refactor(python): convert firmware parsing to classes

poetry.lock

@@ -140,6 +140,17 @@ python-versions = ">=3.6"
 [package.extras]
 extras = ["arrow", "cloudpickle", "enum34", "lz4", "numpy", "ruamel.yaml"]
 
+[[package]]
+name = "construct-classes"
+version = "0.1.2"
+description = "Parse your binary structs into dataclasses"
+category = "main"
+optional = false
+python-versions = ">=3.6.2,<4.0"
+
+[package.dependencies]
+construct = ">=2.10,<3.0"
+
 [[package]]
 name = "coverage"
 version = "4.5.4"
@@ -569,8 +580,8 @@ python-versions = ">=3.6"
 importlib-metadata = {version = ">=0.12", markers = "python_version < \"3.8\""}
 
 [package.extras]
-dev = ["pre-commit", "tox"]
+testing = ["pytest-benchmark", "pytest"]
-testing = ["pytest", "pytest-benchmark"]
+dev = ["tox", "pre-commit"]
 
 [[package]]
 name = "protobuf"
@@ -835,8 +846,8 @@ click = ">=7,<9"
 colorama = "*"
 
 [package.extras]
-dev = ["black", "flake8", "isort"]
 tests = ["pytest"]
+dev = ["isort", "flake8", "black"]
 
 [[package]]
 name = "simple-rlp"
@@ -939,6 +950,7 @@ develop = true
 [package.dependencies]
 click = ">=7,<8.2"
 construct = ">=2.9,<2.10.55 || >2.10.55"
+construct-classes = ">=0.1.2"
 ecdsa = ">=0.9"
 libusb1 = ">=1.6.4"
 mnemonic = ">=0.20"
@@ -1067,7 +1079,31 @@ attrs = [
 autoflake = [
     {file = "autoflake-1.4.tar.gz", hash = "sha256:61a353012cff6ab94ca062823d1fb2f692c4acda51c76ff83a8d77915fba51ea"},
 ]
-black = []
+black = [
+    {file = "black-22.3.0-cp310-cp310-macosx_10_9_universal2.whl", hash = "sha256:2497f9c2386572e28921fa8bec7be3e51de6801f7459dffd6e62492531c47e09"},
+    {file = "black-22.3.0-cp310-cp310-macosx_10_9_x86_64.whl", hash = "sha256:5795a0375eb87bfe902e80e0c8cfaedf8af4d49694d69161e5bd3206c18618bb"},
+    {file = "black-22.3.0-cp310-cp310-macosx_11_0_arm64.whl", hash = "sha256:e3556168e2e5c49629f7b0f377070240bd5511e45e25a4497bb0073d9dda776a"},
+    {file = "black-22.3.0-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:67c8301ec94e3bcc8906740fe071391bce40a862b7be0b86fb5382beefecd968"},
+    {file = "black-22.3.0-cp310-cp310-win_amd64.whl", hash = "sha256:fd57160949179ec517d32ac2ac898b5f20d68ed1a9c977346efbac9c2f1e779d"},
+    {file = "black-22.3.0-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:cc1e1de68c8e5444e8f94c3670bb48a2beef0e91dddfd4fcc29595ebd90bb9ce"},
+    {file = "black-22.3.0-cp36-cp36m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:6d2fc92002d44746d3e7db7cf9313cf4452f43e9ea77a2c939defce3b10b5c82"},
+    {file = "black-22.3.0-cp36-cp36m-win_amd64.whl", hash = "sha256:a6342964b43a99dbc72f72812bf88cad8f0217ae9acb47c0d4f141a6416d2d7b"},
+    {file = "black-22.3.0-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:328efc0cc70ccb23429d6be184a15ce613f676bdfc85e5fe8ea2a9354b4e9015"},
+    {file = "black-22.3.0-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:06f9d8846f2340dfac80ceb20200ea5d1b3f181dd0556b47af4e8e0b24fa0a6b"},
+    {file = "black-22.3.0-cp37-cp37m-win_amd64.whl", hash = "sha256:ad4efa5fad66b903b4a5f96d91461d90b9507a812b3c5de657d544215bb7877a"},
+    {file = "black-22.3.0-cp38-cp38-macosx_10_9_universal2.whl", hash = "sha256:e8477ec6bbfe0312c128e74644ac8a02ca06bcdb8982d4ee06f209be28cdf163"},
+    {file = "black-22.3.0-cp38-cp38-macosx_10_9_x86_64.whl", hash = "sha256:637a4014c63fbf42a692d22b55d8ad6968a946b4a6ebc385c5505d9625b6a464"},
+    {file = "black-22.3.0-cp38-cp38-macosx_11_0_arm64.whl", hash = "sha256:863714200ada56cbc366dc9ae5291ceb936573155f8bf8e9de92aef51f3ad0f0"},
+    {file = "black-22.3.0-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:10dbe6e6d2988049b4655b2b739f98785a884d4d6b85bc35133a8fb9a2233176"},
+    {file = "black-22.3.0-cp38-cp38-win_amd64.whl", hash = "sha256:cee3e11161dde1b2a33a904b850b0899e0424cc331b7295f2a9698e79f9a69a0"},
+    {file = "black-22.3.0-cp39-cp39-macosx_10_9_universal2.whl", hash = "sha256:5891ef8abc06576985de8fa88e95ab70641de6c1fca97e2a15820a9b69e51b20"},
+    {file = "black-22.3.0-cp39-cp39-macosx_10_9_x86_64.whl", hash = "sha256:30d78ba6bf080eeaf0b7b875d924b15cd46fec5fd044ddfbad38c8ea9171043a"},
+    {file = "black-22.3.0-cp39-cp39-macosx_11_0_arm64.whl", hash = "sha256:ee8f1f7228cce7dffc2b464f07ce769f478968bfb3dd1254a4c2eeed84928aad"},
+    {file = "black-22.3.0-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:6ee227b696ca60dd1c507be80a6bc849a5a6ab57ac7352aad1ffec9e8b805f21"},
+    {file = "black-22.3.0-cp39-cp39-win_amd64.whl", hash = "sha256:9b542ced1ec0ceeff5b37d69838106a6348e60db7b8fdd245294dc1d26136265"},
+    {file = "black-22.3.0-py3-none-any.whl", hash = "sha256:bc58025940a896d7e5356952228b68f793cf5fcb342be703c3a2669a1488cb72"},
+    {file = "black-22.3.0.tar.gz", hash = "sha256:35020b8886c022ced9282b51b5a875b6d1ab0c387b31a065b84db7c33085ca79"},
+]
 certifi = [
     {file = "certifi-2021.10.8-py2.py3-none-any.whl", hash = "sha256:d62a0163eb4c2344ac042ab2bdf75399a71a2d8c7d47eac2e2ee91b9d6339569"},
     {file = "certifi-2021.10.8.tar.gz", hash = "sha256:78884e7c1d4b00ce3cea67b44566851c4343c120abd683433ce934a68ea58872"},
@@ -1142,6 +1178,10 @@ colorama = [
 construct = [
     {file = "construct-2.10.67.tar.gz", hash = "sha256:730235fedf4f2fee5cfadda1d14b83ef1bf23790fb1cc579073e10f70a050883"},
 ]
+construct-classes = [
+    {file = "construct-classes-0.1.2.tar.gz", hash = "sha256:72ac1abbae5bddb4918688713f991f5a7fb6c9b593646a82f4bf3ac53de7eeb5"},
+    {file = "construct_classes-0.1.2-py3-none-any.whl", hash = "sha256:e82437261790758bda41e45fb3d5622b54cfbf044ceb14774af68346faf5e08e"},
+]
 coverage = [
     {file = "coverage-4.5.4-cp26-cp26m-macosx_10_12_x86_64.whl", hash = "sha256:eee64c616adeff7db37cc37da4180a3a5b6177f5c46b187894e633f088fb5b28"},
     {file = "coverage-4.5.4-cp27-cp27m-macosx_10_12_x86_64.whl", hash = "sha256:ef824cad1f980d27f26166f86856efe11eff9912c4fed97d3804820d43fa550c"},
@@ -1219,7 +1259,10 @@ ecdsa = [
 ed25519 = [
     {file = "ed25519-1.5.tar.gz", hash = "sha256:02053ee019ceef0df97294be2d4d5a8fc120fc86e81e08bec1245fc0f9403358"},
 ]
-execnet = []
+execnet = [
+    {file = "execnet-1.9.0-py2.py3-none-any.whl", hash = "sha256:a295f7cc774947aac58dde7fdc85f4aa00c42adf5d8f5468fc630c1acf30a142"},
+    {file = "execnet-1.9.0.tar.gz", hash = "sha256:8f694f3ba9cc92cab508b152dcfe322153975c29bda272e2fd7f3f00f36e47c5"},
+]
 fido2 = [
     {file = "fido2-0.8.1.tar.gz", hash = "sha256:449068f6876f397c8bb96ebc6a75c81c2692f045126d3f13ece21d409acdf7c3"},
 ]
@@ -1562,7 +1605,10 @@ pytest = [
     {file = "pytest-6.2.5-py3-none-any.whl", hash = "sha256:7310f8d27bc79ced999e760ca304d69f6ba6c6649c0b60fb0e04a4a77cacc134"},
     {file = "pytest-6.2.5.tar.gz", hash = "sha256:131b36680866a76e6781d13f101efb86cf674ebb9762eb70d3082b6f29889e89"},
 ]
-pytest-forked = []
+pytest-forked = [
+    {file = "pytest-forked-1.4.0.tar.gz", hash = "sha256:8b67587c8f98cbbadfdd804539ed5455b6ed03802203485dd2f53c1422d7440e"},
+    {file = "pytest_forked-1.4.0-py3-none-any.whl", hash = "sha256:bbbb6717efc886b9d64537b41fb1497cfaf3c9601276be8da2cccfea5a3c8ad8"},
+]
 pytest-ordering = [
     {file = "pytest-ordering-0.6.tar.gz", hash = "sha256:561ad653626bb171da78e682f6d39ac33bb13b3e272d406cd555adb6b006bda6"},
     {file = "pytest_ordering-0.6-py2-none-any.whl", hash = "sha256:27fba3fc265f5d0f8597e7557885662c1bdc1969497cd58aff6ed21c3b617de2"},
@@ -1576,7 +1622,10 @@ pytest-timeout = [
     {file = "pytest-timeout-2.1.0.tar.gz", hash = "sha256:c07ca07404c612f8abbe22294b23c368e2e5104b521c1790195561f37e1ac3d9"},
     {file = "pytest_timeout-2.1.0-py3-none-any.whl", hash = "sha256:f6f50101443ce70ad325ceb4473c4255e9d74e3c7cd0ef827309dfa4c0d975c6"},
 ]
-pytest-xdist = []
+pytest-xdist = [
+    {file = "pytest-xdist-2.5.0.tar.gz", hash = "sha256:4580deca3ff04ddb2ac53eba39d76cb5dd5edeac050cb6fbc768b0dd712b4edf"},
+    {file = "pytest_xdist-2.5.0-py3-none-any.whl", hash = "sha256:6fe5c74fec98906deb8f2d2b616b5c782022744978e7bd4695d39c8f42d0ce65"},
+]
 python-bitcoinlib = [
     {file = "python-bitcoinlib-0.11.0.tar.gz", hash = "sha256:3daafd63cb755f6e2067b7c9c514053856034c9f9363c80c37007744d54a2e06"},
     {file = "python_bitcoinlib-0.11.0-py3-none-any.whl", hash = "sha256:6e7982734637135599e2136d3c88d622f147e3b29201636665f799365784cd9e"},
@@ -1589,6 +1638,13 @@ pyyaml = [
     {file = "PyYAML-6.0-cp310-cp310-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl", hash = "sha256:f84fbc98b019fef2ee9a1cb3ce93e3187a6df0b2538a651bfb890254ba9f90b5"},
     {file = "PyYAML-6.0-cp310-cp310-win32.whl", hash = "sha256:2cd5df3de48857ed0544b34e2d40e9fac445930039f3cfe4bcc592a1f836d513"},
     {file = "PyYAML-6.0-cp310-cp310-win_amd64.whl", hash = "sha256:daf496c58a8c52083df09b80c860005194014c3698698d1a57cbcfa182142a3a"},
+    {file = "PyYAML-6.0-cp311-cp311-macosx_10_9_x86_64.whl", hash = "sha256:d4b0ba9512519522b118090257be113b9468d804b19d63c71dbcf4a48fa32358"},
+    {file = "PyYAML-6.0-cp311-cp311-macosx_11_0_arm64.whl", hash = "sha256:81957921f441d50af23654aa6c5e5eaf9b06aba7f0a19c18a538dc7ef291c5a1"},
+    {file = "PyYAML-6.0-cp311-cp311-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:afa17f5bc4d1b10afd4466fd3a44dc0e245382deca5b3c353d8b757f9e3ecb8d"},
+    {file = "PyYAML-6.0-cp311-cp311-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:dbad0e9d368bb989f4515da330b88a057617d16b6a8245084f1b05400f24609f"},
+    {file = "PyYAML-6.0-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:432557aa2c09802be39460360ddffd48156e30721f5e8d917f01d31694216782"},
+    {file = "PyYAML-6.0-cp311-cp311-win32.whl", hash = "sha256:bfaef573a63ba8923503d27530362590ff4f576c626d86a9fed95822a8255fd7"},
+    {file = "PyYAML-6.0-cp311-cp311-win_amd64.whl", hash = "sha256:01b45c0191e6d66c470b6cf1b9531a771a83c1c4208272ead47a3ae4f2f603bf"},
     {file = "PyYAML-6.0-cp36-cp36m-macosx_10_9_x86_64.whl", hash = "sha256:897b80890765f037df3403d22bab41627ca8811ae55e9a722fd0392850ec4d86"},
     {file = "PyYAML-6.0-cp36-cp36m-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:50602afada6d6cbfad699b0c7bb50d5ccffa7e46a3d738092afddc1f9758427f"},
     {file = "PyYAML-6.0-cp36-cp36m-manylinux_2_17_s390x.manylinux2014_s390x.whl", hash = "sha256:48c346915c114f5fdb3ead70312bd042a953a8ce5c7106d5bfb1a5254e47da92"},

