Hi Ali8. Actel/Microsemi make a big deal of DPA and it would be worth you reading some of their white papers on the subject. It appears at first sight to me, however that the DPA "hit" occurs when a match is found, so hiding the encryption key amongst a flood of other data probably isn't going to help a great deal if the IP theft was considered worthwhile.
Your suggestion has some merit, but I suspect it is a little simplistic in approach, perhaps by collating the bit stream fron multiple sources and using multiple independent task handlers to decrypt a part of it followed by some form of reassembly. I don't know, its just a guess, but search DPA on the Actel website and read what they have to say.