Recently for a mastering class, I had to research this same exact problem. How do you put your isrc and even a upc onto a .wav or other digital file and have it embedded and not be changed by end users to evade drm or copyright protection.
I posted the findings on my blog which is HERE
. Some of the data might be wrong as I did all the research the night before it was due. Please pm me or tell me in the forum if anything said is false or wrong...I will try my best to correct the blog post to mirror those said changes.
In short the only real way to embed data and have it protected from the end user is to use a "watermarking" program (usually expensive but works well). If you have worked with photos at all, you may be aware of photo watermakring and it does much the same thing. But you "supposedly" (the verdict isnt out yet due to no mass production) cannot hear the embedded signal in the audio file.