python/.changelog.d/2576.incompatible

@@ -0,0 +1 @@
+Refactored firmware parsing and validation to a more object oriented approach.

python/requirements.txt

@@ -7,3 +7,4 @@ construct>=2.9,!=2.10.55
 typing_extensions>=3.10
 dataclasses ; python_version<'3.7'
 simple-rlp>=0.1.2 ; python_version>='3.7'
+construct-classes>=0.1.2

python/src/trezorlib/_internal/firmware_headers.py

@@ -14,13 +14,15 @@
 # You should have received a copy of the License along with this library.
 # If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
 
-import struct
+import typing as t
+from copy import copy
+from dataclasses import asdict
 from enum import Enum
-from hashlib import blake2s
-from typing import Any, List, Optional
 
 import click
 import construct as c
+from construct_classes import Struct
+from typing_extensions import Protocol, Self, runtime_checkable
 
 from .. import cosi, firmware
 
@@ -43,48 +45,25 @@ VHASH_DEVEL = bytes.fromhex(
 )
 
 
-AnyFirmware = c.Struct(
-    "vendor_header" / c.Optional(firmware.VendorHeader),
-    "image" / c.Optional(firmware.FirmwareImage),
-)
-
-
 class ImageType(Enum):
     VENDOR_HEADER = 0
     BOOTLOADER = 1
     FIRMWARE = 2
 
 
-def _make_dev_keys(*key_bytes: bytes) -> List[bytes]:
+def _make_dev_keys(*key_bytes: bytes) -> t.Sequence[bytes]:
     return [k * 32 for k in key_bytes]
 
 
-def compute_vhash(vendor_header: c.Container) -> bytes:
-    m = vendor_header.sig_m
-    n = vendor_header.sig_n
-    pubkeys = vendor_header.pubkeys
-    h = blake2s()
-    h.update(struct.pack("<BB", m, n))
-    for i in range(8):
-        if i < n:
-            h.update(pubkeys[i])
-        else:
-            h.update(b"\x00" * 32)
-    return h.digest()
-
-
 def all_zero(data: bytes) -> bool:
     return all(b == 0 for b in data)
 
 
-def _check_signature_any(
+def _check_signature_any(fw: "SignableImageProto", is_devel: bool) -> Status:
-    header: c.Container, m: int, pubkeys: List[bytes], is_devel: bool
+    if not fw.signature_present():
-) -> Status:
-    if all_zero(header.signature) and header.sigmask == 0:
         return Status.MISSING
     try:
-        digest = firmware.header_digest(header)
+        fw.verify()
-        cosi.verify(header.signature, digest, m, pubkeys, header.sigmask)
         return Status.VALID if not is_devel else Status.DEVEL
     except Exception:
         return Status.INVALID
@@ -98,11 +77,11 @@ class LiteralStr(str):
 
 
 def _format_container(
-    pb: c.Container,
+    pb: t.Union[c.Container, Struct, dict],
     indent: int = 0,
     sep: str = " " * 4,
-    truncate_after: Optional[int] = 64,
+    truncate_after: t.Optional[int] = 64,
-    truncate_to: Optional[int] = 32,
+    truncate_to: t.Optional[int] = 32,
 ) -> str:
     def mostly_printable(bytes: bytes) -> bool:
         if not bytes:
@@ -110,7 +89,7 @@ def _format_container(
         printable = sum(1 for byte in bytes if 0x20 <= byte <= 0x7E)
         return printable / len(bytes) > 0.8
 
-    def pformat(value: Any, indent: int) -> str:
+    def pformat(value: t.Any, indent: int) -> str:
         level = sep * indent
         leadin = sep * (indent + 1)
 
@@ -127,6 +106,9 @@ def _format_container(
             lines[1:1] = [leadin + pformat(x, indent + 1) for x in value]
             return "\n".join(lines)
 
+        if isinstance(value, Struct):
+            value = asdict(value)
+
         if isinstance(value, dict):
             lines = ["{"]
             for key, val in value.items():
@@ -158,88 +140,140 @@ def _format_container(
     return pformat(pb, indent)
 
 
-def _format_version(version: c.Container) -> str:
+def _format_version(version: t.Tuple[int, ...]) -> str:
-    version_str = ".".join(
+    return ".".join(str(i) for i in version)
-        str(version[k]) for k in ("major", "minor", "patch") if k in version
+
-    )
+
-    if "build" in version:
+def format_header(
-        version_str += f" build {version.build}"
+    header: firmware.core.FirmwareHeader,
-    return version_str
+    code_hashes: t.Sequence[bytes],
+    digest: bytes,
+    sig_status: Status,
+) -> str:
+    header_dict = asdict(header)
+    header_out = header_dict.copy()
+
+    for key, val in header_out.items():
+        if "version" in key:
+            header_out[key] = LiteralStr(_format_version(val))
+
+    hashes_out = []
+    for expected, actual in zip(header.hashes, code_hashes):
+        status = SYM_OK if expected == actual else SYM_FAIL
+        hashes_out.append(LiteralStr(f"{status} {expected.hex()}"))
+
+    if all(all_zero(h) for h in header.hashes):
+        hash_status = Status.MISSING
+    elif header.hashes != code_hashes:
+        hash_status = Status.INVALID
+    else:
+        hash_status = Status.VALID
+
+    header_out["hashes"] = hashes_out
+
+    all_ok = SYM_OK if hash_status.is_ok() and sig_status.is_ok() else SYM_FAIL
+
+    output = [
+        "Firmware Header " + _format_container(header_out),
+        f"Fingerprint: {click.style(digest.hex(), bold=True)}",
+        f"{all_ok} Signature is {sig_status.value}, hashes are {hash_status.value}",
+    ]
+
+    return "\n".join(output)
 
 
 # =========================== functionality implementations ===============
 
 
-class SignableImage:
+class SignableImageProto(Protocol):
-    NAME = "Unrecognized image"
+    NAME: t.ClassVar[str]
-    BIP32_INDEX: Optional[int] = None
-    DEV_KEYS: List[bytes] = []
-    DEV_KEY_SIGMASK = 0b11
 
-    def __init__(self, fw: c.Container) -> None:
+    @classmethod
-        self.fw = fw
+    def parse(cls, data: bytes) -> Self:
-        self.header: Any
+        ...
-        self.public_keys: List[bytes]
-        self.sigs_required = firmware.V2_SIGS_REQUIRED
 
     def digest(self) -> bytes:
-        return firmware.header_digest(self.header)
+        ...
 
-    def check_signature(self) -> Status:
+    def verify(self) -> None:
-        raise NotImplementedError
+        ...
 
-    def rehash(self) -> None:
+    def build(self) -> bytes:
-        pass
+        ...
+
+    def format(self, verbose: bool = False) -> str:
+        ...
+
+    def signature_present(self) -> bool:
+        ...
+
+    def public_keys(self) -> t.Sequence[bytes]:
+        ...
+
+
+@runtime_checkable
+class CosiSignedImage(SignableImageProto, Protocol):
+    DEV_KEYS: t.ClassVar[t.Sequence[bytes]] = []
 
     def insert_signature(self, signature: bytes, sigmask: int) -> None:
-        self.header.signature = signature
+        ...
-        self.header.sigmask = sigmask
-
-    def dump(self) -> bytes:
-        return AnyFirmware.build(self.fw)
-
-    def format(self, verbose: bool) -> str:
-        return _format_container(self.fw)
 
 
-class VendorHeader(SignableImage):
+@runtime_checkable
+class LegacySignedImage(SignableImageProto, Protocol):
+    def slots(self) -> t.Iterable[int]:
+        ...
+
+    def insert_signature(self, slot: int, key_index: int, signature: bytes) -> None:
+        ...
+
+
+class CosiSignatureHeaderProto(Protocol):
+    signature: bytes
+    sigmask: int
+
+
+class CosiSignedMixin:
+    def signature_present(self) -> bool:
+        header = self.get_header()
+        return not all_zero(header.signature) or header.sigmask != 0
+
+    def insert_signature(self, signature: bytes, sigmask: int) -> None:
+        self.get_header().signature = signature
+        self.get_header().sigmask = sigmask
+
+    def get_header(self) -> CosiSignatureHeaderProto:
+        raise NotImplementedError
+
+
+class VendorHeader(firmware.VendorHeader, CosiSignedMixin):
     NAME = "vendorheader"
-    BIP32_INDEX = 1
     DEV_KEYS = _make_dev_keys(b"\x44", b"\x45")
 
