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Obviously this section is not present in TWL CIA files.
Obviously this section is not present in TWL CIA files.
+
+
+== Title Key Encryption ==
+
+The unencrypted Title Key is used to encrypt the data in a CIA. The encrypted Title Key of a CIA can be found at offset 0x1BF in a CIA's Ticket.
+Each Title Key is encrypted with AES-CBC.
+
+To encrypt an unencrypted title key, you need:
+
+* Common key (as byte array)
+* Title ID (as ulong)
+* (and of course the unencrypted title key you want to encrypt) (as byte array)
+
+The title ID encryption process starts by converting the ulong (Title ID) into a byte array using by retrieving the bytes of the Title ID using BitConverter.GetBytes().
+If the converted bytes (title ID) are in Little Endian, reverse those bytes. (in C# it would be Array.Reverse(byte_array_from_bitconverter))
+This process makes the Title Key encryption IV.
+
+Next, after you've gotten your Title Key's IV, you can start your cryptography transformation. Using AESManaged, where:
+
+Key = Common Key
+
+IV = the byte array found in the conversion process above
+
+Mode = CipherMode.CBC
+
+Create the encryptor (AesManaged.CreateEncryptor(key, iv)) where the key and IV are both the same as above.
+
+Then, create a CryptoStream and a MemoryStream. The Crypto stream should start with the arguments (memorystream, aes_transform_from_above, CryptoStreamMode.Write).
+
+Write to the CryptoStream where buffer=unencrypted_titlekey, offset=0, and count=the length of the unencrypted title key.
+
+Use FlushFinalBlock() on the CryptoStream.
+
+Finally, then, the encrypted title key will be available from your memory
+stream. (to output the calculated encrypted title key as a byte array, you can use memorystream.ToArray(), for example)
+
+Example function: (C#)
+
+<pre>
+ public static byte[] EncryptMyTitleKey(byte[] commonKey, byte[] titleKey, ulong titleId)
+ {
+ byte[] titleidasbytes = new byte[0x10];
+ for (int i = 0; i < 0x10; i++)
+ {
+ titleidasbytes[i] = 0;
+ }
+ byte[] bitBytes = BitConverter.GetBytes(titleId);
+ if (BitConverter.IsLittleEndian)
+ {
+ Array.Reverse(bitBytes);
+ }
+ bitBytes.CopyTo(titleidasbytes, 0);
+ ICryptoTransform transform = new AesManaged { Key = commonKey, IV = titleidasbytes, Mode = CipherMode.CBC }.CreateEncryptor(commonKey, titleidasbytes);
+ MemoryStream memstream = new MemoryStream();
+ CryptoStream cryptostream = new CryptoStream(memstream, transform, CryptoStreamMode.Write);
+ cryptostream.Write(titleKey, 0, titleKey.Length);
+ cryptostream.FlushFinalBlock();
+ return memstream.ToArray();
+ }
+</pre>