http://rapidshare.de/files/13062449/10486171404.rar.html this format of audio is exclusive of www.ATR.com.mx single can reproduced with its system has the same quality that mp3 but but is reduced
probably it is so using this program mp3stego of Encryptation and zlib as they used in its installer http://www.petitcolas.net/fabien/steganography/mp3stego/index.html
MP3Guard MP3 Music Protection MP3Guard Player This is the software that encrypts your MP3 files so that they can only be played by the specifed MP3 Player. This program allows you to create a mp3 playlist and then encrypt the playlist with different parameters to enable various marketing uses. http://www.zappersoftware.com/mp3guard.html
I am 100% sure you are using PKI encryption algorithms http://rapidshare.com/files/108124386/188851154328.MP3