-    def __init__(self, fw: c.Container) -> None:
+    SUBCON = c.Struct(*firmware.VendorHeader.SUBCON.subcons, c.Terminated)
-        super().__init__(fw)
-        self.header = fw.vendor_header
-        self.public_keys = firmware.V2_BOOTLOADER_KEYS
 
-    def check_signature(self) -> Status:
+    def get_header(self) -> CosiSignatureHeaderProto:
-        return _check_signature_any(
+        return self
-            self.header, self.sigs_required, self.public_keys, False
-        )
 
     def _format(self, terse: bool) -> str:
-        vh = self.fw.vendor_header
         if not terse:
-            vhash = compute_vhash(vh)
             output = [
-                "Vendor Header " + _format_container(vh),
+                "Vendor Header " + _format_container(self),
-                f"Pubkey bundle hash: {vhash.hex()}",
+                f"Pubkey bundle hash: {self.vhash().hex()}",
             ]
         else:
             output = [
                 "Vendor Header for {vendor} version {version} ({size} bytes)".format(
-                    vendor=click.style(vh.text, bold=True),
+                    vendor=click.style(self.text, bold=True),
-                    version=_format_version(vh.version),
+                    version=_format_version(self.version),
-                    size=vh.header_len,
+                    size=self.header_len,
                 ),
             ]
 
-        fingerprint = firmware.header_digest(vh)
-
         if not terse:
-            output.append(f"Fingerprint: {click.style(fingerprint.hex(), bold=True)}")
+            output.append(f"Fingerprint: {click.style(self.digest().hex(), bold=True)}")
 
-        sig_status = self.check_signature()
+        sig_status = _check_signature_any(self, is_devel=False)
         sym = SYM_OK if sig_status.is_ok() else SYM_FAIL
         output.append(f"{sym} Signature is {sig_status.value}")
 
@@ -248,138 +282,168 @@ class VendorHeader(SignableImage):
     def format(self, verbose: bool = False) -> str:
         return self._format(terse=False)
 
-
+    def public_keys(self) -> t.Sequence[bytes]:
-class BinImage(SignableImage):
+        return firmware.V2_BOOTLOADER_KEYS
-    def __init__(self, fw: c.Container) -> None:
-        super().__init__(fw)
-        self.header = self.fw.image.header
-        self.code_hashes = firmware.calculate_code_hashes(
-            self.fw.image.code, self.fw.image._code_offset
-        )
-        self.digest_header = self.header.copy()
-        self.digest_header.hashes = self.code_hashes
-
-    def insert_signature(self, signature: bytes, sigmask: int) -> None:
-        super().insert_signature(signature, sigmask)
-        self.digest_header.signature = signature
-        self.digest_header.sigmask = sigmask
-
-    def digest(self) -> bytes:
-        return firmware.header_digest(self.digest_header)
-
-    def rehash(self) -> None:
-        self.header.hashes = self.code_hashes
-
-    def format(self, verbose: bool = False) -> str:
-        header_out = self.header.copy()
-
-        if not verbose:
-            for key in self.header:
-                if key.startswith("v1"):
-                    del header_out[key]
-                if "version" in key:
-                    header_out[key] = LiteralStr(_format_version(self.header[key]))
-
-        all_ok = SYM_OK
-        hash_status = Status.VALID
-        sig_status = Status.VALID
-
-        hashes_out = []
-        for expected, actual in zip(self.header.hashes, self.code_hashes):
-            status = SYM_OK if expected == actual else SYM_FAIL
-            hashes_out.append(LiteralStr(f"{status} {expected.hex()}"))
-
-        if all(all_zero(h) for h in self.header.hashes):
-            hash_status = Status.MISSING
-        elif self.header.hashes != self.code_hashes:
-            hash_status = Status.INVALID
-        else:
-            hash_status = Status.VALID
-
-        header_out["hashes"] = hashes_out
-
-        sig_status = self.check_signature()
-        all_ok = SYM_OK if hash_status.is_ok() and sig_status.is_ok() else SYM_FAIL
-
-        output = [
-            "Firmware Header " + _format_container(header_out),
-            f"Fingerprint: {click.style(self.digest().hex(), bold=True)}",
-            f"{all_ok} Signature is {sig_status.value}, hashes are {hash_status.value}",
-        ]
-
-        return "\n".join(output)
 
 
-class FirmwareImage(BinImage):
+class VendorFirmware(firmware.VendorFirmware, CosiSignedMixin):
     NAME = "firmware"
-    BIP32_INDEX = 2
     DEV_KEYS = _make_dev_keys(b"\x47", b"\x48")
 
-    def __init__(self, fw: c.Container) -> None:
+    def get_header(self) -> CosiSignatureHeaderProto:
-        super().__init__(fw)
+        return self.firmware.header
-        self.public_keys = fw.vendor_header.pubkeys
-        self.sigs_required = fw.vendor_header.sig_m
-
-    def check_signature(self) -> Status:
-        vhash = compute_vhash(self.fw.vendor_header)
-        return _check_signature_any(
-            self.digest_header,
-            self.sigs_required,
-            self.public_keys,
-            vhash == VHASH_DEVEL,
-        )
 
     def format(self, verbose: bool = False) -> str:
+        vh = copy(self.vendor_header)
+        vh.__class__ = VendorHeader
+        assert isinstance(vh, VendorHeader)
+
+        is_devel = self.vendor_header.vhash() == VHASH_DEVEL
+
         return (
-            VendorHeader(self.fw)._format(terse=not verbose)
+            vh._format(terse=not verbose)
             + "\n"
-            + super().format(verbose)
+            + format_header(
+                self.firmware.header,
+                self.firmware.code_hashes(),
+                self.digest(),
+                _check_signature_any(self, is_devel),
+            )
         )
 
+    def public_keys(self) -> t.Sequence[bytes]:
+        return self.vendor_header.pubkeys
 
-class BootloaderImage(BinImage):
+
+class BootloaderImage(firmware.FirmwareImage, CosiSignedMixin):
     NAME = "bootloader"
-    BIP32_INDEX = 0
     DEV_KEYS = _make_dev_keys(b"\x41", b"\x42")
 
-    def __init__(self, fw: c.Container) -> None:
+    def get_header(self) -> CosiSignatureHeaderProto:
-        super().__init__(fw)
+        return self.header
-        self._identify_dev_keys()
 
-    def insert_signature(self, signature: bytes, sigmask: int) -> None:
+    def format(self, verbose: bool = False) -> str:
-        super().insert_signature(signature, sigmask)
+        return format_header(
-        self._identify_dev_keys()
-
-    def _identify_dev_keys(self) -> None:
-        # try checking signature with dev keys first
-        self.public_keys = firmware.V2_BOARDLOADER_DEV_KEYS
-        if not self.check_signature().is_ok():
-            # validation with dev keys failed, use production keys
-            self.public_keys = firmware.V2_BOARDLOADER_KEYS
-
-    def check_signature(self) -> Status:
-        return _check_signature_any(
             self.header,
-            self.sigs_required,
+            self.code_hashes(),
-            self.public_keys,
+            self.digest(),
-            self.public_keys == firmware.V2_BOARDLOADER_DEV_KEYS,
+            _check_signature_any(self, False),
         )
 
+    def verify(self) -> None:
+        self.validate_code_hashes()
+        try:
+            cosi.verify(
+                self.header.signature,
+                self.digest(),
+                firmware.V2_SIGS_REQUIRED,
+                firmware.V2_BOARDLOADER_KEYS,
+                self.header.sigmask,
+            )
+        except Exception:
+            raise firmware.InvalidSignatureError("Invalid bootloader signature")
 
-def parse_image(image: bytes) -> SignableImage:
+    def public_keys(self) -> t.Sequence[bytes]:
-    fw = AnyFirmware.parse(image)
+        return firmware.V2_BOARDLOADER_KEYS
-    if fw.vendor_header and not fw.image:
+
-        return VendorHeader(fw)
+
-    if (
+class LegacyFirmware(firmware.LegacyFirmware):
-        not fw.vendor_header
+    NAME = "legacy_firmware_v1"
-        and fw.image
+    BIP32_INDEX = None
-        and fw.image.header.magic == firmware.HeaderType.BOOTLOADER
+
-    ):
+    def signature_present(self) -> bool:
-        return BootloaderImage(fw)
+        return any(i != 0 for i in self.key_indexes) or any(
-    if (
+            not all_zero(sig) for sig in self.signatures
-        fw.vendor_header
+        )
-        and fw.image
+
-        and fw.image.header.magic == firmware.HeaderType.FIRMWARE
+    def insert_signature(self, slot: int, key_index: int, signature: bytes) -> None:
-    ):
+        if not 0 <= slot < firmware.V1_SIGNATURE_SLOTS:
-        return FirmwareImage(fw)
+            raise ValueError("Invalid slot number")
-    raise ValueError("Unrecognized image type")
+        if not 0 <= key_index < len(firmware.V1_BOOTLOADER_KEYS):
+            raise ValueError("Invalid key index")
+        self.key_indexes[slot] = key_index
+        self.signatures[slot] = signature
+
+    def format(self, verbose: bool = False) -> str:
+        contents = asdict(self).copy()
+        del contents["embedded_v2"]
+        if self.embedded_v2:
+            em = copy(self.embedded_v2)
+            em.__class__ = LegacyV2Firmware
+            assert isinstance(em, LegacyV2Firmware)
+            embedded_content = "\nEmbedded V2 header: " + em.format(verbose=verbose)
+        else:
+            embedded_content = ""
+
+        return _format_container(contents) + embedded_content
+
+    def public_keys(self) -> t.Sequence[bytes]:
+        return firmware.V1_BOOTLOADER_KEYS
+
+    def slots(self) -> t.Iterable[int]:
+        return self.key_indexes
+
+
+class LegacyV2Firmware(firmware.LegacyV2Firmware):
+    NAME = "legacy_firmware_v2"
+    BIP32_INDEX = 5
+
+    def signature_present(self) -> bool:
+        return any(i != 0 for i in self.header.v1_key_indexes) or any(
+            not all_zero(sig) for sig in self.header.v1_signatures
+        )
+
+    def insert_signature(self, slot: int, key_index: int, signature: bytes) -> None:
+        if not 0 <= slot < firmware.V1_SIGNATURE_SLOTS:
+            raise ValueError("Invalid slot number")
+        if not 0 <= key_index < len(firmware.V1_BOOTLOADER_KEYS):
+            raise ValueError("Invalid key index")
+        if not isinstance(self.header.v1_key_indexes, list):
+            self.header.v1_key_indexes = list(self.header.v1_key_indexes)
+        if not isinstance(self.header.v1_signatures, list):
+            self.header.v1_signatures = list(self.header.v1_signatures)
+        self.header.v1_key_indexes[slot] = key_index
+        self.header.v1_signatures[slot] = signature
+
+    def format(self, verbose: bool = False) -> str:
+        return format_header(
+            self.header,
+            self.code_hashes(),
+            self.digest(),
+            _check_signature_any(self, False),
+        )
+
+    def public_keys(self) -> t.Sequence[bytes]:
+        return firmware.V1_BOOTLOADER_KEYS
+
+    def slots(self) -> t.Iterable[int]:
+        return self.header.v1_key_indexes
+
+
+def parse_image(image: bytes) -> SignableImageProto:
+    try:
+        return VendorFirmware.parse(image)
+    except c.ConstructError:
+        pass
+
+    try:
+        return VendorHeader.parse(image)
+    except c.ConstructError:
+        pass
+
+    try:
+        firmware_img = firmware.core.FirmwareImage.parse(image)
+        if firmware_img.header.magic == firmware.core.HeaderType.BOOTLOADER:
+            return BootloaderImage.parse(image)
+        if firmware_img.header.magic == firmware.core.HeaderType.FIRMWARE:
+            return LegacyV2Firmware.parse(image)
+        raise ValueError("Unrecognized firmware header magic")
+    except c.ConstructError:
+        pass
+
+    try:
+        return LegacyFirmware.parse(image)
+    except c.ConstructError:
+        pass
+
+    raise ValueError("Unrecognized firmware type")

python/src/trezorlib/cli/firmware.py

@@ -26,19 +26,18 @@ from .. import exceptions, firmware
 from . import with_client
 
 if TYPE_CHECKING:
-    import construct as c
     from ..client import TrezorClient
     from . import TrezorConnection
 
