# Copyright 2018 Nordic Semiconductor ASA # Copyright 2017-2020 Linaro Limited # Copyright 2019-2024 Arm Limited # # SPDX-License-Identifier: Apache-2.0 # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """ Image signing and management. """ from . import version as versmod from .boot_record import create_sw_component_data import click import copy from enum import Enum import array from intelhex import IntelHex import hashlib import array import os.path import struct from enum import Enum import click from cryptography.exceptions import InvalidSignature from cryptography.hazmat.backends import default_backend from cryptography.hazmat.primitives import hashes, hmac from cryptography.hazmat.primitives.asymmetric import ec, padding from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes from cryptography.hazmat.primitives.kdf.hkdf import HKDF from cryptography.hazmat.primitives.serialization import Encoding, PublicFormat from intelhex import IntelHex from . import version as versmod, keys from .boot_record import create_sw_component_data from .keys import rsa, ecdsa, x25519 from collections import namedtuple IMAGE_MAGIC = 0x96f3b83d IMAGE_HEADER_SIZE = 32 BIN_EXT = "bin" INTEL_HEX_EXT = "hex" DEFAULT_MAX_SECTORS = 128 DEFAULT_MAX_ALIGN = 8 DEP_IMAGES_KEY = "images" DEP_VERSIONS_KEY = "versions" MAX_SW_TYPE_LENGTH = 12 # Bytes # Image header flags. IMAGE_F = { 'PIC': 0x0000001, 'ENCRYPTED_AES128': 0x0000004, 'ENCRYPTED_AES256': 0x0000008, 'NON_BOOTABLE': 0x0000010, 'RAM_LOAD': 0x0000020, 'ROM_FIXED': 0x0000100, 'COMPRESSED_LZMA1': 0x0000200, 'COMPRESSED_LZMA2': 0x0000400, 'COMPRESSED_ARM_THUMB': 0x0000800, } TLV_VALUES = { 'KEYHASH': 0x01, 'PUBKEY': 0x02, 'SHA256': 0x10, 'SHA384': 0x11, 'SHA512': 0x12, 'RSA2048': 0x20, 'ECDSASIG': 0x22, 'RSA3072': 0x23, 'ED25519': 0x24, 'SIG_PURE': 0x25, 'ENCRSA2048': 0x30, 'ENCKW': 0x31, 'ENCEC256': 0x32, 'ENCX25519': 0x33, 'DEPENDENCY': 0x40, 'SEC_CNT': 0x50, 'BOOT_RECORD': 0x60, 'DECOMP_SIZE': 0x70, 'DECOMP_SHA': 0x71, 'DECOMP_SIGNATURE': 0x72, } TLV_SIZE = 4 TLV_INFO_SIZE = 4 TLV_INFO_MAGIC = 0x6907 TLV_PROT_INFO_MAGIC = 0x6908 TLV_VENDOR_RES_MIN = 0x00a0 TLV_VENDOR_RES_MAX = 0xfffe STRUCT_ENDIAN_DICT = { 'little': '<', 'big': '>' } VerifyResult = Enum('VerifyResult', ['OK', 'INVALID_MAGIC', 'INVALID_TLV_INFO_MAGIC', 'INVALID_HASH', 'INVALID_SIGNATURE', 'KEY_MISMATCH']) def align_up(num, align): assert (align & (align - 1) == 0) and align != 0 return (num + (align - 1)) & ~(align - 1) class TLV(): def __init__(self, endian, magic=TLV_INFO_MAGIC): self.magic = magic self.buf = bytearray() self.endian = endian def __len__(self): return TLV_INFO_SIZE + len(self.buf) def add(self, kind, payload): """ Add a TLV record. Kind should be a string found in TLV_VALUES above. """ e = STRUCT_ENDIAN_DICT[self.endian] if isinstance(kind, int): if not TLV_VENDOR_RES_MIN <= kind <= TLV_VENDOR_RES_MAX: msg = "Invalid custom TLV type value '0x{:04x}', allowed " \ "value should be between 0x{:04x} and 0x{:04x}".format( kind, TLV_VENDOR_RES_MIN, TLV_VENDOR_RES_MAX) raise click.UsageError(msg) buf = struct.pack(e + 'HH', kind, len(payload)) else: buf = struct.pack(e + 'BBH', TLV_VALUES[kind], 0, len(payload)) self.buf += buf self.buf += payload def get(self): if len(self.buf) == 0: return bytes() e = STRUCT_ENDIAN_DICT[self.endian] header = struct.pack(e + 'HH', self.magic, len(self)) return header + bytes(self.buf) SHAAndAlgT = namedtuple('SHAAndAlgT', ['sha', 'alg']) TLV_SHA_TO_SHA_AND_ALG = { TLV_VALUES['SHA256'] : SHAAndAlgT('256', hashlib.sha256), TLV_VALUES['SHA384'] : SHAAndAlgT('384', hashlib.sha384), TLV_VALUES['SHA512'] : SHAAndAlgT('512', hashlib.sha512), } USER_SHA_TO_ALG_AND_TLV = { 'auto' : (hashlib.sha256, 'SHA256'), '256' : (hashlib.sha256, 'SHA256'), '384' : (hashlib.sha384, 'SHA384'), '512' : (hashlib.sha512, 'SHA512') } def is_sha_tlv(tlv): return tlv in TLV_SHA_TO_SHA_AND_ALG.keys() def tlv_sha_to_sha(tlv): return TLV_SHA_TO_SHA_AND_ALG[tlv].sha # Auto selecting hash algorithm for type(key) ALLOWED_KEY_SHA = { keys.ECDSA384P1 : ['384'], keys.ECDSA384P1Public : ['384'], keys.ECDSA256P1 : ['256'], keys.RSA : ['256'], # This two are set to 256 for compatibility, the right would be 512 keys.Ed25519 : ['256', '512'], keys.X25519 : ['256', '512'] } ALLOWED_PURE_KEY_SHA = { keys.Ed25519 : ['512'] } ALLOWED_PURE_SIG_TLVS = [ TLV_VALUES['ED25519'] ] def key_and_user_sha_to_alg_and_tlv(key, user_sha, is_pure = False): """Matches key and user requested sha to sha alogrithm and TLV name. The returned tuple will contain hash functions and TVL name. The function is designed to succeed or completely fail execution, as providing incorrect pair here basically prevents doing any more work. """ if key is None: # If key is none, we allow whatever user has selected for sha return USER_SHA_TO_ALG_AND_TLV[user_sha] # If key is not None, then we have to filter hash to only allowed allowed = None allowed_key_ssh = ALLOWED_PURE_KEY_SHA if is_pure else ALLOWED_KEY_SHA try: allowed = allowed_key_ssh[type(key)] except KeyError: raise click.UsageError("Colud not find allowed hash algorithms for {}" .format(type(key))) # Pure enforces auto, and user selection is ignored if user_sha == 'auto' or is_pure: return USER_SHA_TO_ALG_AND_TLV[allowed[0]] if user_sha in allowed: return USER_SHA_TO_ALG_AND_TLV[user_sha] raise click.UsageError("Key {} can not be used with --sha {}; allowed sha are one of {}" .format(key.sig_type(), user_sha, allowed)) def get_digest(tlv_type, hash_region): sha = TLV_SHA_TO_SHA_AND_ALG[tlv_type].alg() sha.update(hash_region) return sha.digest() def tlv_matches_key_type(tlv_type, key): """Check if provided key matches to TLV record in the image""" try: # We do not need the result here, and the key_and_user_sha_to_alg_and_tlv # will either succeed finding match or rise exception, so on success we # return True, on exception we return False. _, _ = key_and_user_sha_to_alg_and_tlv(key, tlv_sha_to_sha(tlv_type)) return True except: pass return False class Image: def __init__(self, version=None, header_size=IMAGE_HEADER_SIZE, pad_header=False, pad=False, confirm=False, align=1, slot_size=0, max_sectors=DEFAULT_MAX_SECTORS, overwrite_only=False, endian="little", load_addr=0, rom_fixed=None, erased_val=None, save_enctlv=False, security_counter=None, max_align=None, non_bootable=False): if load_addr and rom_fixed: raise click.UsageError("Can not set rom_fixed and load_addr at the same time") self.image_hash = None self.image_size = None self.signature = None self.version = version or versmod.decode_version("0") self.header_size = header_size self.pad_header = pad_header self.pad = pad self.confirm = confirm self.align = align self.slot_size = slot_size self.max_sectors = max_sectors self.overwrite_only = overwrite_only self.endian = endian self.base_addr = None self.load_addr = 0 if load_addr is None else load_addr self.rom_fixed = rom_fixed self.erased_val = 0xff if erased_val is None else int(erased_val, 0) self.payload = [] self.infile_data = [] self.enckey = None self.save_enctlv = save_enctlv self.enctlv_len = 0 self.max_align = max(DEFAULT_MAX_ALIGN, align) if max_align is