- Clip 1 is the original sound file
- Clip 2 is encoded with AES-ECB and scrambled lower 1 bits
- Clip 3 is has nothing encoded, but scrambled lower 1 bits
If you look at the clips visually with a sound editing program they all appear the same even at extreme zooms:
The audio clips sound the same as well, so how can you tell them apart? As it turns out the original WAV file compresses better than the files with the scrambled lower bits (43% vs. 38%). After you narrow down the data to clips 2 and 3 you could then extract the lower 1 bits from each and perform an analysis on them. The AES encyption method that we used (and are replacing) is block based and leaves a detectable pattern. Once you figure out how big the block of data is you could then turn to traditional means of breaking AES.
From here on we are working on replacing AES ECB with a better AES algorithm in an effort to reduce detectability. We are also investigating ways to reduce the randomness of our random data padding so that the compression ratio is the same as or similar to the original file's ratio.
