commit 99495f22f022415961b2e374f7b9bd9629640432
Author: NWPlayer123 <NWPlayer123@users.noreply.github.com>
Date:   Thu Sep 10 19:55:27 2020 -0600

diff --git a/decrypt_tad.py b/decrypt_tad.py
new file mode 100644
index 0000000..c200c2d
--- /dev/null
+++ b/decrypt_tad.py
@@ -0,0 +1,113 @@
+from io import BytesIO
+from struct import unpack
+from binascii import hexlify, unhexlify
+from Crypto.Cipher import AES #pip install pycryptodome
+import sys
+
+def generate_key(string):
+    key_hex = int(string, 16)
+    key_add = int(b"1" * 32, 16)
+    combine = key_hex + key_add
+    return unhexlify(b"%032X" % combine)
+
+dsi_common_key = generate_key(b"9E0AE40596F6C109D934873DF3631750")
+wii_debug_key = generate_key(b"904F39596012A4189D7ADB21B705EB99")
+
+def align(val): #Tads have 64-byte alignment between sections
+    return val + (64 - (val % 64))
+
+with open(sys.argv[1], "rb") as f:
+    header = unpack(">I2sH6I", f.read(0x20))
+    if header[1] != b"Is": #Installable? same-ish as Wii WADs
+        raise BaseException("Invalid TAD file")
+    if header[0] != 0x20: #header size
+        raise BaseException("unknown header size %d" % header[0])
+    if header[2] != 0: #WAD version according to wiibrew
+        raise BaseException("unknown TAD version %d" % header[2])
+    
+    print("Input Tad file: %s" % sys.argv[1])
+    print("Header: %08X cert %08X ticket %08X tmd %08X content %08X footer" %\
+          (header[3], header[5], header[6], header[7], header[8]))
+    
+    with open("title.cert", "wb") as o:
+        o.write(f.read(header[3]))
+        f.seek(align(f.tell()))
+        
+    ticket = BytesIO(f.read(header[5])) #store to parse a bit
+    f.seek(align(f.tell()))
+    with open("title.tik", "wb") as o:
+        o.write(ticket.read())
+        ticket.seek(0)
+
+    tmd = BytesIO(f.read(header[6])) #store to parse a bit
+    f.seek(align(f.tell()))
+    with open("title.tmd", "wb") as o:
+        o.write(tmd.read())
+        tmd.seek(0)
+
+    tmd.seek(0x18C)
+    title_id = tmd.read(8)
+    tmd.seek(0x1DE)
+    content_count, boot_index = unpack(">2H", tmd.read(4))
+    print("Title ID: %016X %s" % (unpack(">Q", title_id)[0], title_id[4:].decode("UTF-8")))
+    
+    ticket.seek(0x1BF)
+    enc_title_key = ticket.read(0x10)
+    print("Encrypted Title Key: %032X" % (int(hexlify(enc_title_key), 16)))
+    if content_count > 1:
+        raise BaseException("Multiple contents not supported, very easy to add")
+
+    #if you encounter multi-content files, handle tmd table here, and then assume
+    #content is in a row in the content blob in the TAD
+
+    content = BytesIO(f.read(header[7]))
+    f.seek(align(f.tell()))
+    with open("%08X" % boot_index, "wb") as o: #store the encrypted content
+        o.write(content.read())
+        content.seek(0)
+
+    if header[8] != 0: #there is a footer
+        with open("footer.bin", "wb") as o:
+            o.write(f.read(header[8]))
+        f.seek(align(f.tell()))
+
+    title_id += b"\x00" * 8 #pad to 16 bytes for IV
+
+    obj = AES.new(dsi_common_key, AES.MODE_CBC, title_id)
+    dsi_dec_title_key = obj.decrypt(enc_title_key)
+    obj = AES.new(wii_debug_key, AES.MODE_CBC, title_id)
+    wii_dec_title_key = obj.decrypt(enc_title_key)
+
+    #try both keys and check the srl's "reserved" bytes, we decrypt the entire file
+    #because otherwise the CBC blocks get off and the start of the srl gets garbled
+    obj = AES.new(dsi_dec_title_key, AES.MODE_CBC, b"\x00" * 16)
+    decrypted_content = BytesIO(obj.decrypt(content.read()))
+    content.seek(0)
+    decrypted_content.seek(0x15) #reserved bytes
+    if decrypted_content.read(7) == b"\x00" * 7: #this is an srl
+        decrypted_content.seek(0xC)
+        print("DSi Common Key Used")
+        game_code = decrypted_content.read(6).decode("UTF-8") #for export filename
+        print("Game Code: %s" % game_code)
+        decrypted_content.seek(0)
+        print("Output file name: %s.srl" % game_code)
+        with open("%s.srl" % game_code, "wb") as o:
+            o.write(decrypted_content.read())
+        sys.exit(1)
+
+    obj = AES.new(wii_dec_title_key, AES.MODE_CBC, b"\x00" * 16)
+    decrypted_content = BytesIO(obj.decrypt(content.read()))
+    content.seek(0)
+    decrypted_content.seek(0x15) #reserved bytes
+    if decrypted_content.read(7) == b"\x00" * 7: #this is an srl
+        decrypted_content.seek(0xC)
+        print("Wii Debug Key Used")
+        game_code = decrypted_content.read(6).decode("UTF-8") #for export filename
+        print("Game Code: %s" % game_code)
+        decrypted_content.seek(0)
+        print("Output file name: %s.srl" % game_code)
+        with open("%s.srl" % game_code, "wb") as o:
+            o.write(decrypted_content.read())
+        sys.exit(1)
+
+    raise BaseException("Was not able to decrypt the content, oops")