 ALLOWED_FIRMWARE_FORMATS = {
-    1: (firmware.FirmwareFormat.TREZOR_ONE, firmware.FirmwareFormat.TREZOR_ONE_V2),
+    1: (firmware.LegacyFirmware, firmware.LegacyV2Firmware),
-    2: (firmware.FirmwareFormat.TREZOR_T,),
+    2: (firmware.VendorFirmware,),
 }
 
 
-def _print_version(version: dict) -> None:
+def _print_version(version: Tuple[int, int, int, int]) -> None:
-    vstr = "Firmware version {major}.{minor}.{patch} build {build}".format(**version)
+    major, minor, patch, build = version
-    click.echo(vstr)
+    click.echo(f"Firmware version {major}.{minor}.{patch} build {build}")
 
 
 def _is_bootloader_onev2(client: "TrezorClient") -> bool:
@@ -59,32 +58,26 @@ def _get_file_name_from_url(url: str) -> str:
     return os.path.basename(full_path)
 
 
-def print_firmware_version(
+def print_firmware_version(fw: "firmware.FirmwareType") -> None:
-    version: firmware.FirmwareFormat,
-    fw: "c.Container",
-) -> None:
     """Print out the firmware version and details."""
-    if version == firmware.FirmwareFormat.TREZOR_ONE:
+    if isinstance(fw, firmware.LegacyFirmware):
-        if fw.embedded_onev2:
+        if fw.embedded_v2:
             click.echo("Trezor One firmware with embedded v2 image (1.8.0 or later)")
-            _print_version(fw.embedded_onev2.header.version)
+            _print_version(fw.embedded_v2.header.version)
         else:
             click.echo("Trezor One firmware image.")
-    elif version == firmware.FirmwareFormat.TREZOR_ONE_V2:
+    elif isinstance(fw, firmware.LegacyV2Firmware):
         click.echo("Trezor One v2 firmware (1.8.0 or later)")
         _print_version(fw.header.version)
-    elif version == firmware.FirmwareFormat.TREZOR_T:
+    elif isinstance(fw, firmware.VendorFirmware):
         click.echo("Trezor T firmware image.")
         vendor = fw.vendor_header.text
-        vendor_version = "{major}.{minor}".format(**fw.vendor_header.version)
+        vendor_version = "{}.{}".format(*fw.vendor_header.version)
         click.echo(f"Vendor header from {vendor}, version {vendor_version}")
-        _print_version(fw.image.header.version)
+        _print_version(fw.firmware.header.version)
 
 
-def validate_signatures(
+def validate_signatures(fw: "firmware.FirmwareType") -> None:
-    version: firmware.FirmwareFormat,
-    fw: "c.Container",
-) -> None:
     """Check the signatures on the firmware.
 
     Prints the validity status.
@@ -92,18 +85,25 @@ def validate_signatures(
     Exits if the validation fails.
     """
     try:
-        firmware.validate(version, fw, allow_unsigned=False)
+        fw.verify()
         click.echo("Signatures are valid.")
     except firmware.Unsigned:
+        if not isinstance(fw, firmware.LegacyFirmware):
+            raise
+
+        # allow legacy firmware without signatures
         if not click.confirm("No signatures found. Continue?", default=False):
             sys.exit(1)
+        if firmware.is_onev2(fw):
             try:
-            firmware.validate(version, fw, allow_unsigned=True)
+                assert fw.embedded_v2 is not None
-            click.echo("Unsigned firmware looking OK.")
+                fw.embedded_v2.verify_unsigned()
             except firmware.FirmwareIntegrityError as e:
                 click.echo(e)
                 click.echo("Firmware validation failed, aborting.")
                 sys.exit(4)
+        click.echo("Unsigned firmware looking OK.")
+
     except firmware.FirmwareIntegrityError as e:
         click.echo(e)
         click.echo("Firmware validation failed, aborting.")
@@ -111,8 +111,7 @@ def validate_signatures(
 
 
 def validate_fingerprint(
-    version: firmware.FirmwareFormat,
+    fw: "firmware.FirmwareType",
-    fw: "c.Container",
     expected_fingerprint: Optional[str] = None,
 ) -> None:
     """Determine and validate the firmware fingerprint.
@@ -120,12 +119,11 @@ def validate_fingerprint(
     Prints the fingerprint.
     Exits if the validation fails.
     """
-    fingerprint = firmware.digest(version, fw).hex()
+    fingerprint = fw.digest().hex()
     click.echo(f"Firmware fingerprint: {fingerprint}")
-    if version == firmware.FirmwareFormat.TREZOR_ONE and fw.embedded_onev2:
+    if firmware.is_onev2(fw):
-        fingerprint_onev2 = firmware.digest(
+        assert fw.embedded_v2 is not None
-            firmware.FirmwareFormat.TREZOR_ONE_V2, fw.embedded_onev2
+        fingerprint_onev2 = fw.embedded_v2.digest().hex()
-        ).hex()
         click.echo(f"Embedded v2 image fingerprint: {fingerprint_onev2}")
     if expected_fingerprint and fingerprint != expected_fingerprint:
         click.echo(f"Expected fingerprint: {expected_fingerprint}")
@@ -134,8 +132,7 @@ def validate_fingerprint(
 
 
 def check_device_match(
-    version: firmware.FirmwareFormat,
+    fw: "firmware.FirmwareType",
-    fw: "c.Container",
     bootloader_onev2: bool,
     trezor_major_version: int,
 ) -> None:
@@ -143,24 +140,24 @@ def check_device_match(
 
     Prints error message and exits if the validation fails.
     """
-    if (
-        bootloader_onev2
-        and version == firmware.FirmwareFormat.TREZOR_ONE
-        and not fw.embedded_onev2
-    ):
-        click.echo("Firmware is too old for your device. Aborting.")
-        sys.exit(3)
-    elif not bootloader_onev2 and version == firmware.FirmwareFormat.TREZOR_ONE_V2:
-        click.echo("You need to upgrade to bootloader 1.8.0 first.")
-        sys.exit(3)
-
     if trezor_major_version not in ALLOWED_FIRMWARE_FORMATS:
         click.echo("trezorctl doesn't know your device version. Aborting.")
         sys.exit(3)
-    elif version not in ALLOWED_FIRMWARE_FORMATS[trezor_major_version]:
+    elif not isinstance(fw, ALLOWED_FIRMWARE_FORMATS[trezor_major_version]):
         click.echo("Firmware does not match your device, aborting.")
         sys.exit(3)
 
+    if (
+        bootloader_onev2
+        and isinstance(fw, firmware.LegacyFirmware)
+        and not fw.embedded_v2
+    ):
+        click.echo("Firmware is too old for your device. Aborting.")
+        sys.exit(3)
+    elif not bootloader_onev2 and isinstance(fw, firmware.LegacyV2Firmware):
+        click.echo("You need to upgrade to bootloader 1.8.0 first.")
+        sys.exit(3)
+
 
 def get_all_firmware_releases(
     bitcoin_only: bool, beta: bool, major_version: int
@@ -348,18 +345,17 @@ def validate_firmware(
     - being compatible with the device (when chosen)
     """
     try:
-        version, fw = firmware.parse(firmware_data)
+        fw = firmware.parse(firmware_data)
     except Exception as e:
         click.echo(e)
         sys.exit(2)
 
-    print_firmware_version(version, fw)
+    print_firmware_version(fw)
-    validate_signatures(version, fw)
+    validate_signatures(fw)
-    validate_fingerprint(version, fw, fingerprint)
+    validate_fingerprint(fw, fingerprint)
 
     if bootloader_onev2 is not None and trezor_major_version is not None:
         check_device_match(
-            version=version,
             fw=fw,
             bootloader_onev2=bootloader_onev2,
             trezor_major_version=trezor_major_version,
@@ -372,7 +368,7 @@ def extract_embedded_fw(
     bootloader_onev2: bool,
 ) -> bytes:
     """Modify the firmware data for sending into Trezor, if necessary."""
-    # special handling for embedded-OneV2 format:
+    # special handling for embedded_v2-OneV2 format:
     # for bootloader < 1.8, keep the embedding
     # for bootloader 1.8.0 and up, strip the old OneV1 header
     if (
@@ -380,7 +376,7 @@ def extract_embedded_fw(
         and firmware_data[:4] == b"TRZR"
         and firmware_data[256 : 256 + 4] == b"TRZF"
     ):
-        click.echo("Extracting embedded firmware image.")
+        click.echo("Extracting embedded_v2 firmware image.")
         return firmware_data[256:]
 
     return firmware_data

python/src/trezorlib/cosi.py

@@ -16,7 +16,7 @@
 
 import warnings
 from functools import reduce
-from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
+from typing import TYPE_CHECKING, Iterable, Optional, Sequence, Tuple
 
 from . import _ed25519, messages
 from .tools import expect
@@ -90,7 +90,7 @@ def verify(
     signature: Ed25519Signature,
     digest: bytes,
     sigs_required: int,
-    keys: List[Ed25519PublicPoint],
+    keys: Sequence[Ed25519PublicPoint],
     mask: int,
 ) -> None:
     """Verify a CoSi multi-signature. Raise exception if the signature is invalid.

python/src/trezorlib/firmware/__init__.py

@@ -14,443 +14,62 @@
 # You should have received a copy of the License along with this library.
 # If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
 
-import hashlib
+import typing as t
-from enum import Enum
 from hashlib import blake2s
-from typing import TYPE_CHECKING, Any, Callable, List, Optional, Tuple
 
-import construct as c
+from typing_extensions import Protocol, TypeGuard
-import ecdsa
 
-from . import cosi, messages
+from .. import messages
-from .toif import ToifStruct
+from ..tools import expect, session
-from .tools import expect, session, EnumAdapter
+from .core import VendorFirmware
+from .legacy import LegacyFirmware, LegacyV2Firmware
 