None else int(max_align) self.non_bootable = non_bootable if self.max_align == DEFAULT_MAX_ALIGN: self.boot_magic = bytes([ 0x77, 0xc2, 0x95, 0xf3, 0x60, 0xd2, 0xef, 0x7f, 0x35, 0x52, 0x50, 0x0f, 0x2c, 0xb6, 0x79, 0x80, ]) else: lsb = self.max_align & 0x00ff msb = (self.max_align & 0xff00) >> 8 align = bytes([msb, lsb]) if self.endian == "big" else bytes([lsb, msb]) self.boot_magic = align + bytes([0x2d, 0xe1, 0x5d, 0x29, 0x41, 0x0b, 0x8d, 0x77, 0x67, 0x9c, 0x11, 0x0f, 0x1f, 0x8a, ]) if security_counter == 'auto': # Security counter has not been explicitly provided, # generate it from the version number self.security_counter = ((self.version.major << 24) + (self.version.minor << 16) + self.version.revision) else: self.security_counter = security_counter def __repr__(self): return "".format( self.version, self.header_size, self.security_counter, self.base_addr if self.base_addr is not None else "N/A", self.load_addr, self.align, self.slot_size, self.max_sectors, self.overwrite_only, self.endian, self.__class__.__name__, len(self.payload)) def load(self, path): """Load an image from a given file""" ext = os.path.splitext(path)[1][1:].lower() try: if ext == INTEL_HEX_EXT: ih = IntelHex(path) self.infile_data = ih.tobinarray() self.payload = copy.copy(self.infile_data) self.base_addr = ih.minaddr() else: with open(path, 'rb') as f: self.infile_data = f.read() self.payload = copy.copy(self.infile_data) except FileNotFoundError: raise click.UsageError("Input file not found") self.image_size = len(self.payload) # Add the image header if needed. if self.pad_header and self.header_size > 0: if self.base_addr: # Adjust base_addr for new header self.base_addr -= self.header_size self.payload = bytes([self.erased_val] * self.header_size) + \ self.payload self.check_header() def load_compressed(self, data, compression_header): """Load an image from buffer""" self.payload = compression_header + data self.image_size = len(self.payload) # Add the image header if needed. if self.pad_header and self.header_size > 0: if self.base_addr: # Adjust base_addr for new header self.base_addr -= self.header_size self.payload = bytes([self.erased_val] * self.header_size) + \ self.payload self.check_header() def save(self, path, hex_addr=None): """Save an image from a given file""" ext = os.path.splitext(path)[1][1:].lower() if ext == INTEL_HEX_EXT: # input was in binary format, but HEX needs to know the base addr if self.base_addr is None and hex_addr is None: raise click.UsageError("No address exists in input file " "neither was it provided by user") h = IntelHex() if hex_addr is not None: self.base_addr = hex_addr h.frombytes(bytes=self.payload, offset=self.base_addr) if self.pad: trailer_size = self._trailer_size(self.align, self.max_sectors, self.overwrite_only, self.enckey, self.save_enctlv, self.enctlv_len) trailer_addr = (self.base_addr + self.slot_size) - trailer_size if self.confirm and not self.overwrite_only: magic_align_size = align_up(len(self.boot_magic), self.max_align) image_ok_idx = -(magic_align_size + self.max_align) flag = bytearray([self.erased_val] * self.max_align) flag[0] = 0x01 # image_ok = 0x01 h.puts(trailer_addr + trailer_size + image_ok_idx, bytes(flag)) h.puts(trailer_addr + (trailer_size - len(self.boot_magic)), bytes(self.boot_magic)) h.tofile(path, 'hex') else: if self.pad: self.pad_to(self.slot_size) with open(path, 'wb') as f: f.write(self.payload) def check_header(self): if self.header_size > 0 and not self.pad_header: if any(v != 0 for v in self.payload[0:self.header_size]): raise click.UsageError("Header