Crypt::AppleTwoFish -- two Apple iTMS/iTunes key descrambling algorithms

The first algorithm appears to have only cursory resemblance to Bruce Schneier's blowfish and twofish algorithms in that it too has a table-based decoder.

The second algorithm is more standard encryption using S-box type permutations and lookup tables, and might have started out something like Twofish or Blowfish.

    for iTMS usages:

    use Crypt::AppleTwoFish;

    my $scrambled_key = '=sixteen uchars=';

    my $apple_twofish = new Crypt::AppleTwoFish(key => $scrambled_key);

    my $descrambled_key = $apple_twofish->decrypted_for_iTMS;

    my $descrambled_another_way = $apple_twofish->decrypted_for_DRMS;




    ..and for iTunes 7 compatible usages:

    Functions cloned from lower level compiled code which was likely intended
    to be difficult to reconstruct cannot easily be given sensible names. Ada 
    Pro is good, but dull.  We chose to be amused during the tedium by coming 
    up with function names from a vegetable farm. 

    For actual usage, see also:

iTunes::Sid.

new

Call with the key as a scalar argument. When passed (LWP simulating iTunes) over iTMS, encrypted M4P keys for your purchased music are currently 16 unsigned chars in length.

decrypted_for_iTMS

Returns the unscrambled key for use with the Apple Music Store.

decrypted_for_DRMS

Returns the unscrambled key for use with iTunes/iPod DRM.

key

    Get/set initial key.

int_table

    Get/set veggie integer table.

byte_table

    Get/set veggie byte table.

veggie

    Get/set veggie.

hwID

    Get/set hardware ID (MAC address or other machine based data). 6 bytes.

keyID

    Get/set key ID.  4 bytes.

userID

    Get/set user ID.  4 bytes.

plant_veggies

    Key munging, spring season

harvest_veggies

    Key munging, harvest season

   iTMS decrambler adapted from FairKeys 0.5, by Jon Lech Johansen, and from 
   the alterate scramble table found by FutureProof. 

   Veggie Tales algorithm courtesy of Ada and other anonymous pros :-).

Questions, feature requests and bug reports should go to <wherrera@skylightview.com>.

    Copyright (c) 2005, 2008 William Herrera. All rights reserved.  

    Licensing Terms

    a) The terms of Perl itself, plus the following:

    b) UNDER NO CIRCUMSTANCES CAN THIS CODE BE USED FOR CIRCUMVENTION OF ANY 
    TECHNOLOGICAL MEASURE WHICH EFFECTIVELY CONTROLS A PROTECTED MEDIA WORK 
    UNDER THE DCMA (USA, 1998) OR EU COPYRIGHT DIRECTIVE (EUCD, ARTICLE 6, 
    OF 2001), UNDER ANY OPERATING SYSTEM PLATFORM SUPPORTED BY APPLE COMPUTER 
    CORPORATION FOR ITS ITUNES OR IPOD PLAYER SOFTWARE IN ANY APPLE CORPORATION 
    DISTRIBUTED BINARY FORMAT OF ITUNES FOR THE PLATFORM UNDER WHICH THAT MEDIA 
    IS TO BE PLAYED. AS OF 2008, PROHIBITED PLATFORMS INCLUDE THE IPOD, IPHONE, 
    APPLE OS X, AND MICROSOFT WINDOWS, BUT NOT LINUX, BSD, OR SOLARIS.  UNDER NO 
    CIRCUMSTANCES CAN THE AUTHOR(S) OF THIS CODE BE HELD LIABLE FOR ANY 
    INFRINGEMENT INVOLVING THE PROHIBITED PLATFORMS ABOVE.

    c) Use, storage, or distribution of this code implies that you accept that 
    its intended purpose is legal and legitimate under any applicable US or EU 
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