After DeCSS, DVD Jon Releases DeDRMS

An anonymous reader writes "Jon Lech Johansen, who reverse engineered FairPlay back in January, and wrote the decryption code that was later used by an anonymous developer to create the playfair utility, has released a similar utility: DeDRMS. It's only 230 lines. T-shirts anyone?"

Comments

Re:Looks like his webserver was written in C#!

[Anonymous Coward]

I was fortunate enough to load the page during the 1 minute that the server stayed up.

Now let's see how long my little mirror stays up!

http://fire.prohosting.com/xonerate/dedrms.txt

Re:Looks like his webserver was written in C#!

[Anonymous Coward]

Stupid junk filter doesn't let me post this. Why oh why? Code after filler...

In the beginning God created the heaven and the earth.
2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
3 And God said, Let there be light: and there was light.
4 And God saw the light, that it was good: and God divided the light from the darkness.
5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
6 And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
8 And God called the firmament Heaven. And the evening and the morning were the second day.
9 And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.
10 And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.
11 And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.
12 And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good.
13 And the evening and the morning were the third day.
14 And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:
15 And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
16 And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
17 And God set them in the firmament of the heaven to give light upon the earth,
18 And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
19 And the evening and the morning were the fourth day.
20 And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven.
21 And God created great whales, and every living creature that moveth, which the waters brought forth abundantly, after their kind, and every winged fowl after his kind: and God saw that it was good.
22 And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let fowl multiply in the earth.
23 And the evening and the morning were the fifth day.
24 And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.
25 And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.
26 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
27 So God created man in his own image, in the image of God created he him; male and female created he them.
28 And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.
29 And God said, Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat.
30 And to every beast of the earth, and

Re:Curious how he wrote it in C#.

[Anonymous Coward]

I was able to access the README before the server went down:

Compiling:

* With MonoDevelop [1]: Open DeDRMS.cmbx and click F8.
* With mcs [2]: mcs -out:DeDRMS.exe *.cs
* With csc [3]: csc /out:DeDRMS.exe *.cs

[1] http://www.monodevelop.org
[2] http://www.go-mono.com
[3] http://msdn.microsoft.com/netframework/technologyi nfo/howtoget/

Usage:

* DeDRMS.exe file.m4p

Notes:

DeDRMS requires that you already have the user key file(s) for
your files. The user key file(s) can be generated by playing
your files with the VideoLAN Client [1][2].

DeDRMS does not remove the UserID, name and email address.
The purpose of DeDRMS is to enable Fair Use, not facilitate
copyright infringement.

[1] http://www.videolan.org/vlc/
[2] http://wiki.videolan.org/tiki-read_article.php?art icleId=5

Re:Curious how he wrote it in C#.

[Sam H]

Using C# makes sense to me. It provides Rijndael and MD5 in System.Security.Cryptography out of the box. These cypher and hash algorithms are at the core of the DRMS encryption scheme. The same code in C would either use obscure libraries or 1000 extra lines of code.

Re:Curious how he wrote it in C#.

[t_pet422]

I don't even have a C# compiler.

Install the .NET Framework (run Windows Update). It will install one at %WINDIR%\Microsoft.NET\Framework\v1.1.4322\csc.exe
You can compile this with csc /out:DrDRMS.exe *.cs

Re:pretty cool...

[TravisWatkins]

No, it's not up to the player to enforce the DRM. When you purchase a song from iTunes you are given the DRM'ed file, an md5 hash of the file, and two keys. Not sure what the other key is for, but one is the encryption key. You put that with the song and you get a DRM free song. Thats exactly what this does. PS - Reverse engineering the iTMS is fun!

What this does

[EvilGrin666]

For those of you that don't know. It removes the protection from a .m4p file (Downloaded with iTunes) . So basically you end up with a Vanilla AAC file.

Or for those of you on a Linux box

[dethl]

1. Get and compile Mono (emerge mono for those of you with Gentoo). 2. In the command line, type: mcs DeDRMS.cs 3. Then type: mono DeDRMS.exe There ya go!

Why C# can outperform C/C++

[ca1v1n]

Remember that research that found that emulating the underlying hardware with a sufficiently intelligent userland dynamic profiler was usually faster than running directly on the underlying hardware? The dynamic profiler can optimize like no compiler will ever be able to do with static analysis. It's a similar principle to what Transmeta does with their x86 emulation. Modern Just-In-Time Compilers use dynamic profiling to accelerate things, and they're getting quite good. It's certainly quite possible to design a C# vector class that's both more memory and processor efficient in most cases than C++. Here's how:

1) Record in the virtual machine/JIT every time a vector gets resized.
2) Based on the pattern of resizing, speculatively allocate for new vectors/resizes as much memory as they'll ever need, or at least as much as they'll need any time soon.
3) When you guess wrong about a speculative allocation, adjust your speculation.

C++ doubles the amount of space allocated for a vector (or queue, or list, or stack, or dequeue, or binary heap, etc) whenever a resize exceeds the amount already allocated, unless you know enough to tell it to do otherwise. This keeps the amortized cost of increasing size by one constant. C++ doesn't benefit from profiling like C# does because there's no virtual machine that can change what binary code is actually sent to the processor. You could hack vector profiling together yourself, but it would be slow. Of course, this doesn't really help C# if you're never resizing your vectors, but that doesn't mean C# can't do better than C, even if C++ will have it beat. If you've ever done much benchmarking of the C++ STL, you know that it's usually faster than otherwise identical code written with arrays, which shouldn't be possible, since the array access code can be done fairly easily in assembly without virtual function table lookups and such, but nonetheless is quite real.

The trick to this whole scheme is doing the speculation quickly and accurately. We may not be to the point yet where JIT code reliably outperforms statically compiled code in less space, but there are an army of extraordinarily intelligent grad students out there writing dissertations on the topic, and I assure you they'll make it happen.