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tools: add firmware signature check (against its vendor header)

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Pavol Rusnak 2017-10-25 23:23:41 +02:00
parent 46fdb8bcb4
commit bdbbf0e5e8
No known key found for this signature in database
GPG Key ID: 91F3B339B9A02A3D
1 changed files with 21 additions and 4 deletions
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tools/binctl
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@ -6,6 +6,8 @@ import sys
import struct
import binascii
import pyblake2
from trezorlib import ed25519raw, ed25519cosi
@ -89,7 +91,7 @@ class BinImage(object):
class FirmwareImage(BinImage):
def __init__(self, data, vhdrlen):
super(FirmwareImage, self).__init__(data[vhdrlen:], magic=b'TRZF', max_size=7 * 128 * 1024)
super(FirmwareImage, self).__init__(data[vhdrlen:], magic=b'TRZF', max_size=6 * 128 * 1024)
self.vhdrlen = vhdrlen
self.vheader = data[:vhdrlen]
@ -103,7 +105,7 @@ class FirmwareImage(BinImage):
class BootloaderImage(BinImage):
def __init__(self, data):
super(BootloaderImage, self).__init__(data, magic=b'TRZB', max_size=64 * 1024 + 7 * 128 * 1024)
super(BootloaderImage, self).__init__(data, magic=b'TRZB', max_size=1 * 128 * 1024)
class VendorHeader(object):
@ -158,6 +160,7 @@ class VendorHeader(object):
print(' * vimg : (%d bytes)' % len(self.vimg))
print(' * sigmask :', format_sigmask(self.sigmask))
print(' * sig :', binascii.hexlify(self.sig).decode('ascii'))
print()
def serialize_header(self, sig=True):
header = struct.pack('<4sIIBBBBB',
@ -183,7 +186,6 @@ class VendorHeader(object):
if bin(sigmask).count('1') != self.vsig_m:
raise Exception('invalid number of indexes (vsig_m expected %d, got %d)' % (self.vsig_m, bin(sigmask).count('1')))
# sign
header = self.serialize_header(sig=False)
self.sigmask = sigmask
self.sig = signature
@ -204,7 +206,22 @@ def binopen(filename):
return vheader
subdata = data[vheader.hdrlen:]
if subdata[:4] == b'TRZF':
return FirmwareImage(data, vheader.hdrlen)
firmware = FirmwareImage(data, vheader.hdrlen)
# check signatures against signing keys in the vendor header
if firmware.sigmask > 0:
pk = [vheader.vpub[i] for i in range(8) if firmware.sigmask & (1 << i)]
global_pk = ed25519cosi.combine_keys(pk)
subdata_nosig = bytearray(subdata)
subdata_nosig[512 - 65:512] = 65 * b'\x00'
digest = pyblake2.blake2s(subdata_nosig).digest()
try:
ed25519raw.checkvalid(firmware.sig, digest, global_pk)
print('Firmware signature OK')
except:
print('Firmware signature INCORRECT')
else:
print('No firmware signature')
return firmware
if magic == b'TRZF':
return FirmwareImage(data, 0)
raise Exception('Unknown file format')