padding was not requested and " "image does not start with zeros") def check_trailer(self): if self.slot_size > 0: tsize = self._trailer_size(self.align, self.max_sectors, self.overwrite_only, self.enckey, self.save_enctlv, self.enctlv_len) padding = self.slot_size - (len(self.payload) + tsize) if padding < 0: msg = "Image size (0x{:x}) + trailer (0x{:x}) exceeds " \ "requested size 0x{:x}".format( len(self.payload), tsize, self.slot_size) raise click.UsageError(msg) def ecies_hkdf(self, enckey, plainkey): if isinstance(enckey, ecdsa.ECDSA256P1Public): newpk = ec.generate_private_key(ec.SECP256R1(), default_backend()) shared = newpk.exchange(ec.ECDH(), enckey._get_public()) else: newpk = X25519PrivateKey.generate() shared = newpk.exchange(enckey._get_public()) derived_key = HKDF( algorithm=hashes.SHA256(), length=48, salt=None, info=b'MCUBoot_ECIES_v1', backend=default_backend()).derive(shared) encryptor = Cipher(algorithms.AES(derived_key[:16]), modes.CTR(bytes([0] * 16)), backend=default_backend()).encryptor() cipherkey = encryptor.update(plainkey) + encryptor.finalize() mac = hmac.HMAC(derived_key[16:], hashes.SHA256(), backend=default_backend()) mac.update(cipherkey) ciphermac = mac.finalize() if isinstance(enckey, ecdsa.ECDSA256P1Public): pubk = newpk.public_key().public_bytes( encoding=Encoding.X962, format=PublicFormat.UncompressedPoint) else: pubk = newpk.public_key().public_bytes( encoding=Encoding.Raw, format=PublicFormat.Raw) return cipherkey, ciphermac, pubk def create(self, key, public_key_format, enckey, dependencies=None, sw_type=None, custom_tlvs=None, compression_tlvs=None, compression_type=None, encrypt_keylen=128, clear=False, fixed_sig=None, pub_key=None, vector_to_sign=None, user_sha='auto', is_pure=False): self.enckey = enckey # key decides on sha, then pub_key; of both are none default is used check_key = key if key is not None else pub_key hash_algorithm, hash_tlv = key_and_user_sha_to_alg_and_tlv(check_key, user_sha, is_pure) # Calculate the hash of the public key if key is not None: pub = key.get_public_bytes() sha = hash_algorithm() sha.update(pub) pubbytes = sha.digest() elif pub_key is not None: if hasattr(pub_key, 'sign'): print(os.path.basename(__file__) + ": sign the payload") pub = pub_key.get_public_bytes() sha = hash_algorithm() sha.update(pub) pubbytes = sha.digest() else: pubbytes = bytes(hashlib.sha256().digest_size) protected_tlv_size = 0 if self.security_counter is not None: # Size of the security counter TLV: header ('HH') + payload ('I') # = 4 + 4 = 8 Bytes protected_tlv_size += TLV_SIZE + 4 if sw_type is not None: if len(sw_type) > MAX_SW_TYPE_LENGTH: msg = "'{}' is too long ({} characters) for sw_type. Its " \ "maximum allowed length is 12 characters.".format( sw_type, len(sw_type)) raise click.UsageError(msg) image_version = (str(self.version.major) + '.' + str(self.version.minor) + '.' + str(self.version.revision)) # The image hash is computed over the image header, the image # itself and the protected TLV area. However, the boot record TLV # (which is part of the protected area) should contain this hash # before it is even calculated. For this reason the script fills # this field with zeros and the bootloader will insert the right # value later. digest = bytes(hash_algorithm().digest_size) # Create CBOR encoded boot record boot_record = create_sw_component_data(sw_type, image_version, hash_tlv, digest, pubbytes) protected_tlv_size += TLV_SIZE + len(boot_record) if dependencies is not None: # Size of a Dependency TLV = Header ('HH') + Payload('IBBHI') # = 