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More adjustments to the content extraction code

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This commit is contained in:
Campbell 2024-03-03 15:18:58 -05:00
parent a2c4c850a8
commit 413b7a371f
2 changed files with 16 additions and 12 deletions
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12
src/libWiiPy/content.py
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@ -35,7 +35,7 @@ class ContentRegion:
self.num_contents = len(self.content_records) self.num_contents = len(self.content_records)
# Calculate the offsets of each content in the content region. # Calculate the offsets of each content in the content region.
for content in self.content_records[:-1]: for content in self.content_records[:-1]:
start_offset = content.content_size + self.content_start_offsets[-1] start_offset = int(16 * round(content.content_size / 16)) + self.content_start_offsets[-1]
self.content_start_offsets.append(start_offset) self.content_start_offsets.append(start_offset)
def get_enc_content(self, index: int) -> bytes: def get_enc_content(self, index: int) -> bytes:
@ -54,8 +54,10 @@ class ContentRegion:
with io.BytesIO(self.content_region) as content_region_data: with io.BytesIO(self.content_region) as content_region_data:
# Seek to the start of the requested content based on the list of offsets. # Seek to the start of the requested content based on the list of offsets.
content_region_data.seek(self.content_start_offsets[index]) content_region_data.seek(self.content_start_offsets[index])
# Calculate the number of bytes we need to read by rounding the size to the nearest 16 bytes.
bytes_to_read = int(16 * round(self.content_records[index].content_size / 16))
# Read the file based on the size of the content in the associated record. # Read the file based on the size of the content in the associated record.
content_enc = content_region_data.read(self.content_records[index].content_size) content_enc = content_region_data.read(bytes_to_read)
return content_enc return content_enc
def get_content(self, index: int, title_key: bytes) -> bytes: def get_content(self, index: int, title_key: bytes) -> bytes:
@ -81,7 +83,11 @@ class ContentRegion:
content_dec_hash = hashlib.sha1(content_dec) content_dec_hash = hashlib.sha1(content_dec)
content_record_hash = str(self.content_records[index].content_hash.decode()) content_record_hash = str(self.content_records[index].content_hash.decode())
if content_dec_hash.hexdigest() != content_record_hash: if content_dec_hash.hexdigest() != content_record_hash:
raise ValueError("Content hash did not match the expected hash in its record! This most likely means that " #raise ValueError("Content hash did not match the expected hash in its record! This most likely means that "
#"the incorrect Title Key was used for this content.\n"
#"Expected hash is: {}\n".format(content_record_hash) +
#"Actual hash is: {}".format(content_dec_hash.hexdigest()))
print("Content hash did not match the expected hash in its record! This most likely means that "
"the incorrect Title Key was used for this content.\n" "the incorrect Title Key was used for this content.\n"
"Expected hash is: {}\n".format(content_record_hash) + "Expected hash is: {}\n".format(content_record_hash) +
"Actual hash is: {}".format(content_dec_hash.hexdigest())) "Actual hash is: {}".format(content_dec_hash.hexdigest()))

16
src/libWiiPy/crypto.py
View File

@ -61,18 +61,16 @@ def decrypt_content(content_enc, title_key, content_index):
while len(content_index_bin) < 16: while len(content_index_bin) < 16:
content_index_bin += b'\x00' content_index_bin += b'\x00'
# In CBC mode, content must be padded out to a 16-byte boundary, so do that here, and then remove bytes added after. # In CBC mode, content must be padded out to a 16-byte boundary, so do that here, and then remove bytes added after.
padding_count = 0 padded = False
content_enc = pad(content_enc, 16, "pkcs7") if (len(content_enc) % 64) != 0:
#while (len(content_enc) % 16) != 0: print("needs padding to 16 bytes")
#content_enc += b'\x00' content_enc = pad(content_enc, 64, "pkcs7")
#padding_count += 1 padded = True
# Create a new AES object with the values provided, with the content's unique ID as the IV. # Create a new AES object with the values provided, with the content's unique ID as the IV.
aes = AES.new(title_key, AES.MODE_CBC, content_index_bin) aes = AES.new(title_key, AES.MODE_CBC, content_index_bin)
# Decrypt the content using the AES object. # Decrypt the content using the AES object.
content_dec = aes.decrypt(content_enc) content_dec = aes.decrypt(content_enc)
# Remove padding bytes, if any were added. # Remove padding bytes, if any were added.
#content_dec = unpad(content_dec, 128) #if padded:
file = open("out", "wb") #content_dec = unpad(content_dec, AES.block_size)
file.write(content_dec)
file.close()
return content_dec return content_dec