mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-10-31 20:39:48 +00:00
94 lines
3.1 KiB
Python
Executable File
94 lines
3.1 KiB
Python
Executable File
#!/usr/bin/env python3
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import sys
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from hashlib import sha256
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class Signatures:
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# offsets from T1 firmware hash
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sig_offsets = [544, 608, 672]
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sigindex_offsets = [736, 737, 738]
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signature_pairs = [] # list of tupes (int, bytes)
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def __init__(self, filename):
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"""Load FW, zero out signature fiels, compute header hash"""
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self.fw_image = None # mutable bytearray
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self.load_fw(filename)
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self.header_hash = sha256(self.get_header()).digest()
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print(f"Loaded FW image with header hash {self.header_hash_hex()}")
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def load_fw(self, filename):
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"""Load FW and zero out signature fiels"""
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with open(filename, "rb") as f:
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data = f.read()
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self.fw_image = bytearray(data)
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self.zero_sig_fields()
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def zero_sig_fields(self):
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"""Zero out signature fields to be able to compute header hash"""
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for i in range(3):
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sigindex_ofs = self.sigindex_offsets[i]
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sig_ofs = self.sig_offsets[i]
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self.fw_image[sigindex_ofs] = 0
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self.fw_image[sig_ofs : sig_ofs + 64] = b"\x00" * 64
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def header_hash_hex(self):
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return self.header_hash.hex()
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def get_header(self):
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"""Return header with zeroed out signatures as copy"""
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return bytes(self.fw_image[:1024])
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def patch_signatures(self):
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"""
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Patch signatures from signature_pairs.
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Requires filling signature_pairs beforehand.
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"""
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assert len(self.signature_pairs) <= 3
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for i in range(len(self.signature_pairs)):
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sigindex_ofs = self.sigindex_offsets[i]
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sig_ofs = self.sig_offsets[i]
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(sigindex, sig) = self.signature_pairs[i]
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print(f"Patching sigindex {sigindex} at offset {sigindex_ofs}")
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assert 1 <= sigindex <= 5
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self.fw_image[sigindex_ofs] = sigindex
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print(f"Patching signature {sig.hex()} at offset {sig_ofs}")
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assert len(sig) == 64
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self.fw_image[sig_ofs : sig_ofs + 64] = sig
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def write_output_fw(self, filename):
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print(f"Writing output signed FW file {filename}")
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with open(filename, "wb") as signed_fw_file:
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signed_fw_file.write(self.fw_image)
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if __name__ == "__main__":
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# arg1 - unsigned trezor.bin FW
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# arg2 - list of 3 signatures and indexes in this format (split by single space):
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# index_num signature
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# e.g.
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# 1 adec956df6282c15ee4344b4cf6edbe435ed4bb13b2b7bebb9920f3d1c4a791a446e492f3ff9b86ca43f28cfce1be97c4eefa65e505e8a936876f01833366d5d
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in_fw_fname = sys.argv[1]
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signatures_fname = sys.argv[2]
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signatures = Signatures(in_fw_fname)
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i = 0
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for line in open(signatures_fname):
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i += 1
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print(f"Parsing sig line {i} - {line}")
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idx, sig = line.rstrip().split(" ")
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idx = int(idx)
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sig = bytes.fromhex(sig)
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assert idx in range(1, 6) # 1 <= idx <= 5
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assert len(sig) == 64
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signatures.signature_pairs.append((idx, sig))
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out_fw_name = in_fw_fname + ".signed"
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signatures.patch_signatures()
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signatures.write_output_fw(out_fw_name)
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