4 + 12 = 16 Bytes dependencies_num = len(dependencies[DEP_IMAGES_KEY]) protected_tlv_size += (dependencies_num * 16) if compression_tlvs is not None: for value in compression_tlvs.values(): protected_tlv_size += TLV_SIZE + len(value) if custom_tlvs is not None: for value in custom_tlvs.values(): protected_tlv_size += TLV_SIZE + len(value) if protected_tlv_size != 0: # Add the size of the TLV info header protected_tlv_size += TLV_INFO_SIZE # At this point the image is already on the payload # # This adds the padding if image is not aligned to the 16 Bytes # in encrypted mode if self.enckey is not None: pad_len = len(self.payload) % 16 if pad_len > 0: pad = bytes(16 - pad_len) if isinstance(self.payload, bytes): self.payload += pad else: self.payload.extend(pad) compression_flags = 0x0 if compression_tlvs is not None: if compression_type in ["lzma2", "lzma2armthumb"]: compression_flags = IMAGE_F['COMPRESSED_LZMA2'] if compression_type == "lzma2armthumb": compression_flags |= IMAGE_F['COMPRESSED_ARM_THUMB'] # This adds the header to the payload as well if encrypt_keylen == 256: self.add_header(enckey, protected_tlv_size, compression_flags, 256) else: self.add_header(enckey, protected_tlv_size, compression_flags) prot_tlv = TLV(self.endian, TLV_PROT_INFO_MAGIC) # Protected TLVs must be added first, because they are also included # in the hash calculation protected_tlv_off = None if protected_tlv_size != 0: e = STRUCT_ENDIAN_DICT[self.endian] if self.security_counter is not None: payload = struct.pack(e + 'I', self.security_counter) prot_tlv.add('SEC_CNT', payload) if sw_type is not None: prot_tlv.add('BOOT_RECORD', boot_record) if dependencies is not None: for i in range(dependencies_num): payload = struct.pack( e + 'B3x' + 'BBHI', int(dependencies[DEP_IMAGES_KEY][i]), dependencies[DEP_VERSIONS_KEY][i].major, dependencies[DEP_VERSIONS_KEY][i].minor, dependencies[DEP_VERSIONS_KEY][i].revision, dependencies[DEP_VERSIONS_KEY][i].build ) prot_tlv.add('DEPENDENCY', payload) if compression_tlvs is not None: for tag, value in compression_tlvs.items(): prot_tlv.add(tag, value) if custom_tlvs is not None: for tag, value in custom_tlvs.items(): prot_tlv.add(tag, value) protected_tlv_off = len(self.payload) self.payload += prot_tlv.get() tlv = TLV(self.endian) # These signature is done over sha of image. In case of # EC signatures so called Pure algorithm, designated to be run # over entire message is used with sha of image as message, # so, for example, in case of ED25519 we have here SHAxxx-ED25519-SHA512. sha = hash_algorithm() sha.update(self.payload) digest = sha.digest() tlv.add(hash_tlv, digest) # for external usage self.image_hash = digest # Unless pure, we are signing digest. message = digest if is_pure: # Note that when Pure signature is used, hash TLV is not present. message = bytes(self.payload) e = STRUCT_ENDIAN_DICT[self.endian] sig_pure = struct.pack(e + '?', True) tlv.add('SIG_PURE', sig_pure) if vector_to_sign == 'payload': # Stop amending data to the image # Just keep data vector which is expected to be signed print(os.path.basename(__file__) + ': export payload') return elif vector_to_sign == 'digest': self.payload = digest print(os.path.basename(__file__) + ': export digest') return if key is not None or fixed_sig is not None: if public_key_format == 'hash': tlv.add('KEYHASH', pubbytes) else: tlv.add('PUBKEY', pub) if key is not None and fixed_sig is None: # `sign` expects the full image payload (hashing done # internally), while `sign_digest` expects only the digest # of the payload if