The fastCDC paper says they used random values. "It employs an array of 256 random 64-bit integers to map the values of the byte contents in the sliding window

The fastCDC paper says they used random values. "It employs an array of 256 random 64-bit integers to map the values of the byte contents in the sliding window" I presume using something else would skew the distribution of selected chunks. I don't know if that would help or hinder. In my very limited experience, a picture of Rick Astley as the constants gave a similar distribution™ of chunks over a mixture of documentation files and Linux ISOs.