox"),
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):
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if key in line:
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setattr(self, attr, self._load_data(key, line))
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def dfu_read(filename):
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elems = []
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with open(filename, "rb") as f:
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hdr = f.read(11)
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sig, ver, size, num_targ = struct.unpack("<5sBIB", hdr)
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file_offset = 11
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for i in range(num_targ):
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hdr = f.read(274)
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sig, alt, has_name, name, t_size, num_elem = struct.unpack("<6sBi255sII", hdr)
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file_offset += 274
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file_offset_t = file_offset
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for j in range(num_elem):
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hdr = f.read(8)
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addr, e_size = struct.unpack("<II", hdr)
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data = f.read(e_size)
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elems.append((addr, data))
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file_offset += 8 + e_size
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if t_size != file_offset - file_offset_t:
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raise Exception("corrupt DFU {} {}".format(t_size, file_offset - file_offset_t))
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if size != file_offset:
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raise Exception("corrupt DFU {} {}".format(size, file_offset))
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hdr = f.read(16)
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hdr = struct.unpack("<HHHH3sBI", hdr)
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vid_pid = "0x{:04x}:0x{:04x}".format(hdr[2], hdr[1])
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return vid_pid, elems
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def compress(data):
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c = zlib.compressobj(level=9, memLevel=9, wbits=-15) # wsize=15, no header
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return c.compress(data) + c.flush()
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def encrypt(keys, data):
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return pyhy.hydro_secretbox_encrypt(data, 0, MBOOT_PACK_HYDRO_CONTEXT, keys.secretbox)
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def sign(keys, data):
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if not hasattr(keys, "sign_sk"):
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raise Exception("packing a dfu requires a secret key")
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return pyhy.hydro_sign_create(data, MBOOT_PACK_HYDRO_CONTEXT, keys.sign_sk)
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def pack_chunk(keys, format_, chunk_addr, chunk_payload):
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header = struct.pack(
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"<BBBBII", MBOOT_PACK_HEADER_VERSION, format_, 0, 0, chunk_addr, len(chunk_payload)
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)
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chunk = header + chunk_payload
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sig = sign(keys, chunk)
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chunk = chunk + sig
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return chunk
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def data_chunks(data, n):
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for i in range(0, len(data), n):
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yield data[i : i + n]
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def generate_keys(keys, args):
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keys.generate()
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keys.save()
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def pack_dfu(keys, args):
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chunk_size = int(args.chunk_size[0])
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# Load previously generated keys.
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keys.load()
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# Read the input DFU file.
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vid_pid, elems = dfu_read(args.infile[0])
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# Ensure firmware sections are processed in order of destination memory address.
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elems = sorted(elems, key=lambda e: e[0])
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# Build list of packed chunks.
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target = []
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full_fw = b""
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full_signature_payload = b""
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for address, fw in elems:
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# Update full firmware and full signature chunk.
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full_fw += fw
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full_signature_payload += struct.pack("<II", address, len(fw))
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# Split the firmware into chunks, encrypt and sign the chunks
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# then register them as individual DFU targets.
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for i, chunk in enumerate(data_chunks(fw, chunk_size)):
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chunk_addr = address + i * chunk_size
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if args.gzip:
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chunk = compress(chunk)
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chunk = encrypt(keys, chunk)
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chunk = pack_chunk(
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keys,
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MBOOT_PACK_CHUNK_FW_GZIP if args.gzip else MBOOT_PACK_CHUNK_FW_RAW,
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chunk_addr,
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chunk,
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)
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target.append({"address": chunk_addr, "data": chunk})
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# Add full signature to targets, at location following the last chunk.
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chunk_addr += chunk_size
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sig = sign(keys, full_fw)
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full_signature_payload += sig
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full_signature_chunk = pack_chunk(
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keys, MBOOT_PACK_CHUNK_FULL_SIG, chunk_addr, full_signature_payload
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)
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target.append({"address": chunk_addr, "data": full_signature_chunk})
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# Build the packed DFU file of all the encrypted and signed chunks.
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dfu.build(args.outfile[0], [target], vid_pid)
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# Verify the packed DFU file.
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verify_pack_dfu(keys, args.outfile[0])
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def verify_pack_dfu(keys, filename):
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"""Verify packed dfu file against keys. Gathers decrypted binary data."""
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full_sig = pyhy.hydro_sign(MBOOT_PACK_HYDRO_CONTEXT)
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_, elems = dfu_read(filename)
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base_addr = None
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binary_data = b""
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for addr, data in elems:
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if base_addr is None:
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base_addr = addr
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header = struct.unpack("<BBBBII", data[:12])
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chunk = data[12 : 12 + header[5]]
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sig = data[12 + header[5] :]
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sig_pass = pyhy.hydro_sign_verify(
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sig, data[:12] + chunk, MBOOT_PACK_HYDRO_CONTEXT, keys.sign_pk
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)
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assert sig_pass
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if header[1] == MBOOT_PACK_CHUNK_FULL_SIG:
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actual_sig = chunk[-64:]
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else:
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chunk = pyhy.hydro_secretbox_decrypt(
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chunk, 0, MBOOT_PACK_HYDRO_CONTEXT, keys.secretbox
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)
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assert chunk is not None
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if header[1] == MBOOT_PACK_CHUNK_FW_GZIP:
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chunk = zlib.decompress(chunk, wbits=-15)
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full_sig.update(chunk)
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assert addr == base_addr + len(binary_data)
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binary_data += chunk
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full_sig_pass = full_sig.final_verify(actual_sig, keys.sign_pk)
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assert full_sig_pass
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return [{"address": base_addr, "data": binary_data}]
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def unpack_dfu(keys, args):
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# Load previously generated keys.
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keys.load()
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# Build a DFU file from the decrypted binary data.
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data = verify_pack_dfu(keys, args.infile[0])
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dfu.build(args.outfile[0], [data])
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def main():
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cmd_parser = argparse.ArgumentParser(description="Build signed/encrypted DFU files")
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cmd_parser.add_argument("-k", "--keys", default="mboot_keys.h", help="filename for keys")
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subparsers = cmd_parser.add_subparsers()
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parser_gk = subparsers.add_parser("generate-keys", help="generate keys")
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parser_gk.set_defaults(func=generate_keys)
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parser_ed = subparsers.add_parser("pack-dfu", help="encrypt and sign a DFU file")
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parser_ed.add_argument("-z", "--gzip", action="store_true", help="compress chunks")
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parser_ed.add_argument("chunk_size", nargs=1, help="maximum size in bytes of each chunk")
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parser_ed.add_argument("infile", nargs=1, help="input DFU file")
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parser_ed.add_argument("outfile", nargs=1, help="output DFU file")
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parser_ed.set_defaults(func=pack_dfu)
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parser_dd = subparsers.add_parser("unpack-dfu", help="decrypt a signed/encrypted DFU file")
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parser_dd.add_argument("infile", nargs=1, help="input packed DFU file")
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parser_dd.add_argument("outfile", nargs=1, help="output DFU file")
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parser_dd.set_defaults(func=unpack_dfu)
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args = cmd_parser.parse_args()
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keys = Keys(args.keys)
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args.func(keys, args)
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if __name__ == "__main__":
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main()
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