hasattr(key, 'sign'): print(os.path.basename(__file__) + ": sign the payload") sig = key.sign(bytes(self.payload)) else: print(os.path.basename(__file__) + ": sign the digest") sig = key.sign_digest(message) tlv.add(key.sig_tlv(), sig) self.signature = sig elif fixed_sig is not None and key is None: tlv.add(pub_key.sig_tlv(), fixed_sig['value']) self.signature = fixed_sig['value'] else: raise click.UsageError("Can not sign using key and provide fixed-signature at the same time") # At this point the image was hashed + signed, we can remove the # protected TLVs from the payload (will be re-added later) if protected_tlv_off is not None: self.payload = self.payload[:protected_tlv_off] if enckey is not None: if encrypt_keylen == 256: plainkey = os.urandom(32) else: plainkey = os.urandom(16) if isinstance(enckey, rsa.RSAPublic): cipherkey = enckey._get_public().encrypt( plainkey, padding.OAEP( mgf=padding.MGF1(algorithm=hashes.SHA256()), algorithm=hashes.SHA256(), label=None)) self.enctlv_len = len(cipherkey) tlv.add('ENCRSA2048', cipherkey) elif isinstance(enckey, (ecdsa.ECDSA256P1Public, x25519.X25519Public)): cipherkey, mac, pubk = self.ecies_hkdf(enckey, plainkey) enctlv = pubk + mac + cipherkey self.enctlv_len = len(enctlv) if isinstance(enckey, ecdsa.ECDSA256P1Public): tlv.add('ENCEC256', enctlv) else: tlv.add('ENCX25519', enctlv) if not clear: nonce = bytes([0] * 16) cipher = Cipher(algorithms.AES(plainkey), modes.CTR(nonce), backend=default_backend()) encryptor = cipher.encryptor() img = bytes(self.payload[self.header_size:]) self.payload[self.header_size:] = \ encryptor.update(img) + encryptor.finalize() self.payload += prot_tlv.get() self.payload += tlv.get() self.check_trailer() def get_struct_endian(self): return STRUCT_ENDIAN_DICT[self.endian] def get_signature(self): return self.signature def get_infile_data(self): return self.infile_data def add_header(self, enckey, protected_tlv_size, compression_flags, aes_length=128): """Install the image header.""" flags = 0 if enckey is not None: if aes_length == 128: flags |= IMAGE_F['ENCRYPTED_AES128'] else: flags |= IMAGE_F['ENCRYPTED_AES256'] if self.load_addr != 0: # Indicates that this image should be loaded into RAM # instead of run directly from flash. flags |= IMAGE_F['RAM_LOAD'] if self.rom_fixed: flags |= IMAGE_F['ROM_FIXED'] if self.non_bootable: flags |= IMAGE_F['NON_BOOTABLE'] e = STRUCT_ENDIAN_DICT[self.endian] fmt = (e + # type ImageHdr struct { 'I' + # Magic uint32 'I' + # LoadAddr uint32 'H' + # HdrSz uint16 'H' + # PTLVSz uint16 'I' + # ImgSz uint32 'I' + # Flags uint32 'BBHI' + # Vers ImageVersion 'I' # Pad1 uint32 ) # } assert struct.calcsize(fmt) == IMAGE_HEADER_SIZE header = struct.pack(fmt, IMAGE_MAGIC, self.rom_fixed or self.load_addr, self.header_size, protected_tlv_size, # TLV Info header + # Protected TLVs len(self.payload) - self.header_size, # ImageSz flags | compression_flags, self.version.major, self.version.minor or 0, self.version.revision or 0, self.version.build or 0, 0) # Pad1 self.payload = bytearray(self.payload) self.payload[:len(header)] = header def _trailer_size(self, write_size, max_sectors, overwrite_only, enckey, save_enctlv, enctlv_len): # NOTE: should already be checked by the argument parser magic_size = 16 magic_align_size = align_up(magic_size, self.max_align) if overwrite_only: return self.max_align * 2 + magic_align_size else: if write_size not in set([1, 2, 4, 8, 16, 32]): raise click.BadParameter("Invalid alignment: {}".format( write_size)) m = DEFAULT_MAX_SECTORS if max_sectors is None else max_sectors