-if TYPE_CHECKING:
+# re-exports:
-    from .client import TrezorClient
+if True:
-
+    # indented block prevents isort from messing with these until we upgrade to 5.x
-V1_SIGNATURE_SLOTS = 3
+    from .consts import *  # noqa: F401, F403
-V1_BOOTLOADER_KEYS = [
+    from .core import *  # noqa: F401, F403
-    bytes.fromhex(key)
+    from .legacy import *  # noqa: F401, F403
-    for key in (
+    from .util import (  # noqa: F401
-        "04d571b7f148c5e4232c3814f777d8faeaf1a84216c78d569b71041ffc768a5b2d810fc3bb134dd026b57e65005275aedef43e155f48fc11a32ec790a93312bd58",
+        FirmwareIntegrityError,
-        "0463279c0c0866e50c05c799d32bd6bab0188b6de06536d1109d2ed9ce76cb335c490e55aee10cc901215132e853097d5432eda06b792073bd7740c94ce4516cb1",
+        InvalidSignatureError,
-        "0443aedbb6f7e71c563f8ed2ef64ec9981482519e7ef4f4aa98b27854e8c49126d4956d300ab45fdc34cd26bc8710de0a31dbdf6de7435fd0b492be70ac75fde58",
+        Unsigned,
-        "04877c39fd7c62237e038235e9c075dab261630f78eeb8edb92487159fffedfdf6046c6f8b881fa407c4a4ce6c28de0b19c1f4e29f1fcbc5a58ffd1432a3e0938a",
-        "047384c51ae81add0a523adbb186c91b906ffb64c2c765802bf26dbd13bdf12c319e80c2213a136c8ee03d7874fd22b70d68e7dee469decfbbb510ee9a460cda45",
     )
-]
+    from .vendor import *  # noqa: F401, F403
 
-V2_BOARDLOADER_KEYS = [
+if t.TYPE_CHECKING:
-    bytes.fromhex(key)
+    from ..client import TrezorClient
-    for key in (
-        "0eb9856be9ba7e972c7f34eac1ed9b6fd0efd172ec00faf0c589759da4ddfba0",
-        "ac8ab40b32c98655798fd5da5e192be27a22306ea05c6d277cdff4a3f4125cd8",
-        "ce0fcd12543ef5936cf2804982136707863d17295faced72af171d6e6513ff06",
-    )
-]
 
-V2_BOARDLOADER_DEV_KEYS = [
+    T = t.TypeVar("T", bound="FirmwareType")
-    bytes.fromhex(key)
-    for key in (
-        "db995fe25169d141cab9bbba92baa01f9f2e1ece7df4cb2ac05190f37fcc1f9d",
-        "2152f8d19b791d24453242e15f2eab6cb7cffa7b6a5ed30097960e069881db12",
-        "22fc297792f0b6ffc0bfcfdb7edb0c0aa14e025a365ec0e342e86e3829cb74b6",
-    )
-]
 
-V2_BOOTLOADER_KEYS = [
+    class FirmwareType(Protocol):
-    bytes.fromhex(key)
+        @classmethod
-    for key in (
+        def parse(cls: t.Type[T], data: bytes) -> T:
-        "c2c87a49c5a3460977fbb2ec9dfe60f06bd694db8244bd4981fe3b7a26307f3f",
+            ...
-        "80d036b08739b846f4cb77593078deb25dc9487aedcf52e30b4fb7cd7024178a",
-        "b8307a71f552c60a4cbb317ff48b82cdbf6b6bb5f04c920fec7badf017883751",
-    )
-]
 
-V2_SIGS_REQUIRED = 2
+        def verify(self, public_keys: t.Sequence[bytes] = ()) -> None:
+            ...
 
-ONEV2_CHUNK_SIZE = 1024 * 64
+        def digest(self) -> bytes:
-V2_CHUNK_SIZE = 1024 * 128
+            ...
 
 
-def _transform_vendor_trust(data: bytes) -> bytes:
+def parse(data: bytes) -> "FirmwareType":
-    """Byte-swap and bit-invert the VendorTrust field.
+    try:
-
-    Vendor trust is interpreted as a bitmask in a 16-bit little-endian integer,
-    with the added twist that 0 means set and 1 means unset.
-    We feed it to a `BitStruct` that expects a big-endian sequence where bits have
-    the traditional meaning. We must therefore do a bitwise negation of each byte,
-    and return them in reverse order. This is the same transformation both ways,
-    fortunately, so we don't need two separate functions.
-    """
-    return bytes(~b & 0xFF for b in data)[::-1]
-
-
-class FirmwareIntegrityError(Exception):
-    pass
-
-
-class InvalidSignatureError(FirmwareIntegrityError):
-    pass
-
-
-class Unsigned(FirmwareIntegrityError):
-    pass
-
-
-class HeaderType(Enum):
-    FIRMWARE = b"TRZF"
-    BOOTLOADER = b"TRZB"
-
-
-# fmt: off
-VendorTrust = c.Transformed(c.BitStruct(
-    "_reserved" / c.Default(c.BitsInteger(9), 0),
-    "show_vendor_string" / c.Flag,
-    "require_user_click" / c.Flag,
-    "red_background" / c.Flag,
-    "delay" / c.BitsInteger(4),
-), _transform_vendor_trust, 2, _transform_vendor_trust, 2)
-
-
-VendorHeader = c.Struct(
-    "_start_offset" / c.Tell,
-    "magic" / c.Const(b"TRZV"),
-    "header_len" / c.Int32ul,
-    "expiry" / c.Int32ul,
-    "version" / c.Struct(
-        "major" / c.Int8ul,
-        "minor" / c.Int8ul,
-    ),
-    "sig_m" / c.Int8ul,
-    "sig_n" / c.Rebuild(c.Int8ul, c.len_(c.this.pubkeys)),
-    "trust" / VendorTrust,
-    "_reserved" / c.Padding(14),
-    "pubkeys" / c.Bytes(32)[c.this.sig_n],
-    "text" / c.Aligned(4, c.PascalString(c.Int8ul, "utf-8")),
-    "image" / ToifStruct,
-    "_end_offset" / c.Tell,
-
-    "_min_header_len" / c.Check(c.this.header_len > (c.this._end_offset - c.this._start_offset) + 65),
-    "_header_len_aligned" / c.Check(c.this.header_len % 512 == 0),
-
-    c.Padding(c.this.header_len - c.this._end_offset + c.this._start_offset - 65),
-    "sigmask" / c.Byte,
-    "signature" / c.Bytes(64),
-)
-
-
-VersionLong = c.Struct(
-    "major" / c.Int8ul,
-    "minor" / c.Int8ul,
-    "patch" / c.Int8ul,
-    "build" / c.Int8ul,
-)
-
-
-FirmwareHeader = c.Struct(
-    "_start_offset" / c.Tell,
-    "magic" / EnumAdapter(c.Bytes(4), HeaderType),
-    "header_len" / c.Int32ul,
-    "expiry" / c.Int32ul,
-    "code_length" / c.Rebuild(
-        c.Int32ul,
-        lambda this:
-            len(this._.code) if "code" in this._
-            else (this.code_length or 0)
-    ),
-    "version" / VersionLong,
-    "fix_version" / VersionLong,
-    "_reserved" / c.Padding(8),
-    "hashes" / c.Bytes(32)[16],
-
-    "v1_signatures" / c.Bytes(64)[V1_SIGNATURE_SLOTS],
-    "v1_key_indexes" / c.Int8ul[V1_SIGNATURE_SLOTS],  # pylint: disable=E1136
-
-    "_reserved" / c.Padding(220),
-    "sigmask" / c.Byte,
-    "signature" / c.Bytes(64),
-
-    "_end_offset" / c.Tell,
-
-    "_rebuild_header_len" / c.If(
-        c.this.version.major > 1,
-        c.Pointer(
-            c.this._start_offset + 4,
-            c.Rebuild(c.Int32ul, c.this._end_offset - c.this._start_offset)
-        ),
-    ),
-)
-
-
-"""Raw firmware image.
-
-Consists of firmware header and code block.
-This is the expected format of firmware binaries for Trezor One, or bootloader images
-for Trezor T."""
-FirmwareImage = c.Struct(
-    "header" / FirmwareHeader,
-    "_code_offset" / c.Tell,
-    "code" / c.Bytes(c.this.header.code_length),
-    c.Terminated,
-)
-
-
-"""Firmware image prefixed by a vendor header.
-
-This is the expected format of firmware binaries for Trezor T."""
-VendorFirmware = c.Struct(
-    "vendor_header" / VendorHeader,
-    "image" / FirmwareImage,
-    c.Terminated,
-)
-
-
-"""Legacy firmware image.
-Consists of a custom header and code block.
-This is the expected format of firmware binaries for Trezor One pre-1.8.0.
-
-The code block can optionally be interpreted as a new-style firmware image. That is the
-expected format of firmware binary for Trezor One version 1.8.0, which can be installed
-by both the older and the newer bootloader."""
-LegacyFirmware = c.Struct(
-    "magic" / c.Const(b"TRZR"),
-    "code_length" / c.Rebuild(c.Int32ul, c.len_(c.this.code)),
-    "key_indexes" / c.Int8ul[V1_SIGNATURE_SLOTS],  # pylint: disable=E1136
-    "flags" / c.BitStruct(
-        c.Padding(7),
-        "restore_storage" / c.Flag,
-    ),
-    "_reserved" / c.Padding(52),
-    "signatures" / c.Bytes(64)[V1_SIGNATURE_SLOTS],
-    "code" / c.Bytes(c.this.code_length),
-    c.Terminated,
-
-    "embedded_onev2" / c.RestreamData(c.this.code, c.Optional(FirmwareImage)),
-)
-
-# fmt: on
-
-
-class FirmwareFormat(Enum):
-    TREZOR_ONE = 1
-    TREZOR_T = 2
-    TREZOR_ONE_V2 = 3
-
-
-ParsedFirmware = Tuple[FirmwareFormat, c.Container]
-
-
-def parse(data: bytes) -> ParsedFirmware:
         if data[:4] == b"TRZR":
-        version = FirmwareFormat.TREZOR_ONE
+            return LegacyFirmware.parse(data)
-        cls = LegacyFirmware
         elif data[:4] == b"TRZV":
-        version = FirmwareFormat.TREZOR_T
+            return VendorFirmware.parse(data)
-        cls = VendorFirmware
         elif data[:4] == b"TRZF":
-        version = FirmwareFormat.TREZOR_ONE_V2
+            return LegacyV2Firmware.parse(data)
-        cls = FirmwareImage
         else:
             raise ValueError("Unrecognized firmware image type")
-
-    try:
-        fw = cls.parse(data)
     except Exception as e:
         raise FirmwareIntegrityError("Invalid firmware image") from e
-    return version, fw
 
