foo.ucsd.edu % cat input
01010101000111
foo.ucsd.edu % crcgen input
11011011
foo.ucsd.edu % cat crcinput
0101010100011111011011
foo.ucsd.edu % crccheck crcinput
Valid CRC
foo.ucsd.edu % cat badcrcinput
1101010100011111011011
foo.ucsd.edu % crccheck badcrcinput
Invalid CRC