trailer = m * 3 * write_size # status area if enckey is not None: if save_enctlv: # TLV saved by the bootloader is aligned keylen = align_up(enctlv_len, self.max_align) else: keylen = align_up(16, self.max_align) trailer += keylen * 2 # encryption keys trailer += self.max_align * 4 # image_ok/copy_done/swap_info/swap_size trailer += magic_align_size return trailer def pad_to(self, size): """Pad the image to the given size, with the given flash alignment.""" tsize = self._trailer_size(self.align, self.max_sectors, self.overwrite_only, self.enckey, self.save_enctlv, self.enctlv_len) padding = size - (len(self.payload) + tsize) pbytes = bytearray([self.erased_val] * padding) pbytes += bytearray([self.erased_val] * (tsize - len(self.boot_magic))) pbytes += self.boot_magic if self.confirm and not self.overwrite_only: magic_size = 16 magic_align_size = align_up(magic_size, self.max_align) image_ok_idx = -(magic_align_size + self.max_align) pbytes[image_ok_idx] = 0x01 # image_ok = 0x01 self.payload += pbytes @staticmethod def verify(imgfile, key): ext = os.path.splitext(imgfile)[1][1:].lower() try: if ext == INTEL_HEX_EXT: b = IntelHex(imgfile).tobinstr() else: with open(imgfile, 'rb') as f: b = f.read() except FileNotFoundError: raise click.UsageError(f"Image file {imgfile} not found") magic, _, header_size, _, img_size = struct.unpack('IIHHI', b[:16]) version = struct.unpack('BBHI', b[20:28]) if magic != IMAGE_MAGIC: return VerifyResult.INVALID_MAGIC, None, None, None tlv_off = header_size + img_size tlv_info = b[tlv_off:tlv_off + TLV_INFO_SIZE] magic, tlv_tot = struct.unpack('HH', tlv_info) if magic == TLV_PROT_INFO_MAGIC: tlv_off += tlv_tot tlv_info = b[tlv_off:tlv_off + TLV_INFO_SIZE] magic, tlv_tot = struct.unpack('HH', tlv_info) if magic != TLV_INFO_MAGIC: return VerifyResult.INVALID_TLV_INFO_MAGIC, None, None, None # This is set by existence of TLV SIG_PURE is_pure = False prot_tlv_size = tlv_off hash_region = b[:prot_tlv_size] tlv_end = tlv_off + tlv_tot tlv_off += TLV_INFO_SIZE # skip tlv info # First scan all TLVs in search of SIG_PURE while tlv_off < tlv_end: tlv = b[tlv_off:tlv_off + TLV_SIZE] tlv_type, _, tlv_len = struct.unpack('BBH', tlv) if tlv_type == TLV_VALUES['SIG_PURE']: is_pure = True break tlv_off += TLV_SIZE + tlv_len digest = None tlv_off = header_size + img_size tlv_end = tlv_off + tlv_tot tlv_off += TLV_INFO_SIZE # skip tlv info while tlv_off < tlv_end: tlv = b[tlv_off:tlv_off + TLV_SIZE] tlv_type, _, tlv_len = struct.unpack('BBH', tlv) if is_sha_tlv(tlv_type): if not tlv_matches_key_type(tlv_type, key): return VerifyResult.KEY_MISMATCH, None, None, None off = tlv_off + TLV_SIZE digest = get_digest(tlv_type, hash_region) if digest == b[off:off + tlv_len]: if key is None: return VerifyResult.OK, version, digest, None else: return VerifyResult.INVALID_HASH, None, None, None elif not is_pure and key is not None and tlv_type == TLV_VALUES[key.sig_tlv()]: off = tlv_off + TLV_SIZE tlv_sig = b[off:off + tlv_len] payload = b[:prot_tlv_size] try: if hasattr(key, 'verify'): key.verify(tlv_sig, payload) else: key.verify_digest(tlv_sig, digest) return VerifyResult.OK, version, digest, None except InvalidSignature: # continue to next TLV pass elif is_pure and key is not None and tlv_type in ALLOWED_PURE_SIG_TLVS: off = tlv_off + TLV_SIZE tlv_sig = b[off:off + tlv_len] try: key.verify_digest(tlv_sig, hash_region) return VerifyResult.OK, version, None, tlv_sig except InvalidSignature: # continue to next TLV pass tlv_off += TLV_SIZE + tlv_len return VerifyResult.INVALID_SIGNATURE, None, None, None