B a c k u p H D - D V D F A Q V 1 . 0 0

[joepic]

To help everyone understand what Backup HD-DVD is I have copied the FAQ here:


B a c k u p H D - D V D F A Q V 1 . 0 0


-Who are you?

Just an ordinary guy, who like cryptography and don't like DRM.

-What is "Backup HDDVD" for?

It can do backup copies of HD DVD movies that YOU OWN! I don't want anyone to do
piracy here! This software is a good way to protect your investment, because I have
notice that this type of media seems very fragile, if it's scratched a little or
dirty, it won't play. It seems less tolerant than DVD format. (Higher density!)

And, if like me you don't have a HDCP video card and monitor, it's a good way for
you to enjoy full HD quality on your HD monitor. When a movie is decrypted, the player
will "accept" to play it on your hardware even you don't have HDCP.


-What "Backup HDDVD" is doing exactly?

This is a java based command line utility that decrypt video files (.evo) from a
HD DVD disk that you own, to your hard drive and you can play them back with a
HD DVD player software.

-What are the system requirements to use "Backup HDDVD"

1 - A Windows based system
2 - A HDDVD disk drive
3 - A HDDVD player software (like PowerDVD)
4 - A HDDVD movie(s)
5 - Java runtime 1.5
6 - The possibility to access the content of the disk with a drive letter under windows.
(you may need UDF 2.5 file system driver for this)
7 - A lot of free hard disk space to backup your movies!


-Was your first HDDVD movie hard to decrypt?

It took me about a week to do. But I have wasted few days
trying to work on too complicated approach. In fact, it is very simple.


-How do you do that?

The program itself has nothing special. It simply implement the AACS
decryption protocol. I have followed the freely available documents about AACS
Have a look at: www.aacsla.com
The trick, is to find what they call the "Title keys" or "volume unique key".
So I figure out how to extract them.

-What are title keys?

The title keys are used to decrypt media files. You can have up to 64 title keys
on a disk. These keys can be use in different ways.

1- Only one title key decrypt all the media files on the disk.
2- Each media file have a different title key.
3- Each media file may use several title keys.

-Where are title keys?

The title keys are encrypted on the disk.

-What is the volume key?

The volume key is the key used to decrypt the title keys. So the volume key is all you need to decrypt a movie.

-Where is the volume key?

The volume key is the result of several complex decryption process. Read AACS doc for more details.

-Should I use volume key or titles keys?

The volume key is what you want. If for some reasons, your extraction technique don't allow you to recover
the volume key, you can still use BackupHDDVD with title keys.


-How do you extract title/volume keys?

I won't explain it in detail. Read the AACS doc first. You will understand.
The title keys are located on the disk in encrypted form, but for a
content to be played, it has to be decrypted! So where is the
decrypted version of the title/volume keys? Think about it...

-What kind of crypto algorithms are involved?
Standards algorithms:
ECC-160
AES-128

-What is the KEYDB.cfg file?

This is the key Database file. It holds the decryption keys for the movies.


-What is the format of this file?

Field 1: SHA1 Hash of the VTKF000.AACS file on your HDDVD disk.

Next fields are pipe "|" delimited.

Field 2: Movie Title
Field 3: Key type (V or T for Volume or Title key)
Field 4: File creation date
This field is informational only. It's ignored by the program. It should be the creation date of the media file on the
disk.

Field 5:A variable number of Title key, pipe delimited or one volume key

In the case of a title keys, you have a key number followed by the key value like:

12-08A3DC61910280F2...

Key values are 128 bits long, so 16 bytes, or 32 hexadecimal characters long.


-The KEYDB.cfg file provided with your program is empty or incomplete, what can I do?

Well, you are on your own.


-What do you think of the technical aspects of AACS?

The design is not that bad, but it's too easy to have an insecure player
implementation somewhere. And just one bad implementation is all it needs
to get the keys! There will always be insecure implementations
of a player somewhere! And the "Revocation system" is totaly useless if you use
the volume key directly.


-Is there any known problems with the decryption?

Yes. I call this problem the "Nav chain" bug. I realize that I have a lot of
frame skipping at playback after the decryption, so I hunted down the problem.
To avoid the frame skipping, I patch the video file.
This fix allows smooth playback of the movie, but there are some side effects.


-What are the side effects of the "Nav chain" bug fix?

You cannot do fast forward, or backward using the round dial, but you can still
use the progress bar to navigate through the film. So it's not that bad...

For some reason, the sub-titles don't seems to work anymore.
It may be a side effect of the nav chain bug. But may be not...


-Why the "Nav chain" bug is called the "Nav chain" bug?

Well, it has something to do with the chaining of navigation pack.
Look at some doc about standard DVD VOB file, you will see.
If someone wants to help me with that bug, please do!


-Are you going to support Blu-Ray?

I don't own a Blu-Ray drive!


-Do you plan to do a user interface version?

No, other people will do. You have the source code, so enjoy it!


-Do you plan to do a Linux version?

See the previous answer.
I don't use any windows specific API and this is a java application!
A port to Linux will be easy.


-Can you send me some decryption keys? PLEASE!

No.


-I have a question for you, can I send you an e-mail?

If you have something like, a technical problem using the software, look in the forums
talking about Backup HDDVD first. There will be a lot of information and everyone will help
each other out. If there is a major flaw in the program, I will post another version,
but honestly I really want people to bring Backup HDDVD to a higher level without me!

[oldfart13]

Nice review of what it takes to back up a HD-DVD but many of us are awaiting the software from places like AnyDVD that will allow us to do the same thing basically as a "1-Click" solution. That has already been announced as being in Alpha so I would assume a Beta will be available shortly.