 
-def digest_onev1(fw: c.Container) -> bytes:
+def is_onev2(fw: "FirmwareType") -> TypeGuard[LegacyFirmware]:
-    return hashlib.sha256(fw.code).digest()
+    return isinstance(fw, LegacyFirmware) and fw.embedded_v2 is not None
-
-
-def check_sig_v1(
-    digest: bytes, key_indexes: List[int], signatures: List[bytes]
-) -> None:
-    distinct_key_indexes = set(i for i in key_indexes if i != 0)
-    if not distinct_key_indexes:
-        raise Unsigned
-
-    if len(distinct_key_indexes) < len(key_indexes):
-        raise InvalidSignatureError(
-            f"Not enough distinct signatures (found {len(distinct_key_indexes)}, need {len(key_indexes)})"
-        )
-
-    for i in range(len(key_indexes)):
-        key_idx = key_indexes[i] - 1
-        signature = signatures[i]
-
-        if key_idx >= len(V1_BOOTLOADER_KEYS):
-            # unknown pubkey
-            raise InvalidSignatureError(f"Unknown key in slot {i}")
-
-        pubkey = V1_BOOTLOADER_KEYS[key_idx][1:]
-        verify = ecdsa.VerifyingKey.from_string(pubkey, curve=ecdsa.curves.SECP256k1)
-        try:
-            verify.verify_digest(signature, digest)
-        except ecdsa.BadSignatureError as e:
-            raise InvalidSignatureError(f"Invalid signature in slot {i}") from e
-
-
-def header_digest(header: c.Container, hash_function: Callable = blake2s) -> bytes:
-    stripped_header = header.copy()
-    stripped_header.sigmask = 0
-    stripped_header.signature = b"\0" * 64
-    stripped_header.v1_key_indexes = [0, 0, 0]
-    stripped_header.v1_signatures = [b"\0" * 64] * 3
-    if header.magic == b"TRZV":
-        header_type = VendorHeader
-    else:
-        header_type = FirmwareHeader
-    header_bytes = header_type.build(stripped_header)
-    return hash_function(header_bytes).digest()
-
-
-def digest_v2(fw: c.Container) -> bytes:
-    return header_digest(fw.image.header, blake2s)
-
-
-def digest_onev2(fw: c.Container) -> bytes:
-    return header_digest(fw.header, hashlib.sha256)
-
-
-def calculate_code_hashes(
-    code: bytes,
-    code_offset: int,
-    hash_function: Callable = blake2s,
-    chunk_size: int = V2_CHUNK_SIZE,
-    padding_byte: Optional[bytes] = None,
-) -> List[bytes]:
-    hashes = []
-    # End offset for each chunk. Normally this would be (i+1)*chunk_size for i-th chunk,
-    # but the first chunk is shorter by code_offset, so all end offsets are shifted.
-    ends = [(i + 1) * chunk_size - code_offset for i in range(16)]
-    start = 0
-    for end in ends:
-        chunk = code[start:end]
-        # padding for last non-empty chunk
-        if padding_byte is not None and start < len(code) and end > len(code):
-            chunk += padding_byte[0:1] * (end - start - len(chunk))
-
-        if not chunk:
-            hashes.append(b"\0" * 32)
-        else:
-            hashes.append(hash_function(chunk).digest())
-
-        start = end
-
-    return hashes
-
-
-def validate_code_hashes(fw: c.Container, version: FirmwareFormat) -> None:
-    hash_function: Callable
-    padding_byte: Optional[bytes]
-    if version == FirmwareFormat.TREZOR_ONE_V2:
-        image = fw
-        hash_function = hashlib.sha256
-        chunk_size = ONEV2_CHUNK_SIZE
-        padding_byte = b"\xff"
-    else:
-        image = fw.image
-        hash_function = blake2s
-        chunk_size = V2_CHUNK_SIZE
-        padding_byte = None
-
-    expected_hashes = calculate_code_hashes(
-        image.code, image._code_offset, hash_function, chunk_size, padding_byte
-    )
-    if expected_hashes != image.header.hashes:
-        raise FirmwareIntegrityError("Invalid firmware data.")
-
-
-def validate_onev2(fw: c.Container, allow_unsigned: bool = False) -> None:
-    try:
-        check_sig_v1(
-            digest_onev2(fw),
-            fw.header.v1_key_indexes,
-            fw.header.v1_signatures,
-        )
-    except Unsigned:
-        if not allow_unsigned:
-            raise
-
-    validate_code_hashes(fw, FirmwareFormat.TREZOR_ONE_V2)
-
-
-def validate_onev1(fw: c.Container, allow_unsigned: bool = False) -> None:
-    try:
-        check_sig_v1(digest_onev1(fw), fw.key_indexes, fw.signatures)
-    except Unsigned:
-        if not allow_unsigned:
-            raise
-    if fw.embedded_onev2:
-        validate_onev2(fw.embedded_onev2, allow_unsigned)
-
-
-def validate_v2(fw: c.Container, skip_vendor_header: bool = False) -> None:
-    vendor_fingerprint = header_digest(fw.vendor_header)
-    fingerprint = digest_v2(fw)
-
-    if not skip_vendor_header:
-        try:
-            # if you want to validate a custom vendor header, you can modify
-            # the global variables to match your keys and m-of-n scheme
-            cosi.verify(
-                fw.vendor_header.signature,
-                vendor_fingerprint,
-                V2_SIGS_REQUIRED,
-                V2_BOOTLOADER_KEYS,
-                fw.vendor_header.sigmask,
-            )
-        except Exception:
-            raise InvalidSignatureError("Invalid vendor header signature.")
-
-        # XXX expiry is not used now
-        # now = time.gmtime()
-        # if time.gmtime(fw.vendor_header.expiry) < now:
-        #     raise ValueError("Vendor header expired.")
-
-    try:
-        cosi.verify(
-            fw.image.header.signature,
-            fingerprint,
-            fw.vendor_header.sig_m,
-            fw.vendor_header.pubkeys,
-            fw.image.header.sigmask,
-        )
-    except Exception:
-        raise InvalidSignatureError("Invalid firmware signature.")
-
-    # XXX expiry is not used now
-    # if time.gmtime(fw.image.header.expiry) < now:
-    #     raise ValueError("Firmware header expired.")
-    validate_code_hashes(fw, FirmwareFormat.TREZOR_T)
-
-
-def digest(version: FirmwareFormat, fw: c.Container) -> bytes:
-    if version == FirmwareFormat.TREZOR_ONE:
-        return digest_onev1(fw)
-    elif version == FirmwareFormat.TREZOR_ONE_V2:
-        return digest_onev2(fw)
-    elif version == FirmwareFormat.TREZOR_T:
-        return digest_v2(fw)
-    else:
-        raise ValueError("Unrecognized firmware version")
-
-
-def validate(
-    version: FirmwareFormat, fw: c.Container, allow_unsigned: bool = False
-) -> None:
-    if version == FirmwareFormat.TREZOR_ONE:
-        return validate_onev1(fw, allow_unsigned)
-    elif version == FirmwareFormat.TREZOR_ONE_V2:
-        return validate_onev2(fw, allow_unsigned)
-    elif version == FirmwareFormat.TREZOR_T:
-        return validate_v2(fw)
-    else:
-        raise ValueError("Unrecognized firmware version")
 
 
 # ====== Client functions ====== #
@@ -460,7 +79,7 @@ def validate(
 def update(
     client: "TrezorClient",
     data: bytes,
-    progress_update: Callable[[int], Any] = lambda _: None,
+    progress_update: t.Callable[[int], t.Any] = lambda _: None,
 ):
     if client.features.bootloader_mode is False:
         raise RuntimeError("Device must be in bootloader mode")
@@ -493,5 +112,5 @@ def update(
 
 
 @expect(messages.FirmwareHash, field="hash", ret_type=bytes)
-def get_hash(client: "TrezorClient", challenge: Optional[bytes]):
+def get_hash(client: "TrezorClient", challenge: t.Optional[bytes]):
     return client.call(messages.GetFirmwareHash(challenge=challenge))

python/src/trezorlib/firmware/consts.py

@@ -0,0 +1,43 @@
+V1_SIGNATURE_SLOTS = 3
+V1_BOOTLOADER_KEYS = [
+    bytes.fromhex(key)
+    for key in (
+        "04d571b7f148c5e4232c3814f777d8faeaf1a84216c78d569b71041ffc768a5b2d810fc3bb134dd026b57e65005275aedef43e155f48fc11a32ec790a93312bd58",
+        "0463279c0c0866e50c05c799d32bd6bab0188b6de06536d1109d2ed9ce76cb335c490e55aee10cc901215132e853097d5432eda06b792073bd7740c94ce4516cb1",
+        "0443aedbb6f7e71c563f8ed2ef64ec9981482519e7ef4f4aa98b27854e8c49126d4956d300ab45fdc34cd26bc8710de0a31dbdf6de7435fd0b492be70ac75fde58",
+        "04877c39fd7c62237e038235e9c075dab261630f78eeb8edb92487159fffedfdf6046c6f8b881fa407c4a4ce6c28de0b19c1f4e29f1fcbc5a58ffd1432a3e0938a",
+        "047384c51ae81add0a523adbb186c91b906ffb64c2c765802bf26dbd13bdf12c319e80c2213a136c8ee03d7874fd22b70d68e7dee469decfbbb510ee9a460cda45",
+    )
+]
+
+V2_BOARDLOADER_KEYS = [
+    bytes.fromhex(key)
+    for key in (
+        "0eb9856be9ba7e972c7f34eac1ed9b6fd0efd172ec00faf0c589759da4ddfba0",
+        "ac8ab40b32c98655798fd5da5e192be27a22306ea05c6d277cdff4a3f4125cd8",
+        "ce0fcd12543ef5936cf2804982136707863d17295faced72af171d6e6513ff06",
+    )
+]
+
+V2_BOARDLOADER_DEV_KEYS = [
+    bytes.fromhex(key)
+    for key in (
+        "db995fe25169d141cab9bbba92baa01f9f2e1ece7df4cb2ac05190f37fcc1f9d",
+        "2152f8d19b791d24453242e15f2eab6cb7cffa7b6a5ed30097960e069881db12",
+        "22fc297792f0b6ffc0bfcfdb7edb0c0aa14e025a365ec0e342e86e3829cb74b6",
+    )
+]
+
+V2_BOOTLOADER_KEYS = [
+    bytes.fromhex(key)
+    for key in (
+        "c2c87a49c5a3460977fbb2ec9dfe60f06bd694db8244bd4981fe3b7a26307f3f",
+        "80d036b08739b846f4cb77593078deb25dc9487aedcf52e30b4fb7cd7024178a",
+        "b8307a71f552c60a4cbb317ff48b82cdbf6b6bb5f04c920fec7badf017883751",
+    )
+]
+
+V2_SIGS_REQUIRED = 2
+
+ONEV2_CHUNK_SIZE = 1024 * 64
+V2_CHUNK_SIZE = 1024 * 128

