Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add data validation #33

Draft
wants to merge 1 commit into
base: master
Choose a base branch
from
Draft

Add data validation #33

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
52 changes: 50 additions & 2 deletions xbe/__init__.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
import logging
import struct
import time
import hashlib

from enum import IntFlag
from typing import (
Expand Down Expand Up @@ -543,7 +544,6 @@ class InitFlags(IntFlag):
]
_enummap_ = {"init_flags": InitFlags}


class XbeImageHeaderExtendedType1(XbeImageHeader):
"""
XBE Extended Image Header structure (Type 1)
Expand Down Expand Up @@ -781,10 +781,38 @@ def _init_from_data(self, data: bytes) -> None:
assert self.header.image_header_size > ctypes.sizeof(XbeImageHeader)

# FIXME: Validate magic
# FIXME: Validate signature/integrity
log.debug("Image Header:\n%s", self.header.dumps(indent=2))

# FIXME: alternate modulus values for debug/chihiro
retail_modulus = bytes([
0xd3,0xd7,0x4e,0xe5, 0x66,0x3d,0xd7,0xe6, 0xc2,0xd4,0xa3,0xa1, 0xf2,0x17,0x36,0xd4,
0x2e,0x52,0xf6,0xd2, 0x02,0x10,0xf5,0x64, 0x9c,0x34,0x7b,0xff, 0xef,0x7f,0xc2,0xee,
0xbd,0x05,0x8b,0xde, 0x79,0xb4,0x77,0x8e, 0x5b,0x8c,0x14,0x99, 0xe3,0xae,0xc6,0x73,
0x72,0x73,0xb5,0xfb, 0x01,0x5b,0x58,0x46, 0x6d,0xfc,0x8a,0xd6, 0x95,0xda,0xed,0x1b,
0x2e,0x2f,0xa2,0x29, 0xe1,0x3f,0xf1,0xb9, 0x5b,0x64,0x51,0x2e, 0xa2,0xc0,0xf7,0xba,
0xb3,0x3e,0x8a,0x75, 0xff,0x06,0x92,0x5c, 0x07,0x26,0x75,0x79, 0x10,0x5d,0x47,0xbe,
0xd1,0x6a,0x52,0x90, 0x0b,0xae,0x6a,0x0b, 0x33,0x44,0x93,0x5e, 0xf9,0x9d,0xfb,0x15,
0xd9,0xa4,0x1c,0xcf, 0x6f,0xe4,0x71,0x94, 0xbe,0x13,0x00,0xa8, 0x52,0xca,0x07,0xbd,
0x27,0x98,0x01,0xa1, 0x9e,0x4f,0xa3,0xed, 0x9f,0xa0,0xaa,0x73, 0xc4,0x71,0xf3,0xe9,
0x4e,0x72,0x42,0x9c, 0xf0,0x39,0xce,0xbe, 0x03,0x76,0xfa,0x2b, 0x89,0x14,0x9a,0x81,
0x16,0xc1,0x80,0x8c, 0x3e,0x6b,0xaa,0x05, 0xec,0x67,0x5a,0xcf, 0xa5,0x70,0xbd,0x60,
0x0c,0xe8,0x37,0x9d, 0xeb,0xf4,0x52,0xea, 0x4e,0x60,0x9f,0xe4, 0x69,0xcf,0x52,0xdb,
0x68,0xf5,0x11,0xcb, 0x57,0x8f,0x9d,0xa1, 0x38,0x0a,0x0c,0x47, 0x1b,0xb4,0x6c,0x5a,
0x53,0x6e,0x26,0x98, 0xf1,0x88,0xae,0x7c, 0x96,0xbc,0xf6,0xbf, 0xb0,0x47,0x9a,0x8d,
0xe4,0xb3,0xe2,0x98, 0x85,0x61,0xb1,0xca, 0x5f,0xf7,0x98,0x51, 0x2d,0x83,0x81,0x76,
0x0c,0x88,0xba,0xd4, 0xc2,0xd5,0x3c,0x14, 0xc7,0x72,0xda,0x7e, 0xbd,0x1b,0x4b,0xa4
])

# Validate header signature
self.header_data = data[0 : self.header.headers_size]
header_data_digest = calc_digest(self.header_data, 260, self.header.headers_size - 260)
key_val = int.from_bytes(retail_modulus, byteorder='little', signed=False)
sig_val = int.from_bytes(bytes(self.header.signature), byteorder='little', signed=False)
decrypted_sig_val = pow(sig_val, 65537, key_val)
decrypted_sig_bytes = decrypted_sig_val.to_bytes((decrypted_sig_val.bit_length() + 7) // 8, byteorder='little', signed=False)
self.header.signature_valid = decrypted_sig_bytes[:len(header_data_digest)] == header_data_digest[::-1]
if not self.header.signature_valid:
log.warning("Header signature invalid.")

# Load debug pathname, filename
self.pathname = self.get_cstring_from_offset(
Expand Down Expand Up @@ -862,6 +890,11 @@ def _init_from_data(self, data: bytes) -> None:
log.debug("Section %d: %s\n%s", i, sec_name, sec_hdr.dumps(indent=2))
sec_hdr_offset += ctypes.sizeof(XbeSectionHeader)

# Validate section data
sec_hdr.digest_valid = bytes(sec_hdr.digest) == calc_digest(sec_data, 0, len(sec_data))
if not sec_hdr.digest_valid:
log.warning("Section digest invalid.")

# Load certificate
cert_offset = self.vaddr_to_file_offset(self.header.certificate_addr)
log.debug("Parsing image certificate at offset %#x", cert_offset)
Expand Down Expand Up @@ -1508,3 +1541,18 @@ def encode_bmp(w: int, h: int, pixels: List["RGBA"]) -> bytes:
)

return hdr + enc

def calc_digest(data: bytes, offset: int, size: int) -> bytes:
sha1 = hashlib.sha1()

# Convert the size to bytes
size_bytes = struct.pack('I', size)

# Update the hash with the size bytes
sha1.update(size_bytes)

# Update the hash with the actual data
sha1.update(data[offset:offset+size])

# Get the final SHA-1 hash
return sha1.digest()