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Full content extraction is working!

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This commit is contained in:
Campbell 2024-03-04 20:48:38 -05:00
parent b3923cfe40
commit 7ca46372b0
4 changed files with 34 additions and 31 deletions
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24
src/libWiiPy/content.py
View File

@ -34,8 +34,12 @@ class ContentRegion:
self.content_region_size = sys.getsizeof(content_region_data)
self.num_contents = len(self.content_records)
# Calculate the offsets of each content in the content region.
# Content is aligned to 16 bytes, however a new content won't start until the next multiple of 64 bytes.
# Because of this, we need to add bytes to the next 64 byte offset if the previous content wasn't that long.
for content in self.content_records[:-1]:
start_offset = int(64 * round(content.content_size / 64)) + self.content_start_offsets[-1]
start_offset = content.content_size + self.content_start_offsets[-1]
if (content.content_size % 64) != 0:
start_offset += 64 - (content.content_size % 64)
self.content_start_offsets.append(start_offset)
def get_enc_content(self, index: int) -> bytes:
@ -54,8 +58,10 @@ class ContentRegion:
with io.BytesIO(self.content_region) as content_region_data:
# Seek to the start of the requested content based on the list of offsets.
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(64 * round(self.content_records[index].content_size / 64))
# Calculate the number of bytes we need to read by adding bytes up the nearest multiple of 16 if needed.
bytes_to_read = self.content_records[index].content_size
if (bytes_to_read % 16) != 0:
bytes_to_read += 16 - (bytes_to_read % 16)
# Read the file based on the size of the content in the associated record.
content_enc = content_region_data.read(bytes_to_read)
return content_enc
@ -77,18 +83,16 @@ class ContentRegion:
"""
# Load the encrypted content at the specified index and then decrypt it with the Title Key.
content_enc = self.get_enc_content(index)
content_dec = decrypt_content(content_enc, title_key, self.content_records[index].index, self.content_records[index].content_size)
content_dec = decrypt_content(content_enc, title_key, self.content_records[index].index,
self.content_records[index].content_size)
# Hash the decrypted content and ensure that the hash matches the one in its Content Record.
# If it does not, then something has gone wrong in the decryption, and an error will be thrown.
content_dec_hash = hashlib.sha1(content_dec)
content_record_hash = str(self.content_records[index].content_hash.decode())
# Compare the hash and throw a ValueError if the hash doesn't match.
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 "
#"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"
raise ValueError("Content hash did not match the expected hash in its record! The incorrect Title Key may"
"have been used!.\n"
"Expected hash is: {}\n".format(content_record_hash) +
"Actual hash is: {}".format(content_dec_hash.hexdigest()))
return content_dec

29
src/libWiiPy/crypto.py
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@ -1,7 +1,5 @@
# "crypto.py" from libWiiPy by NinjaCheetah & Contributors
# https://github.com/NinjaCheetah/libWiiPy
#
# See https://wiibrew.org/wiki/Ticket for details about the TMD format
import struct
from .commonkeys import get_common_key
@ -9,7 +7,7 @@ from Crypto.Cipher import AES
from Crypto.Util.Padding import pad, unpad
def decrypt_title_key(title_key_enc, common_key_index, title_id):
def decrypt_title_key(title_key_enc, common_key_index, title_id) -> bytes:
"""Gets the decrypted version of the encrypted Title Key provided.
Requires the index of the common key to use, and the Title ID of the title that the Title Key is for.
@ -21,7 +19,7 @@ def decrypt_title_key(title_key_enc, common_key_index, title_id):
common_key_index : int
The index of the common key to be returned.
title_id : bytes
The title ID of the tite that the key is for.
The title ID of the title that the key is for.
Returns
-------
@ -39,7 +37,7 @@ def decrypt_title_key(title_key_enc, common_key_index, title_id):
return title_key
def decrypt_content(content_enc, title_key, content_index, content_length):
def decrypt_content(content_enc, title_key, content_index, content_length) -> bytes:
"""Gets the decrypted version of the encrypted content.
Requires the index of the common key to use, and the Title ID of the title that the Title Key is for.
@ -50,6 +48,10 @@ def decrypt_content(content_enc, title_key, content_index, content_length):
The encrypted content.
title_key : bytes
The Title Key for the title the content is from.
content_index : int
The index in the TMD's content record of the content being decrypted.
content_length : int
The length in the TMD's content record of the content being decrypted.
Returns
-------
@ -60,18 +62,15 @@ def decrypt_content(content_enc, title_key, content_index, content_length):
content_index_bin = struct.pack('>H', content_index)
while len(content_index_bin) < 16:
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.
padded = False
if (len(content_enc) % 128) != 0:
print("needs padding to 16 bytes")
content_enc = pad(content_enc, 128, "pkcs7")
padded = True
# Align content to 64 bytes to ensure that all the data is being decrypted, and so it works with AES encryption.
if (len(content_enc) % 64) != 0:
print("needs padding to 64 bytes")
content_enc = content_enc + (b'\x00' * (64 - (len(content_enc) % 64)))
# 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)
# Decrypt the content using the AES object.
content_dec = aes.decrypt(content_enc)
# Remove padding bytes, if any were added.
if padded:
while len(content_dec) > content_length:
content_dec = content_dec[:-1]
# Trim additional bytes that may have been added so the content is the correct size.
while len(content_dec) > content_length:
content_dec = content_dec[:-1]
return content_dec

2
src/libWiiPy/ticket.py
View File

@ -1,7 +1,7 @@
# "ticket.py" from libWiiPy by NinjaCheetah & Contributors
# https://github.com/NinjaCheetah/libWiiPy
#
# See https://wiibrew.org/wiki/Ticket for details about the TMD format
# See https://wiibrew.org/wiki/Ticket for details about the ticket format
import io
from .crypto import decrypt_title_key

10
src/libWiiPy/types.py
View File

@ -22,8 +22,8 @@ class ContentRecord:
content_hash
The SHA-1 hash of the decrypted content.
"""
content_id: int # Unique ID for the current content
index: int # Index in the list of contents
content_type: int # Type of content, possible values of: 0x0001: Normal, 0x4001: DLC, 0x8001: Shared
content_size: int # Size of the current content
content_hash: bytes # SHA1 hash of the current content
content_id: int # The unique ID of the content.
index: int # The index of this content in the content record.
content_type: int # Type of content, possible values of: 0x0001: Normal, 0x4001: DLC, 0x8001: Shared.
content_size: int # Size of the content when decrypted.
content_hash: bytes # SHA-1 hash of the content when decrypted.