python/src/trezorlib/firmware/core.py

@@ -0,0 +1,187 @@
+import hashlib
+import typing as t
+from copy import copy
+from enum import Enum
+
+import construct as c
+from construct_classes import Struct, subcon
+
+from .. import cosi
+from ..tools import EnumAdapter, TupleAdapter
+from . import consts, util
+from .vendor import VendorHeader
+
+__all__ = [
+    "HeaderType",
+    "FirmwareHeader",
+    "FirmwareImage",
+    "VendorFirmware",
+]
+
+
+class HeaderType(Enum):
+    FIRMWARE = b"TRZF"
+    BOOTLOADER = b"TRZB"
+
+
+class FirmwareHeader(Struct):
+    magic: HeaderType
+    header_len: int
+    expiry: int
+    code_length: int
+    version: t.Tuple[int, int, int, int]
+    fix_version: t.Tuple[int, int, int, int]
+    hashes: t.Sequence[bytes]
+
+    v1_signatures: t.Sequence[bytes]
+    v1_key_indexes: t.Sequence[int]
+
+    sigmask: int
+    signature: bytes
+
+    # fmt: off
+    SUBCON = c.Struct(
+        "_start_offset" / c.Tell,
+        "magic" / EnumAdapter(c.Bytes(4), HeaderType),
+        "header_len" / c.Int32ul,
+        "expiry" / c.Int32ul,
+        "code_length" / c.Rebuild(
+            c.Int32ul,
+            lambda this:
+                len(this._.code) if "code" in this._
+                else (this.code_length or 0)
+        ),
+        "version" / TupleAdapter(c.Int8ul, c.Int8ul, c.Int8ul, c.Int8ul),
+        "fix_version" / TupleAdapter(c.Int8ul, c.Int8ul, c.Int8ul, c.Int8ul),
+        "_reserved" / c.Padding(8),
+        "hashes" / c.Bytes(32)[16],
+
+        "v1_signatures" / c.Bytes(64)[consts.V1_SIGNATURE_SLOTS],
+        "v1_key_indexes" / c.Int8ul[consts.V1_SIGNATURE_SLOTS],  # pylint: disable=E1136
+
+        "_reserved" / c.Padding(220),
+        "sigmask" / c.Byte,
+        "signature" / c.Bytes(64),
+
+        "_end_offset" / c.Tell,
+
+        "_rebuild_header_len" / c.If(
+            c.this.version[0] > 1,
+            c.Pointer(
+                c.this._start_offset + 4,
+                c.Rebuild(c.Int32ul, c.this._end_offset - c.this._start_offset)
+            ),
+        ),
+    )
+    # fmt: on
+
+
+class FirmwareImage(Struct):
+    """Raw firmware image.
+
+    Consists of firmware header and code block.
+    This is the expected format of firmware binaries for Trezor One, or bootloader images
+    for Trezor T."""
+
+    header: FirmwareHeader = subcon(FirmwareHeader)
+    _code_offset: int
+    code: bytes
+
+    SUBCON = c.Struct(
+        "header" / FirmwareHeader.SUBCON,
+        "_code_offset" / c.Tell,
+        "code" / c.Bytes(c.this.header.code_length),
+        c.Terminated,
+    )
+
+    HASH_PARAMS = util.FirmwareHashParameters(
+        hash_function=hashlib.blake2s,
+        chunk_size=consts.V2_CHUNK_SIZE,
+        padding_byte=None,
+    )
+
+    def code_hashes(self) -> t.List[bytes]:
+        """Calculate hashes of chunks of `code`.
+
+        Assume that the first `code_offset` bytes of `code` are taken up by the header.
+        """
+        hashes = []
+        # End offset for each chunk. Normally this would be (i+1)*chunk_size for i-th chunk,
+        # but the first chunk is shorter by code_offset, so all end offsets are shifted.
+        ends = [
+            (i + 1) * self.HASH_PARAMS.chunk_size - self._code_offset for i in range(16)
+        ]
+        start = 0
+        for end in ends:
+            chunk = self.code[start:end]
+            # padding for last non-empty chunk
+            if (
+                self.HASH_PARAMS.padding_byte is not None
+                and start < len(self.code)
+                and end > len(self.code)
+            ):
+                chunk += self.HASH_PARAMS.padding_byte[0:1] * (end - start - len(chunk))
+
+            if not chunk:
+                hashes.append(b"\0" * 32)
+            else:
+                hashes.append(self.HASH_PARAMS.hash_function(chunk).digest())
+
+            start = end
+
+        return hashes
+
+    def validate_code_hashes(self) -> None:
+        if self.code_hashes() != self.header.hashes:
+            raise util.FirmwareIntegrityError("Invalid firmware data.")
+
+    def digest(self) -> bytes:
+        header = copy(self.header)
+        header.hashes = self.code_hashes()
+        header.signature = b"\x00" * 64
+        header.sigmask = 0
+        header.v1_key_indexes = [0] * consts.V1_SIGNATURE_SLOTS
+        header.v1_signatures = [b"\x00" * 64] * consts.V1_SIGNATURE_SLOTS
+        return self.HASH_PARAMS.hash_function(header.build()).digest()
+
+
+class VendorFirmware(Struct):
+    """Firmware image prefixed by a vendor header.
+
+    This is the expected format of firmware binaries for Trezor T."""
+
+    vendor_header: VendorHeader = subcon(VendorHeader)
+    firmware: FirmwareImage = subcon(FirmwareImage)
+
+    SUBCON = c.Struct(
+        "vendor_header" / VendorHeader.SUBCON,
+        "firmware" / FirmwareImage.SUBCON,
+        c.Terminated,
+    )
+
+    def digest(self) -> bytes:
+        return self.firmware.digest()
+
+    def verify(self, _public_keys: t.Sequence[bytes] = ()) -> None:
+        if _public_keys:
+            raise ValueError("Cannot supply custom keys for vendor firmware.")
+
+        self.firmware.validate_code_hashes()
+
+        self.vendor_header.verify()
+        digest = self.digest()
+        try:
+            cosi.verify(
+                self.firmware.header.signature,
+                digest,
+                self.vendor_header.sig_m,
+                self.vendor_header.pubkeys,
+                self.firmware.header.sigmask,
+            )
+        except Exception:
+            raise util.InvalidSignatureError("Invalid firmware signature.")
+
+        # XXX expiry is not used now
+        # now = time.gmtime()
+        # if time.gmtime(fw.vendor_header.expiry) < now:
+        #     raise ValueError("Vendor header expired.")

python/src/trezorlib/firmware/legacy.py

@@ -0,0 +1,124 @@
+import hashlib
+import typing as t
+from dataclasses import field
+
+import construct as c
+import ecdsa
+from construct_classes import Struct, subcon
+
+from . import consts, util
+from .core import FirmwareImage
+
+__all__ = [
+    "LegacyFirmware",
+    "LegacyV2Firmware",
+    "check_sig_v1",
+]
+
+
+def check_sig_v1(
+    digest: bytes,
+    key_indexes: t.Sequence[int],
+    signatures: t.Sequence[bytes],
+    public_keys: t.Sequence[bytes],
+) -> None:
+    """Validate signatures of `digest` using the Trezor One V1 method."""
+    distinct_indexes = set(i for i in key_indexes if i != 0)
+    if not distinct_indexes:
+        raise util.Unsigned
+
+    if len(distinct_indexes) < len(key_indexes):
+        raise util.InvalidSignatureError(
+            f"Not enough distinct signatures (found {len(distinct_indexes)}, need {len(key_indexes)})"
+        )
+
+    for i in range(len(key_indexes)):
+        key_idx = key_indexes[i] - 1
+        signature = signatures[i]
+
+        if key_idx >= len(public_keys):
+            # unknown pubkey
+            raise util.InvalidSignatureError(f"Unknown key in slot {i}")
+
+        pubkey = public_keys[key_idx][1:]
+        verify = ecdsa.VerifyingKey.from_string(pubkey, curve=ecdsa.curves.SECP256k1)
+        try:
+            verify.verify_digest(signature, digest)
+        except ecdsa.BadSignatureError as e:
+            raise util.InvalidSignatureError(f"Invalid signature in slot {i}") from e
+
+
+class LegacyV2Firmware(FirmwareImage):
+    """Firmware image in the format used by Trezor One 1.8.0 and newer."""
+
+    HASH_PARAMS = util.FirmwareHashParameters(
+        hash_function=hashlib.sha256,
+        chunk_size=consts.ONEV2_CHUNK_SIZE,
+        padding_byte=b"\xff",
+    )
+
+    def verify(
+        self, public_keys: t.Sequence[bytes] = consts.V1_BOOTLOADER_KEYS
+    ) -> None:
+        self.validate_code_hashes()
+        check_sig_v1(
+            self.digest(),
+            self.header.v1_key_indexes,
+            self.header.v1_signatures,
+            public_keys,
+        )
+
+    def verify_unsigned(self) -> None:
+        self.validate_code_hashes()
+        if any(i != 0 for i in self.header.v1_key_indexes):
+            raise util.InvalidSignatureError("Firmware is not unsigned.")
+
+
+class LegacyFirmware(Struct):
+    """Legacy firmware image.
+    Consists of a custom header and code block.
+    This is the expected format of firmware binaries for Trezor One pre-1.8.0.
+
+    The code block can optionally be interpreted as a new-style firmware image. That is the
+    expected format of firmware binary for Trezor One version 1.8.0, which can be installed
+    by both the older and the newer bootloader."""
+
+    key_indexes: t.List[int]
+    signatures: t.List[bytes]
+    code: bytes
+    flags: t.Dict[str, t.Any] = field(default_factory=dict)
+    embedded_v2: t.Optional[LegacyV2Firmware] = subcon(LegacyV2Firmware, default=None)
+
+    # fmt: off
+    SUBCON = c.Struct(
+        "magic" / c.Const(b"TRZR"),
+        "code_length" / c.Rebuild(c.Int32ul, c.len_(c.this.code)),
+        "key_indexes" / c.Int8ul[consts.V1_SIGNATURE_SLOTS],  # pylint: disable=E1136
+        "flags" / c.BitStruct(
+            c.Padding(7),
+            "restore_storage" / c.Flag,
+        ),
+        "_reserved" / c.Padding(52),
+        "signatures" / c.Bytes(64)[consts.V1_SIGNATURE_SLOTS],
+        "code" / c.Bytes(c.this.code_length),
+        c.Terminated,
+
+        "embedded_v2" / c.RestreamData(c.this.code, c.Optional(LegacyV2Firmware.SUBCON)),
+    )
+    # fmt: on
+
+    def digest(self) -> bytes:
+        return hashlib.sha256(self.code).digest()
+
+    def verify(
+        self, public_keys: t.Sequence[bytes] = consts.V1_BOOTLOADER_KEYS
+    ) -> None:
+        check_sig_v1(
+            self.digest(),
+            self.key_indexes,
+            self.signatures,
+            public_keys,
+        )
+
+        if self.embedded_v2:
+            self.embedded_v2.verify(consts.V1_BOOTLOADER_KEYS)

python/src/trezorlib/firmware/util.py

@@ -0,0 +1,34 @@
+import typing as t
+from dataclasses import dataclass
+
+from typing_extensions import Protocol
+
+
+class FirmwareIntegrityError(Exception):
+    pass
+
+
+class InvalidSignatureError(FirmwareIntegrityError):
+    pass
+
+
+class Unsigned(FirmwareIntegrityError):
+    pass
+
+
+class DigestCalculator(Protocol):
+    def update(self, __data: bytes) -> None:
+        ...
+
+    def digest(self) -> bytes:
+        ...
+
+
+Hasher = t.Callable[[bytes], DigestCalculator]
+
+
+@dataclass
+class FirmwareHashParameters:
+    hash_function: Hasher
+    chunk_size: int
+    padding_byte: t.Optional[bytes]

