Added Title Key generation code

modules/tkey.py

@@ -0,0 +1,53 @@
+# "tkey-gen.py", licensed under the MIT license
+# Copyright 2024 NinjaCheetah
+
+import binascii
+import hashlib
+import libWiiPy
+from libWiiPy.types import _ContentRecord
+
+
+def _secret(start, length):
+    ret = b''
+    add = start + length
+    for _ in range(length):
+        unsigned_start = start & 0xFF  # Compensates for how Python handles negative values vs PHP.
+        ret += bytes.fromhex(f"{unsigned_start:02x}"[-2:])
+        nxt = start + add
+        add = start
+        start = nxt
+    return ret
+
+
+def _mungetid(tid):
+    # Remove leading zeroes from the TID.
+    while tid.startswith("00"):
+        tid = tid[2:]
+    if tid == "":
+        tid = "00"
+    # In PHP, the last character just gets dropped if you make a hex string from an odd-length input, so this
+    # replicates that functionality.
+    if len(tid) % 2 != 0:
+        tid = tid[:-1]
+    return bytes.fromhex(tid)
+
+
+def _derive_key(tid, passwd):
+    key_secret = _secret(-3, 10)
+    salt = hashlib.md5(key_secret + _mungetid(tid)).digest()
+    # Had to reduce the length here from 32 to 16 when converting to get the same length keys.
+    return hashlib.pbkdf2_hmac("sha1", passwd.encode(), salt, 20, 16).hex()
+
+
+def find_tkey(tid: str, banner_enc: bytes, content_record: _ContentRecord) -> bytes:
+    # Find a working Title Key by generating a key with a password, then decrypting content 0 and comparing it to the
+    # expected hash. If the hash matches, then we generated the correct key.
+    passwds = ["nintendo", "mypass"]
+    for passwd in passwds:
+        key = binascii.unhexlify(_derive_key(tid, passwd).encode())
+        banner_dec = libWiiPy.title.decrypt_content(banner_enc, key, content_record.index, content_record.content_size)
+        banner_dec_hash = hashlib.sha1(banner_dec).hexdigest()
+        content_record_hash = content_record.content_hash.decode()
+        if banner_dec_hash == content_record_hash:
+            return key
+    raise Exception("Valid Title Key could not be generated")