python/src/trezorlib/firmware/vendor.py

@@ -0,0 +1,128 @@
+import hashlib
+import typing as t
+from copy import copy
+
+import construct as c
+from construct_classes import Struct, subcon
+
+from .. import cosi
+from ..toif import ToifStruct
+from ..tools import TupleAdapter
+from . import consts, util
+
+__all__ = [
+    "VendorTrust",
+    "VendorHeader",
+]
+
+
+def _transform_vendor_trust(data: bytes) -> bytes:
+    """Byte-swap and bit-invert the VendorTrust field.
+
+    Vendor trust is interpreted as a bitmask in a 16-bit little-endian integer,
+    with the added twist that 0 means set and 1 means unset.
+    We feed it to a `BitStruct` that expects a big-endian sequence where bits have
+    the traditional meaning. We must therefore do a bitwise negation of each byte,
+    and return them in reverse order. This is the same transformation both ways,
+    fortunately, so we don't need two separate functions.
+    """
+    return bytes(~b & 0xFF for b in data)[::-1]
+
+
+class VendorTrust(Struct):
+    show_vendor_string: bool
+    require_user_click: bool
+    red_background: bool
+    delay: int
+
+    _reserved: int = 0
+
+    SUBCON = c.Transformed(
+        c.BitStruct(
+            "_reserved" / c.Default(c.BitsInteger(9), 0),
+            "show_vendor_string" / c.Flag,
+            "require_user_click" / c.Flag,
+            "red_background" / c.Flag,
+            "delay" / c.BitsInteger(4),
+        ),
+        _transform_vendor_trust,
+        2,
+        _transform_vendor_trust,
+        2,
+    )
+
+
+class VendorHeader(Struct):
+    header_len: int
+    expiry: int
+    version: t.Tuple[int, int]
+    sig_m: int
+    # sig_n: int
+    pubkeys: t.List[bytes]
+    text: str
+    image: t.Dict[str, t.Any]
+    sigmask: int
+    signature: bytes
+
+    trust: VendorTrust = subcon(VendorTrust)
+
+    # fmt: off
+    SUBCON = c.Struct(
+        "_start_offset" / c.Tell,
+        "magic" / c.Const(b"TRZV"),
+        "header_len" / c.Int32ul,
+        "expiry" / c.Int32ul,
+        "version" / TupleAdapter(c.Int8ul, c.Int8ul),
+        "sig_m" / c.Int8ul,
+        "sig_n" / c.Rebuild(c.Int8ul, c.len_(c.this.pubkeys)),
+        "trust" / VendorTrust.SUBCON,
+        "_reserved" / c.Padding(14),
+        "pubkeys" / c.Bytes(32)[c.this.sig_n],
+        "text" / c.Aligned(4, c.PascalString(c.Int8ul, "utf-8")),
+        "image" / ToifStruct,
+        "_end_offset" / c.Tell,
+
+        "_min_header_len" / c.Check(c.this.header_len > (c.this._end_offset - c.this._start_offset) + 65),
+        "_header_len_aligned" / c.Check(c.this.header_len % 512 == 0),
+
+        c.Padding(c.this.header_len - c.this._end_offset + c.this._start_offset - 65),
+        "sigmask" / c.Byte,
+        "signature" / c.Bytes(64),
+    )
+    # fmt: on
+
+    def digest(self) -> bytes:
+        cpy = copy(self)
+        cpy.sigmask = 0
+        cpy.signature = b"\x00" * 64
+        return hashlib.blake2s(cpy.build()).digest()
+
+    def vhash(self) -> bytes:
+        h = hashlib.blake2s()
+        sig_n = len(self.pubkeys)
+        h.update(self.sig_m.to_bytes(1, "little"))
+        h.update(sig_n.to_bytes(1, "little"))
+        for i in range(8):
+            if i < sig_n:
+                h.update(self.pubkeys[i])
+            else:
+                h.update(b"\x00" * 32)
+        return h.digest()
+
+    def verify(self, pubkeys: t.Sequence[bytes] = consts.V2_BOOTLOADER_KEYS) -> None:
+        digest = self.digest()
+        try:
+            cosi.verify(
+                self.signature,
+                digest,
+                consts.V2_SIGS_REQUIRED,
+                pubkeys,
+                self.sigmask,
+            )
+        except Exception:
+            raise util.InvalidSignatureError("Invalid vendor header signature.")
+
+        # XXX expiry is not used now
+        # now = time.gmtime()
+        # if time.gmtime(fw.vendor_header.expiry) < now:
+        #     raise ValueError("Vendor header expired.")

python/src/trezorlib/tools.py

@@ -389,3 +389,14 @@ class EnumAdapter(construct.Adapter):
             return self.enum(obj)
         except ValueError:
             return obj
+
+
+class TupleAdapter(construct.Adapter):
+    def __init__(self, *subcons: Any) -> None:
+        super().__init__(construct.Sequence(*subcons))
+
+    def _encode(self, obj: Any, ctx: Any, path: Any):
+        return obj
+
+    def _decode(self, obj: Any, ctx: Any, path: Any):
+        return tuple(obj)

python/tests/test_firmware.py

@@ -0,0 +1,153 @@
+from pathlib import Path
+
+import construct
+import pytest
+import requests
+
+from trezorlib import firmware
+from trezorlib.firmware import (
+    VendorFirmware,
+    LegacyFirmware,
+    LegacyV2Firmware,
+    VendorHeader,
+)
+
+CORE_FW_VERSION = "2.4.2"
+CORE_FW_FINGERPRINT = "54ccf155510b5292bd17ed748409d0d135112e24e62eb74184639460beecb213"
+LEGACY_FW_VERSION = "1.10.3"
+LEGACY_FW_FINGERPRINT = (
+    "bf0cc936a9afbf0a4ae7b727a2817fb69fba432d7230a0ff7b79b4a73b845197"
+)
+
+CORE_FW = f"https://data.trezor.io/firmware/2/trezor-{CORE_FW_VERSION}.bin"
+LEGACY_FW = f"https://data.trezor.io/firmware/1/trezor-{LEGACY_FW_VERSION}.bin"
+
+HERE = Path(__file__).parent
+
+VENDOR_HEADER = (
+    HERE.parent.parent
+    / "core"
+    / "embed"
+    / "vendorheader"
+    / "vendorheader_satoshilabs_signed_prod.bin"
+)
+
+
+def _fetch(url: str, version: str) -> bytes:
+    path = HERE / f"trezor-{version}.bin"
+    if not path.exists():
+        r = requests.get(url)
+        r.raise_for_status()
+        path.write_bytes(r.content)
+    return path.read_bytes()
+
+
+@pytest.fixture()
+def legacy_fw() -> bytes:
+    return _fetch(LEGACY_FW, LEGACY_FW_VERSION)
+
+
+@pytest.fixture()
+def core_fw() -> bytes:
+    return _fetch(CORE_FW, CORE_FW_VERSION)
+
+
+def test_core_basic(core_fw: bytes) -> None:
+    fw = VendorFirmware.parse(core_fw)
+    fw.verify()
+    assert fw.digest().hex() == CORE_FW_FINGERPRINT
+    version_str = ".".join(str(x) for x in fw.firmware.header.version)
+    assert version_str.startswith(CORE_FW_VERSION)
+    assert fw.vendor_header.text == "SatoshiLabs"
+    assert fw.build() == core_fw
+
+
+def test_vendor_header(core_fw: bytes) -> None:
+    fw = VendorFirmware.parse(core_fw)
+
+    vh_data = fw.vendor_header.build()
+    assert vh_data in core_fw
+    assert vh_data == VENDOR_HEADER.read_bytes()
+
+    vh = VendorHeader.parse(vh_data)
+    assert vh == fw.vendor_header
+    vh.verify()
+
+    with pytest.raises(construct.ConstructError):
+        VendorFirmware.parse(vh_data)
+
+
+def test_core_code_hashes(core_fw: bytes) -> None:
+    fw = VendorFirmware.parse(core_fw)
+    fw.firmware.header.hashes = []
+    assert fw.digest().hex() == CORE_FW_FINGERPRINT
+
+
+def test_legacy_basic(legacy_fw: bytes) -> None:
+    fw = LegacyFirmware.parse(legacy_fw)
+    fw.verify()
+    assert fw.digest().hex() == LEGACY_FW_FINGERPRINT
+    assert fw.build() == legacy_fw
+
+
+def test_unsigned(legacy_fw: bytes) -> None:
+    legacy = LegacyFirmware.parse(legacy_fw)
+
+    legacy.verify()
+    legacy.key_indexes = [0, 0, 0]
+    legacy.signatures = [b"", b"", b""]
+
+    with pytest.raises(firmware.Unsigned):
+        legacy.verify()
+
+    assert legacy.embedded_v2 is not None
+    legacy.embedded_v2.verify()
+
+    legacy.embedded_v2.header.v1_key_indexes = [0, 0, 0]
+    legacy.embedded_v2.header.v1_signatures = [b"", b"", b""]
+    with pytest.raises(firmware.Unsigned):
+        legacy.embedded_v2.verify()
+
+
+def test_disallow_unsigned(core_fw: bytes) -> None:
+    core = VendorFirmware.parse(core_fw)
+    core.firmware.header.sigmask = 0
+    core.firmware.header.signature = b""
+    with pytest.raises(firmware.InvalidSignatureError):
+        core.verify()
+
+
+def test_embedded_v2(legacy_fw: bytes) -> None:
+    legacy = LegacyFirmware.parse(legacy_fw)
+    assert legacy.embedded_v2 is not None
+    legacy.embedded_v2.verify()
+
+    embedded_data = legacy.embedded_v2.build()
+    cutoff_data = legacy_fw[256:]
+    assert cutoff_data == embedded_data
+    embedded = LegacyV2Firmware.parse(cutoff_data)
+    assert embedded == legacy.embedded_v2
+
+
+def test_integrity_legacy(legacy_fw: bytes) -> None:
+    legacy = LegacyFirmware.parse(legacy_fw)
+    legacy.verify()
+
+    modified_data = bytearray(legacy_fw)
+    modified_data[-1] ^= 0x01
+    modified = LegacyFirmware.parse(modified_data)
+    assert modified.digest() != legacy.digest()
+    with pytest.raises(firmware.InvalidSignatureError):
+        modified.verify()
+
+
+def test_integrity_core(core_fw: bytes) -> None:
+    core = VendorFirmware.parse(core_fw)
+    core.verify()
+
+    modified_data = bytearray(core_fw)
+    modified_data[-1] ^= 0x01
+    modified = VendorFirmware.parse(modified_data)
+    assert modified.digest() != core.digest()
+    with pytest.raises(firmware.FirmwareIntegrityError):
+        modified.verify()

python/tools/firmware-fingerprint.py

@@ -22,7 +22,6 @@ from typing import BinaryIO, TextIO
 import click
 
 from trezorlib import firmware
-from trezorlib._internal import firmware_headers
 
 
 @click.command()
@@ -33,20 +32,11 @@ def firmware_fingerprint(filename: BinaryIO, output: TextIO) -> None:
     data = filename.read()
 
     try:
-        version, fw = firmware.parse(data)
+        click.echo(firmware.parse(data).digest().hex(), file=output)
-
-        # Unsigned production builds for Trezor T do not have valid code hashes.
-        # Use the internal module which recomputes them first.
-        if version == firmware.FirmwareFormat.TREZOR_T:
-            fingerprint = firmware_headers.FirmwareImage(fw).digest()
-        else:
-            fingerprint = firmware.digest(version, fw)
     except Exception as e:
         click.echo(e, err=True)
         sys.exit(2)
 
-    click.echo(fingerprint.hex(), file=output)
-
 
 if __name__ == "__main__":
     firmware_fingerprint()